Implementing SNMP SendTrap using Indy components - snmp

I need to report errors from my application on C++Builder via SNMP.
I started implementing SNMP SendTrap using Indy components.
void __fastcall TMainForm::btSendTrapClick(TObject *Sender)
{
UnicodeString myEnterprise = "1.5.5.5.5.5.5.5";
UnicodeString eventType = "1.5.5.5.5.5.5.5.1";
UnicodeString eventDistance = "1.5.5.5.5.5.5.5.2";
TIdSNMP * idSnmp = 0;
TSNMPInfo * infoSnmp = 0;
idSnmp = new TIdSNMP(NULL);
infoSnmp = new TSNMPInfo(idSnmp);
idSnmp->Host = edHost->Text;
idSnmp->Community = "public";
infoSnmp->Host = edHost->Text;
infoSnmp->Community = "public";
infoSnmp->Enterprise = myEnterprise;
infoSnmp->GenTrap = 6; // I've met such values
infoSnmp->SpecTrap = 1; // somewhere in inet
infoSnmp->MIBAdd(eventType,"ftCritical");
infoSnmp->MIBAdd(eventDistance,"2.357");
idSnmp->SendTrap();
delete idSnmp;
}
But when I run application there is no udp activity in my system. When I run something like this
idSnmp->QuickSend(sysDescr, "public", edHost->Text, val);
wireshark shows 192.168.100.21 192.168.100.19 SNMP 82 get-request 1.3.6.1.2.1.1.3.0
but when idSnmp->SendTrap() wireshark sees nothing (filter for wireshark is UDP portrange 161-162 in both cases)
I'll be glad to see some remarks about my code or maybe working example of SendTrap :)


You are not populating TIdSNMP::Trap with any values. That is why TIdSNMP::SendTrap() is not sending anything. There is nothing for it to send.
Try this instead:
void __fastcall TMainForm::btSendTrapClick(TObject *Sender)
{
String myEnterprise = _D("1.5.5.5.5.5.5.5");
String eventType = myEnterprise + _D(".1");
String eventDistance = myEnterprise + _D(".2");
TIdSNMP *idSnmp = new TIdSNMP(NULL);
idSnmp->Trap->Host = edHost->Text;
idSnmp->Trap->Community = _D("public");
idSnmp->Trap->Enterprise = myEnterprise;
idSnmp->Trap->GenTrap = 6; // I've met such values
idSnmp->Trap->SpecTrap = 1; // somewhere in inet
idSnmp->Trap->MIBAdd(eventType, _D("ftCritical"));
idSnmp->Trap->MIBAdd(eventDistance, _D("2.357"));
idSnmp->SendTrap();
delete idSnmp;
}
Alternatively, you can use TIdSNMP::QuickSendTrap() instead:
void __fastcall TMainForm::btSendTrapClick(TObject *Sender)
{
String myEnterprise = _D("1.5.5.5.5.5.5.5");
String eventType = myEnterprise + _D(".1");
String eventDistance = myEnterprise + _D(".2");
TStringList *names = new TStringList;
names->Add(eventType);
names->Add(eventDistance);
TStringList *values = new TStringList;
values->AddObject(_D("ftCritical"), (TObject*)ASN1_OCTSTR);
values->AddObject(_D("2.357"), (TObject*)ASN1_OCTSTR);
TIdSNMP *idSnmp = new TIdSNMP(NULL);
idSnmp->QuickSendTrap(edHost->Text, myEnterprise, _D("public"), 162, 6, 1, names, values);
delete idSnmp;
delete names;
delete values;
}
Or, if you are compiling for mobile:
void __fastcall TMainForm::btSendTrapClick(TObject *Sender)
{
String myEnterprise = _D("1.5.5.5.5.5.5.5");
String eventType = myEnterprise + _D(".1");
String eventDistance = myEnterprise + _D(".2");
TIdMIBValueList *mibs = new TIdMIBValueList;
mibs->Add(TIdMIBValue(eventType, _D("ftCritical"), ASN1_OCTSTR));
mibs->Add(TIdMIBValue(eventDistance, _D("2.357"), ASN1_OCTSTR));
TIdSNMP *idSnmp = new TIdSNMP(NULL);
idSnmp->QuickSendTrap(edHost->Text, myEnterprise, _D("public"), 162, 6, 1, mibs);
delete idSnmp;
delete mibs;
}

Related

Response status code does not indicate success: '400' ('Bad request')

i want to POST data to API in my android xamarin app using refit i've tested the API at Postman and it's working fine but at android app i'm getting exception Bad request.
Here is my android code i added the interface and the model i don't know what is the problem .
public interface RequestAPI
{
[Post("/request")]
Task<create_request> submit([Body] create_request request);
}
requestAPI= RestService.For<RequestAPI>("http://courier-magconsulting.azurewebsites.net/api");
button.Click += async delegate
{
try
{
create_request request = new create_request();
request.PickUpPhone = "7664554";
request.DownPayment = 89;
request.DeliveryFees = 56.8;
request.Note = "i need a help!";
request.RequestID = 88; // replace the value yourself
request.DekiveryLocationLatitude = 2323;
request.DeliveryLocationLongitude = 232;
request.PickUpLocationLatitude = 898;
request.PickUpLocationLongitude = 1123;
BroadcastType type = new BroadcastType();
type.Name = "All";
type.ID = 60; // replace the value yourself
request.BroadcastType = type;
Cargosize size = new Cargosize();
size.Name = "Small";
size.ID = 1; // replace the value yourself
request.Cargosize = size;
Cargoweight weight = new Cargoweight();
weight.Name = "Large";
weight.ID = 2; // replace the value yourself
request.CargoWeight = weight;
Sender sender_ = new Sender();
sender_.Name = "Ahmad";
sender_.SenderID = 1; // replace the value yourself
sender_.Phone = "8788";
sender_.SocialID = "8787";
sender_.RatingAvg = 5;
SenderStatus status = new SenderStatus();
status.ID = 1;
status.Name = "Active";
sender_.Senderstatus = status;
request.Sender = sender_;
create_request result = await requestAPI.submit(request);
Toast.MakeText(this, "Request created", ToastLength.Long).Show();
}
catch(Exception ex)
{
Toast.MakeText(this, ex.Message, ToastLength.Long).Show();
}
};

Connecting xamarin to woocommerce api

I'm trying to create my first app that will connect to a woocommerce api.
Has anyone any experience in this or can point me in the direction as to how to create a connection to pull in the product list?
Thanks

Since WooCommerce has a REST API, it should be fairly simple to connect using a plain HTTP request, or a library like RestSharp.
There is also a C# client for WooCommerce - I don't know if it plays well with Xamarin, you might need to modify it a bit to get it to build.
var api = new WoocommerceApiClient(StoreUrl, ConsumerKey, ConsumerSecret);
var result = await api.Products.Get();

It's an old post but I had faced a similar issue. I had tries WoocommerceSharp with Xamarin Studio 6.1.1 (mac version); I opened the .sln file, added the missing reference to system.net.http and it worked perfectly.
If you want make it work in PCL you have to use PCLCrypto in WoocommerceApiUrlGenerator.cs , here the updated version:
namespace SharpCommerce.Web
{
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using PCLCrypto;
internal class WoocommerceApiUrlGenerator
{
private const string SignatureMethod = "HMAC-SHA1";
private const string ApiV3RootEndpoint = "wc-api/v3/";
private readonly string baseURI;
private readonly string consumerKey;
private readonly string consumerSecret;
internal WoocommerceApiUrlGenerator(string storeUrl, string consumerKey, string consumerSecret)
{
if (
string.IsNullOrEmpty(consumerKey) ||
string.IsNullOrEmpty(consumerSecret) ||
string.IsNullOrEmpty(storeUrl))
{
throw new ArgumentException("ConsumerKey, consumerSecret and storeUrl are required");
}
this.consumerKey = consumerKey;
this.consumerSecret = consumerSecret;
// Need 'http://www.example.com' to be 'http://www.example.com/wc-api/v3/'
this.baseURI = String.Format("{0}/{1}", storeUrl.TrimEnd('/'), ApiV3RootEndpoint);
}
internal string GenerateRequestUrl(HttpMethod httpMethod, string apiEndpoint, Dictionary<string, string> parameters = null)
{
parameters = parameters ?? new Dictionary<string, string>();
parameters["oauth_consumer_key"] = this.consumerKey;
// oauth_timestamp = number of seconds since 1/1/1970 00:00:00 GMT
// must be a positive integer
// must be greater than timestamp of previous requests
parameters["oauth_timestamp"] =
Math.Round(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1, 0, 0, 0)).TotalSeconds).ToString(CultureInfo.InvariantCulture);
// oauth_nonce = a unique random string for the timestamp.
// defends against replay attacks
// service provide will know that this request has never been made before.
// Just going to hash the time stamp.
//parameters["oauth_nonce"] = GenerateNonce(parameters["oauth_timestamp"]);
// Create random 32 char alphnumeric to avoid reused nonces
parameters["oauth_nonce"] = GenerateNonce();
// Declare the hashing method your using
parameters["oauth_signature_method"] = SignatureMethod;
//parameters["oauth_version"] = "1.0";
parameters["oauth_signature"] = UpperCaseUrlEncode(this.GenerateSignature(httpMethod, apiEndpoint, parameters));
var sb = new StringBuilder();
foreach (var pair in parameters)
{
sb.AppendFormat("&{0}={1}", SafeUpperCaseUrlEncode(pair.Key), SafeUpperCaseUrlEncode(pair.Value));
}
// Substring removes first '&'
var queryString = sb.ToString().Substring(1);
var url = this.baseURI + apiEndpoint + "?" + queryString;
return url;
}
private string GenerateSignature(HttpMethod httpMethod, string apiEndpoint, Dictionary<string, string> parameters)
{
// 1) Set the HTTP method for the request.
// set through 'method'
//2) Set your base request URI – this is the full request URI without query string parameters – and URL encode according to RFC 3986:
// need 'http://www.example.com/wc-api/v3/orders'
// to become: 'http%3A%2F%2Fwww.example.com%2Fwc-api%2Fv1%2Forders'
var encodedBaseRequestURI = SafeUpperCaseUrlEncode(this.baseURI + apiEndpoint);
// 3) Collect and normalize your query string parameters
// percent(%) characters should be double-encoded (e.g. % becomes %25.
var normalizedParameters = NormalizeParameters(parameters);
// 4) Sort the parameters in byte-order
var orderedNormalizedParameters = normalizedParameters.OrderBy(x => x.Key).ToList();
// 5) Join each parameter with an encoded equals sign (%3D):
//var joinedOrderedNormalizedParameters = orderedNormalizedParameters.ConvertAll(x => x.Key + "%3D" + x.Value);
var joinedOrderedNormalizedParameters = new List<string>();
foreach (var x in orderedNormalizedParameters)
{
joinedOrderedNormalizedParameters.Add(x.Key + "%3D" + x.Value);
}
// 6) Join each parameter key/value pair with an encoded ampersand (%26):
var joinedParameterPairs = String.Join("%26", joinedOrderedNormalizedParameters);
// 7) Form the string to sign by joining the HTTP method, encoded base request URI, and encoded parameter string with an unencoded ampersand symbol (&):
var stringToSign = string.Format("{0}&{1}&{2}", httpMethod.ToString().ToUpper(), encodedBaseRequestURI, joinedParameterPairs);
// 8) Generate the signature using the string to key and your consumer secret key
var preparedStringToSign = Encoding.UTF8.GetBytes(stringToSign);
var secret = this.consumerSecret + "&";
var preparedConsumerKey = Encoding.UTF8.GetBytes(secret);
var signatureHash = Sha1(preparedConsumerKey, preparedStringToSign);
var signatureString = Convert.ToBase64String(signatureHash);
return signatureString;
}
private static byte[] Sha1(byte[] key, byte[] message)
{
var mac = WinRTCrypto.MacAlgorithmProvider.OpenAlgorithm(MacAlgorithm.HmacSha1);
//var keyMaterial = WinRTCrypto.CryptographicBuffer.ConvertStringToBinary(key, Encoding.UTF8);
var cryptoKey = mac.CreateKey(key);
var hash = WinRTCrypto.CryptographicEngine.Sign(cryptoKey, message);
return hash;
//return WinRTCrypto.CryptographicBuffer.CreateFromByteArraymessage);
}
private static Dictionary<string, string> NormalizeParameters(Dictionary<string, string> parameters)
{
var result = new Dictionary<string, string>();
foreach (var pair in parameters)
{
var upperCaseUrlEncodedKey = SafeUpperCaseUrlEncode(pair.Key);
var normalizedKey = upperCaseUrlEncodedKey.Replace("%", "%25");
var upperCaseUrlEncodedValue = SafeUpperCaseUrlEncode(pair.Value);
var normalizedValue = upperCaseUrlEncodedValue.Replace("%", "%25");
result.Add(normalizedKey, normalizedValue);
}
return result;
}
private static string SafeUpperCaseUrlEncode(string stringToEncode)
{
return UpperCaseUrlEncode(System.Net.WebUtility.UrlDecode(stringToEncode));
}
private static string UpperCaseUrlEncode(string stringToEncode)
{
var basicUrlEncodedString = System.Net.WebUtility.UrlEncode(stringToEncode);
if (String.IsNullOrEmpty(basicUrlEncodedString)) return String.Empty;
var upperCaseUrlEncodedString = Regex.Replace(
basicUrlEncodedString,
"(%[0-9a-f][0-9a-f])",
c => c.Value.ToUpper());
return upperCaseUrlEncodedString;
}
private static string GenerateNonce()
{
const string ValidChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
var random = new Random();
var nonceString = new StringBuilder();
for (var i = 0; i < 32; i++)
{
nonceString.Append(ValidChars[random.Next(0, ValidChars.Length - 1)]);
}
return nonceString.ToString();
}
}
}
and in WoocommerceApiDriver.cs you will have to replace
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
return await client.GetStringAsync(url);
}
by
using (var client = new HttpClient()) // must use to avoid Android freezes after repeated calls
{
Task<HttpResponseMessage> r = client.GetAsync(url);
HttpResponseMessage m = r.Result;
return await m.Content.ReadAsStringAsync();
}
Et voila ! ca marche ;)

Best way to handle awt.Image buffering in JavaFX

I have a class that takes a String parameter and performs a google search, then it gets the ten images and puts them in an array, that is then handled by another method in the same class. Using Javafx.scene.image would probably allow me to implement the buffering progress easily, but there is a bug with JavaFX Image, that misinterprets the color encoding of normal Images, and saves a weird looking image to the hard drive, so I just decided to use awt.Image.
This is the image search class:
public class GoogleCustomSearch {
static String key = //custom google id;
static String cx = // also a custom google id;
static String searchType = "image";
static java.awt.Image[] publicImageArray;
public static java.awt.Image[] Search(String searchParameter,int start) throws IOException, URISyntaxException{
String formatedText = URLEncoder.encode(searchParameter,"UTF-8");
URL url = new URL("https://www.googleapis.com/customsearch/v1?" + "key=" +key + "&cx=" +cx + "&q=" +formatedText + "&searchType=" +searchType +"&imgSize=medium" + "&start=" + start + "&num=10");
System.out.println(url);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
BufferedReader br = new BufferedReader(new InputStreamReader( ( conn.getInputStream() ) ) );
GResults results = new Gson().fromJson(br, GResults.class);
java.awt.Image [] imageArray = new java.awt.Image[10];
//JProgressBar prb = new JProgressBar();
//MediaTracker loadTracker = new MediaTracker(prb);
for(int i = 0; i<10; i++){
try {
imageArray[i] = ImageIO.read(new URL(results.getLink(i)));
}catch (java.io.IOException e){
imageArray[i] = ImageIO.read(new File("C:\\Users\\FILIP.D\\IdeaProjects\\Manual_Artwork\\src\\MAT - NoImage.jpg"));
}
}
conn.disconnect();
return imageArray;
}
public static BufferedImage getImage(String searchPar, int index, boolean newSearch) throws IOException, URISyntaxException {
int adaptedIndex;
int start;
BufferedImage bimage;
if(index<10){
adaptedIndex = index;
start = 1;
}else if (index<20){
start = 11;
adaptedIndex = index % 10;
if(index == 10){
publicImageArray = new java.awt.Image[10];
publicImageArray = Search(searchPar,start);
}
}else if(index < 30){
start = 21;
adaptedIndex = index % 10;
if (index == 20) {
publicImageArray = new java.awt.Image[10];
publicImageArray = Search(searchPar,start);
}
}else{
adaptedIndex = index % 10;
start = 21; //ovo ce posle 30 da ga vrti u loop prvih 10
}
if(newSearch){
publicImageArray = new java.awt.Image[10];
publicImageArray = Search(searchPar,start);
return bimage = (BufferedImage) publicImageArray[adaptedIndex];
}else{
return bimage = (BufferedImage) publicImageArray[adaptedIndex];
}
}
public static RenderedImage getLiveImage (int index){
return (RenderedImage) publicImageArray[index % 10];
}
}
And this is the snippet of the main GUI class that just handles opening the new image in the array
private void nextImageResult() throws IOException, URISyntaxException {
if(imgNr == -1){
imgNr++;
changeImage(SwingFXUtils.toFXImage(GoogleCustomSearch.getImage(oppenedTrack.getArtistName() + "+" + oppenedTrack.getTrackName(),imgNr,true),null));
}else{
imgNr++;
changeImage(SwingFXUtils.toFXImage(GoogleCustomSearch.getImage(oppenedTrack.getArtistName() + "+" + oppenedTrack.getTrackName(),imgNr,false),null));
}
}
To summarise, I need a proper way to show a progress bar in the place of the image before it loads, and it needs not to hang the UI, for which I can use Task. I can optimise the loading of the array with MediaTracker, so it can prioritize loading the first few images first.

SHA1 with salt on windows phone 7

I have some some time now reshearchd how to encode a password to SHA1 with a salt.
The is the code i used on my web application part, but it will not work on a phone environment.
public class Password
{
private string _password;
private int _salt;
public Password(string strPassword, int nSalt)
{
_password = strPassword;
_salt = nSalt;
}
public string ComputeSaltedHash()
{
// Create Byte array of password string
ASCIIEncoding encoder = new ASCIIEncoding();
Byte[] _secretBytes = encoder.GetBytes(_password);
// Create a new salt
Byte[] _saltBytes = new Byte[4];
_saltBytes[0] = (byte)(_salt >> 24);
_saltBytes[1] = (byte)(_salt >> 16);
_saltBytes[2] = (byte)(_salt >> 8);
_saltBytes[3] = (byte)(_salt);
// append the two arrays
Byte[] toHash = new Byte[_secretBytes.Length + _saltBytes.Length];
Array.Copy(_secretBytes, 0, toHash, 0, _secretBytes.Length);
Array.Copy(_saltBytes, 0, toHash, _secretBytes.Length, _saltBytes.Length);
SHA1 sha1 = SHA1.Create();
Byte[] computedHash = sha1.ComputeHash(toHash);
return encoder.GetString(computedHash);
}
public static int CreateRandomSalt()
{
Byte[] _saltBytes = new Byte[4];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(_saltBytes);
return ((((int)_saltBytes[0]) << 24) + (((int)_saltBytes[1]) << 16) +
(((int)_saltBytes[2]) << 8) + ((int)_saltBytes[3]));
}
public static string CreateRandomPassword(int PasswordLength)
{
String _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ23456789!\"#¤%&/()=?$+-_.,;'*";
Byte[] randomBytes = new Byte[PasswordLength];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(randomBytes);
char[] chars = new char[PasswordLength];
int allowedCharCount = _allowedChars.Length;
for (int i = 0; i < PasswordLength; i++)
{
chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount];
}
return new string(chars);
}
}

Silverlight and Windows Phone 7 do not have an ASCIIEncoding. I suggest you use the UTF8Encoding instead. If you are certain that your passwords are always within the ASCII range then this encoding will work the same as the ASCIIEncoding would of had it been present.
If on the other hand you cannot guarantee that passwords are always within the ASCII range then you would need to make sure both ends hash using the UTF8Encoding to ensure generated hashs are the same.

What is the best Java email address validation method? [closed]

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
We don’t allow questions seeking recommendations for books, tools, software libraries, and more. You can edit the question so it can be answered with facts and citations.
Closed 5 years ago.
Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
What are the good email address validation libraries for Java? Are there any alternatives to commons validator?

Using the official java email package is the easiest:
public static boolean isValidEmailAddress(String email) {
boolean result = true;
try {
InternetAddress emailAddr = new InternetAddress(email);
emailAddr.validate();
} catch (AddressException ex) {
result = false;
}
return result;
}

Apache Commons is generally known as a solid project. Keep in mind, though, you'll still have to send a verification email to the address if you want to ensure it's a real email, and that the owner wants it used on your site.
EDIT: There was a bug where it was too restrictive on domain, causing it to not accept valid emails from new TLDs.
This bug was resolved on 03/Jan/15 02:48 in commons-validator version 1.4.1

Apache Commons validator can be used as mentioned in the other answers.
pom.xml:
<dependency>
<groupId>commons-validator</groupId>
<artifactId>commons-validator</artifactId>
<version>1.4.1</version>
</dependency>
build.gradle:
compile 'commons-validator:commons-validator:1.4.1'
The import:
import org.apache.commons.validator.routines.EmailValidator;
The code:
String email = "myName#example.com";
boolean valid = EmailValidator.getInstance().isValid(email);
and to allow local addresses
boolean allowLocal = true;
boolean valid = EmailValidator.getInstance(allowLocal).isValid(email);

Late answer, but I think it is simple and worthy:
public boolean isValidEmailAddress(String email) {
String ePattern = "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+#((\\[[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\])|(([a-zA-Z\\-0-9]+\\.)+[a-zA-Z]{2,}))$";
java.util.regex.Pattern p = java.util.regex.Pattern.compile(ePattern);
java.util.regex.Matcher m = p.matcher(email);
return m.matches();
}
Test Cases:
For production purpose, Domain Name validations should be performed network-wise.

If you are trying to do a form validation received from the client, or just a bean validation - keep it simple.
It's better to do a loose email validation rather than to do a strict one and reject some people, (e.g. when they are trying to register for your web service).
With almost anything allowed in the username part of the email and so many new domains being added literally every month (e.g. .company, .entreprise, .estate), it's safer not to be restrictive:
Pattern pattern = Pattern.compile("^.+#.+\\..+$");
Matcher matcher = pattern.matcher(email);

Late to the question, here, but: I maintain a class at this address: http://lacinato.com/cm/software/emailrelated/emailaddress
It is based on Les Hazlewood's class, but has numerous improvements and fixes a few bugs. Apache license.
I believe it is the most capable email parser in Java, and I have yet to see one more capable in any language, though there may be one out there. It's not a lexer-style parser, but uses some complicated java regex, and thus is not as efficient as it could be, but my company has parsed well over 10 billion real-world addresses with it: it's certainly usable in a high-performance situation. Maybe once a year it'll hit an address that causes a regex stack overflow (appropriately), but these are spam addresses which are hundreds or thousands of characters long with many many quotes and parenthesis and the like.
RFC 2822 and the related specs are really quite permissive in terms of email addresses, so a class like this is overkill for most uses. For example, the following is a legitimate address, according to spec, spaces and all:
"<bob \" (here) " < (hi there) "bob(the man)smith" (hi) # (there) example.com (hello) > (again)
No mail server would allow that, but this class can parse it (and rewrite it to a usable form).
We found the existing Java email parser options to be insufficiently durable (meaning, all of them could not parse some valid addresses), so we created this class.
The code is well-documented and has a lot of easy-to-change options to allow or disallow certain email forms. It also provides a lot of methods to access certain parts of the address (left-hand side, right-hand side, personal names, comments, etc), to parse/validate mailbox-list headers, to parse/validate the return-path (which is unique among the headers), and so forth.
The code as written has a javamail dependency, but it's easy to remove if you don't want the minor functionality it provides.

I'm just wondering why nobody came up with #Email from Hibernate Validator's additional constraints. The validator itself is EmailValidator.

Les Hazlewood has written a very thorough RFC 2822 compliant email validator class using Java regular expressions. You can find it at http://www.leshazlewood.com/?p=23. However, its thoroughness (or the Java RE implementation) leads to inefficiency - read the comments about parsing times for long addresses.

I ported some of the code in Zend_Validator_Email:
#FacesValidator("emailValidator")
public class EmailAddressValidator implements Validator {
private String localPart;
private String hostName;
private boolean domain = true;
Locale locale;
ResourceBundle bundle;
private List<FacesMessage> messages = new ArrayList<FacesMessage>();
private HostnameValidator hostnameValidator;
#Override
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
setOptions(component);
String email = (String) value;
boolean result = true;
Pattern pattern = Pattern.compile("^(.+)#([^#]+[^.])$");
Matcher matcher = pattern.matcher(email);
locale = context.getViewRoot().getLocale();
bundle = ResourceBundle.getBundle("com.myapp.resources.validationMessages", locale);
boolean length = true;
boolean local = true;
if (matcher.find()) {
localPart = matcher.group(1);
hostName = matcher.group(2);
if (localPart.length() > 64 || hostName.length() > 255) {
length = false;
addMessage("enterValidEmail", "email.AddressLengthExceeded");
}
if (domain == true) {
hostnameValidator = new HostnameValidator();
hostnameValidator.validate(context, component, hostName);
}
local = validateLocalPart();
if (local && length) {
result = true;
} else {
result = false;
}
} else {
result = false;
addMessage("enterValidEmail", "invalidEmailAddress");
}
if (result == false) {
throw new ValidatorException(messages);
}
}
private boolean validateLocalPart() {
// First try to match the local part on the common dot-atom format
boolean result = false;
// Dot-atom characters are: 1*atext *("." 1*atext)
// atext: ALPHA / DIGIT / and "!", "#", "$", "%", "&", "'", "*",
// "+", "-", "/", "=", "?", "^", "_", "`", "{", "|", "}", "~"
String atext = "a-zA-Z0-9\\u0021\\u0023\\u0024\\u0025\\u0026\\u0027\\u002a"
+ "\\u002b\\u002d\\u002f\\u003d\\u003f\\u005e\\u005f\\u0060\\u007b"
+ "\\u007c\\u007d\\u007e";
Pattern regex = Pattern.compile("^["+atext+"]+(\\u002e+["+atext+"]+)*$");
Matcher matcher = regex.matcher(localPart);
if (matcher.find()) {
result = true;
} else {
// Try quoted string format
// Quoted-string characters are: DQUOTE *([FWS] qtext/quoted-pair) [FWS] DQUOTE
// qtext: Non white space controls, and the rest of the US-ASCII characters not
// including "\" or the quote character
String noWsCtl = "\\u0001-\\u0008\\u000b\\u000c\\u000e-\\u001f\\u007f";
String qText = noWsCtl + "\\u0021\\u0023-\\u005b\\u005d-\\u007e";
String ws = "\\u0020\\u0009";
regex = Pattern.compile("^\\u0022(["+ws+qText+"])*["+ws+"]?\\u0022$");
matcher = regex.matcher(localPart);
if (matcher.find()) {
result = true;
} else {
addMessage("enterValidEmail", "email.AddressDotAtom");
addMessage("enterValidEmail", "email.AddressQuotedString");
addMessage("enterValidEmail", "email.AddressInvalidLocalPart");
}
}
return result;
}
private void addMessage(String detail, String summary) {
String detailMsg = bundle.getString(detail);
String summaryMsg = bundle.getString(summary);
messages.add(new FacesMessage(FacesMessage.SEVERITY_ERROR, summaryMsg, detailMsg));
}
private void setOptions(UIComponent component) {
Boolean domainOption = Boolean.valueOf((String) component.getAttributes().get("domain"));
//domain = (domainOption == null) ? true : domainOption.booleanValue();
}
}
With a hostname validator as follows:
#FacesValidator("hostNameValidator")
public class HostnameValidator implements Validator {
private Locale locale;
private ResourceBundle bundle;
private List<FacesMessage> messages;
private boolean checkTld = true;
private boolean allowLocal = false;
private boolean allowDNS = true;
private String tld;
private String[] validTlds = {"ac", "ad", "ae", "aero", "af", "ag", "ai",
"al", "am", "an", "ao", "aq", "ar", "arpa", "as", "asia", "at", "au",
"aw", "ax", "az", "ba", "bb", "bd", "be", "bf", "bg", "bh", "bi", "biz",
"bj", "bm", "bn", "bo", "br", "bs", "bt", "bv", "bw", "by", "bz", "ca",
"cat", "cc", "cd", "cf", "cg", "ch", "ci", "ck", "cl", "cm", "cn", "co",
"com", "coop", "cr", "cu", "cv", "cx", "cy", "cz", "de", "dj", "dk",
"dm", "do", "dz", "ec", "edu", "ee", "eg", "er", "es", "et", "eu", "fi",
"fj", "fk", "fm", "fo", "fr", "ga", "gb", "gd", "ge", "gf", "gg", "gh",
"gi", "gl", "gm", "gn", "gov", "gp", "gq", "gr", "gs", "gt", "gu", "gw",
"gy", "hk", "hm", "hn", "hr", "ht", "hu", "id", "ie", "il", "im", "in",
"info", "int", "io", "iq", "ir", "is", "it", "je", "jm", "jo", "jobs",
"jp", "ke", "kg", "kh", "ki", "km", "kn", "kp", "kr", "kw", "ky", "kz",
"la", "lb", "lc", "li", "lk", "lr", "ls", "lt", "lu", "lv", "ly", "ma",
"mc", "md", "me", "mg", "mh", "mil", "mk", "ml", "mm", "mn", "mo",
"mobi", "mp", "mq", "mr", "ms", "mt", "mu", "museum", "mv", "mw", "mx",
"my", "mz", "na", "name", "nc", "ne", "net", "nf", "ng", "ni", "nl",
"no", "np", "nr", "nu", "nz", "om", "org", "pa", "pe", "pf", "pg", "ph",
"pk", "pl", "pm", "pn", "pr", "pro", "ps", "pt", "pw", "py", "qa", "re",
"ro", "rs", "ru", "rw", "sa", "sb", "sc", "sd", "se", "sg", "sh", "si",
"sj", "sk", "sl", "sm", "sn", "so", "sr", "st", "su", "sv", "sy", "sz",
"tc", "td", "tel", "tf", "tg", "th", "tj", "tk", "tl", "tm", "tn", "to",
"tp", "tr", "travel", "tt", "tv", "tw", "tz", "ua", "ug", "uk", "um",
"us", "uy", "uz", "va", "vc", "ve", "vg", "vi", "vn", "vu", "wf", "ws",
"ye", "yt", "yu", "za", "zm", "zw"};
private Map<String, Map<Integer, Integer>> idnLength;
private void init() {
Map<Integer, Integer> biz = new HashMap<Integer, Integer>();
biz.put(5, 17);
biz.put(11, 15);
biz.put(12, 20);
Map<Integer, Integer> cn = new HashMap<Integer, Integer>();
cn.put(1, 20);
Map<Integer, Integer> com = new HashMap<Integer, Integer>();
com.put(3, 17);
com.put(5, 20);
Map<Integer, Integer> hk = new HashMap<Integer, Integer>();
hk.put(1, 15);
Map<Integer, Integer> info = new HashMap<Integer, Integer>();
info.put(4, 17);
Map<Integer, Integer> kr = new HashMap<Integer, Integer>();
kr.put(1, 17);
Map<Integer, Integer> net = new HashMap<Integer, Integer>();
net.put(3, 17);
net.put(5, 20);
Map<Integer, Integer> org = new HashMap<Integer, Integer>();
org.put(6, 17);
Map<Integer, Integer> tw = new HashMap<Integer, Integer>();
tw.put(1, 20);
Map<Integer, Integer> idn1 = new HashMap<Integer, Integer>();
idn1.put(1, 20);
Map<Integer, Integer> idn2 = new HashMap<Integer, Integer>();
idn2.put(1, 20);
Map<Integer, Integer> idn3 = new HashMap<Integer, Integer>();
idn3.put(1, 20);
Map<Integer, Integer> idn4 = new HashMap<Integer, Integer>();
idn4.put(1, 20);
idnLength = new HashMap<String, Map<Integer, Integer>>();
idnLength.put("BIZ", biz);
idnLength.put("CN", cn);
idnLength.put("COM", com);
idnLength.put("HK", hk);
idnLength.put("INFO", info);
idnLength.put("KR", kr);
idnLength.put("NET", net);
idnLength.put("ORG", org);
idnLength.put("TW", tw);
idnLength.put("ایران", idn1);
idnLength.put("中国", idn2);
idnLength.put("公司", idn3);
idnLength.put("网络", idn4);
messages = new ArrayList<FacesMessage>();
}
public HostnameValidator() {
init();
}
#Override
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
String hostName = (String) value;
locale = context.getViewRoot().getLocale();
bundle = ResourceBundle.getBundle("com.myapp.resources.validationMessages", locale);
Pattern ipPattern = Pattern.compile("^[0-9a-f:\\.]*$", Pattern.CASE_INSENSITIVE);
Matcher ipMatcher = ipPattern.matcher(hostName);
if (ipMatcher.find()) {
addMessage("hostname.IpAddressNotAllowed");
throw new ValidatorException(messages);
}
boolean result = false;
// removes last dot (.) from hostname
hostName = hostName.replaceAll("(\\.)+$", "");
String[] domainParts = hostName.split("\\.");
boolean status = false;
// Check input against DNS hostname schema
if ((domainParts.length > 1) && (hostName.length() > 4) && (hostName.length() < 255)) {
status = false;
dowhile:
do {
// First check TLD
int lastIndex = domainParts.length - 1;
String domainEnding = domainParts[lastIndex];
Pattern tldRegex = Pattern.compile("([^.]{2,10})", Pattern.CASE_INSENSITIVE);
Matcher tldMatcher = tldRegex.matcher(domainEnding);
if (tldMatcher.find() || domainEnding.equals("ایران")
|| domainEnding.equals("中国")
|| domainEnding.equals("公司")
|| domainEnding.equals("网络")) {
// Hostname characters are: *(label dot)(label dot label); max 254 chars
// label: id-prefix [*ldh{61} id-prefix]; max 63 chars
// id-prefix: alpha / digit
// ldh: alpha / digit / dash
// Match TLD against known list
tld = (String) tldMatcher.group(1).toLowerCase().trim();
if (checkTld == true) {
boolean foundTld = false;
for (int i = 0; i < validTlds.length; i++) {
if (tld.equals(validTlds[i])) {
foundTld = true;
}
}
if (foundTld == false) {
status = false;
addMessage("hostname.UnknownTld");
break dowhile;
}
}
/**
* Match against IDN hostnames
* Note: Keep label regex short to avoid issues with long patterns when matching IDN hostnames
*/
List<String> regexChars = getIdnRegexChars();
// Check each hostname part
int check = 0;
for (String domainPart : domainParts) {
// Decode Punycode domainnames to IDN
if (domainPart.indexOf("xn--") == 0) {
domainPart = decodePunycode(domainPart.substring(4));
}
// Check dash (-) does not start, end or appear in 3rd and 4th positions
if (domainPart.indexOf("-") == 0
|| (domainPart.length() > 2 && domainPart.indexOf("-", 2) == 2 && domainPart.indexOf("-", 3) == 3)
|| (domainPart.indexOf("-") == (domainPart.length() - 1))) {
status = false;
addMessage("hostname.DashCharacter");
break dowhile;
}
// Check each domain part
boolean checked = false;
for (int key = 0; key < regexChars.size(); key++) {
String regexChar = regexChars.get(key);
Pattern regex = Pattern.compile(regexChar);
Matcher regexMatcher = regex.matcher(domainPart);
status = regexMatcher.find();
if (status) {
int length = 63;
if (idnLength.containsKey(tld.toUpperCase())
&& idnLength.get(tld.toUpperCase()).containsKey(key)) {
length = idnLength.get(tld.toUpperCase()).get(key);
}
int utf8Length;
try {
utf8Length = domainPart.getBytes("UTF8").length;
if (utf8Length > length) {
addMessage("hostname.InvalidHostname");
} else {
checked = true;
break;
}
} catch (UnsupportedEncodingException ex) {
Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
if (checked) {
++check;
}
}
// If one of the labels doesn't match, the hostname is invalid
if (check != domainParts.length) {
status = false;
addMessage("hostname.InvalidHostnameSchema");
}
} else {
// Hostname not long enough
status = false;
addMessage("hostname.UndecipherableTld");
}
} while (false);
if (status == true && allowDNS) {
result = true;
}
} else if (allowDNS == true) {
addMessage("hostname.InvalidHostname");
throw new ValidatorException(messages);
}
// Check input against local network name schema;
Pattern regexLocal = Pattern.compile("^(([a-zA-Z0-9\\x2d]{1,63}\\x2e)*[a-zA-Z0-9\\x2d]{1,63}){1,254}$", Pattern.CASE_INSENSITIVE);
boolean checkLocal = regexLocal.matcher(hostName).find();
if (allowLocal && !status) {
if (checkLocal) {
result = true;
} else {
// If the input does not pass as a local network name, add a message
result = false;
addMessage("hostname.InvalidLocalName");
}
}
// If local network names are not allowed, add a message
if (checkLocal && !allowLocal && !status) {
result = false;
addMessage("hostname.LocalNameNotAllowed");
}
if (result == false) {
throw new ValidatorException(messages);
}
}
private void addMessage(String msg) {
String bundlMsg = bundle.getString(msg);
messages.add(new FacesMessage(FacesMessage.SEVERITY_ERROR, bundlMsg, bundlMsg));
}
/**
* Returns a list of regex patterns for the matched TLD
* #param tld
* #return
*/
private List<String> getIdnRegexChars() {
List<String> regexChars = new ArrayList<String>();
regexChars.add("^[a-z0-9\\x2d]{1,63}$");
Document doc = null;
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
try {
InputStream validIdns = getClass().getClassLoader().getResourceAsStream("com/myapp/resources/validIDNs_1.xml");
DocumentBuilder builder = factory.newDocumentBuilder();
doc = builder.parse(validIdns);
doc.getDocumentElement().normalize();
} catch (SAXException ex) {
Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
} catch (ParserConfigurationException ex) {
Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
}
// prepare XPath
XPath xpath = XPathFactory.newInstance().newXPath();
NodeList nodes = null;
String xpathRoute = "//idn[tld=\'" + tld.toUpperCase() + "\']/pattern/text()";
try {
XPathExpression expr;
expr = xpath.compile(xpathRoute);
Object res = expr.evaluate(doc, XPathConstants.NODESET);
nodes = (NodeList) res;
} catch (XPathExpressionException ex) {
Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
}
for (int i = 0; i < nodes.getLength(); i++) {
regexChars.add(nodes.item(i).getNodeValue());
}
return regexChars;
}
/**
* Decode Punycode string
* #param encoded
* #return
*/
private String decodePunycode(String encoded) {
Pattern regex = Pattern.compile("([^a-z0-9\\x2d]{1,10})", Pattern.CASE_INSENSITIVE);
Matcher matcher = regex.matcher(encoded);
boolean found = matcher.find();
if (encoded.isEmpty() || found) {
// no punycode encoded string, return as is
addMessage("hostname.CannotDecodePunycode");
throw new ValidatorException(messages);
}
int separator = encoded.lastIndexOf("-");
List<Integer> decoded = new ArrayList<Integer>();
if (separator > 0) {
for (int x = 0; x < separator; ++x) {
decoded.add((int) encoded.charAt(x));
}
} else {
addMessage("hostname.CannotDecodePunycode");
throw new ValidatorException(messages);
}
int lengthd = decoded.size();
int lengthe = encoded.length();
// decoding
boolean init = true;
int base = 72;
int index = 0;
int ch = 0x80;
int indexeStart = (separator == 1) ? (separator + 1) : 0;
for (int indexe = indexeStart; indexe < lengthe; ++lengthd) {
int oldIndex = index;
int pos = 1;
for (int key = 36; true; key += 36) {
int hex = (int) encoded.charAt(indexe++);
int digit = (hex - 48 < 10) ? hex - 22
: ((hex - 65 < 26) ? hex - 65
: ((hex - 97 < 26) ? hex - 97
: 36));
index += digit * pos;
int tag = (key <= base) ? 1 : ((key >= base + 26) ? 26 : (key - base));
if (digit < tag) {
break;
}
pos = (int) (pos * (36 - tag));
}
int delta = (int) (init ? ((index - oldIndex) / 700) : ((index - oldIndex) / 2));
delta += (int) (delta / (lengthd + 1));
int key;
for (key = 0; delta > 910; key += 36) {
delta = (int) (delta / 35);
}
base = (int) (key + 36 * delta / (delta + 38));
init = false;
ch += (int) (index / (lengthd + 1));
index %= (lengthd + 1);
if (lengthd > 0) {
for (int i = lengthd; i > index; i--) {
decoded.set(i, decoded.get(i - 1));
}
}
decoded.set(index++, ch);
}
// convert decoded ucs4 to utf8 string
StringBuilder sb = new StringBuilder();
for (int i = 0; i < decoded.size(); i++) {
int value = decoded.get(i);
if (value < 128) {
sb.append((char) value);
} else if (value < (1 << 11)) {
sb.append((char) (192 + (value >> 6)));
sb.append((char) (128 + (value & 63)));
} else if (value < (1 << 16)) {
sb.append((char) (224 + (value >> 12)));
sb.append((char) (128 + ((value >> 6) & 63)));
sb.append((char) (128 + (value & 63)));
} else if (value < (1 << 21)) {
sb.append((char) (240 + (value >> 18)));
sb.append((char) (128 + ((value >> 12) & 63)));
sb.append((char) (128 + ((value >> 6) & 63)));
sb.append((char) (128 + (value & 63)));
} else {
addMessage("hostname.CannotDecodePunycode");
throw new ValidatorException(messages);
}
}
return sb.toString();
}
/**
* Eliminates empty values from input array
* #param data
* #return
*/
private String[] verifyArray(String[] data) {
List<String> result = new ArrayList<String>();
for (String s : data) {
if (!s.equals("")) {
result.add(s);
}
}
return result.toArray(new String[result.size()]);
}
}
And a validIDNs.xml with regex patterns for the different tlds (too big to include:)
<idnlist>
<idn>
<tld>AC</tld>
<pattern>^[\u002d0-9a-zà-öø-ÿāăąćĉċčďđēėęěĝġģĥħīįĵķĺļľŀłńņňŋőœŕŗřśŝşšţťŧūŭůűųŵŷźżž]{1,63}$</pattern>
</idn>
<idn>
<tld>AR</tld>
<pattern>^[\u002d0-9a-zà-ãç-êìíñ-õü]{1,63}$</pattern>
</idn>
<idn>
<tld>AS</tld>
<pattern>/^[\u002d0-9a-zà-öø-ÿāăąćĉċčďđēĕėęěĝğġģĥħĩīĭįıĵķĸĺļľłńņňŋōŏőœŕŗřśŝşšţťŧũūŭůűųŵŷźż]{1,63}$</pattern>
</idn>
<idn>
<tld>AT</tld>
<pattern>/^[\u002d0-9a-zà-öø-ÿœšž]{1,63}$</pattern>
</idn>
<idn>
<tld>BIZ</tld>
<pattern>^[\u002d0-9a-zäåæéöøü]{1,63}$</pattern>
<pattern>^[\u002d0-9a-záéíñóúü]{1,63}$</pattern>
<pattern>^[\u002d0-9a-záéíóöúüőű]{1,63}$</pattern>
</id>
</idlist>

public class Validations {
private Pattern regexPattern;
private Matcher regMatcher;
public String validateEmailAddress(String emailAddress) {
regexPattern = Pattern.compile("^[(a-zA-Z-0-9-\\_\\+\\.)]+#[(a-z-A-z)]+\\.[(a-zA-z)]{2,3}$");
regMatcher = regexPattern.matcher(emailAddress);
if(regMatcher.matches()) {
return "Valid Email Address";
} else {
return "Invalid Email Address";
}
}
public String validateMobileNumber(String mobileNumber) {
regexPattern = Pattern.compile("^\\+[0-9]{2,3}+-[0-9]{10}$");
regMatcher = regexPattern.matcher(mobileNumber);
if(regMatcher.matches()) {
return "Valid Mobile Number";
} else {
return "Invalid Mobile Number";
}
}
public static void main(String[] args) {
String emailAddress = "suryaprakash.pisay#gmail.com";
String mobileNumber = "+91-9986571622";
Validations validations = new Validations();
System.out.println(validations.validateEmailAddress(emailAddress));
System.out.println(validations.validateMobileNumber(mobileNumber));
}
}

If you're looking to verify whether an email address is valid, then VRFY will get you some of the way. I've found it's useful for validating intranet addresses (that is, email addresses for internal sites). However it's less useful for internet mail servers (see the caveats at the top of this page)

Although there are many alternatives to Apache commons, their implementations are rudimentary at best (like Apache commons' implementation itself) and even dead wrong in other cases.
I'd also stay away from so called simple 'non-restrictive' regex; there's no such thing. For example # is allowed multiple times depending on context, how do you know the required one is there? Simple regex won't understand it, even though the email should be valid. Anything more complex becomes error-prone or even contain hidden performance killers. How are you going to maintain something like this?
The only comprehensive RFC compliant regex based validator I'm aware of is email-rfc2822-validator with its 'refined' regex appropriately named Dragons.java. It supports only the older RFC-2822 spec though, although appropriate enough for modern needs (RFC-5322 updates it in areas already out of scope for daily use cases).
But really what you want is a lexer that properly parses a string and breaks it up into the component structure according to the RFC grammar. EmailValidator4J seems promising in that regard, but is still young and limited.
Another option you have is using a webservice such as Mailgun's battle-tested validation webservice or Mailboxlayer API (just took the first Google results). It is not strictly RFC compliant, but works well enough for modern needs.

What do you want to validate? The email address?
The email address can only be checked for its format conformance. See the standard: RFC2822. Best way to do that is a regular expression. You will never know if really exists without sending an email.
I checked the commons validator. It contains an org.apache.commons.validator.EmailValidator class. Seems to be a good starting point.

Current Apache Commons Validator version is 1.3.1.
Class that validates is org.apache.commons.validator.EmailValidator. It has an import for org.apache.oro.text.perl.Perl5Util which is from a retired Jakarta ORO project.
BTW, I found that there is a 1.4 version, here are the API docs. On the site it says: "Last Published: 05 March 2008 | Version: 1.4-SNAPSHOT", but that's not final. Only way to build yourself (but this is a snapshot, not RELEASE) and use, or download from here. This means 1.4 has not been made final for three years (2008-2011). This is not in Apache's style.
I'm looking for a better option, but didn't find one that is very adopted. I want to use something that is well tested, don't want to hit any bugs.

You may also want to check for the length - emails are a maximum of 254 chars long. I use the apache commons validator and it doesn't check for this.

There don't seem to be any perfect libraries or ways to do this yourself, unless you have to time to send an email to the email address and wait for a response (this might not be an option though). I ended up using a suggestion from here http://blog.logichigh.com/2010/09/02/validating-an-e-mail-address/ and adjusting the code so it would work in Java.
public static boolean isValidEmailAddress(String email) {
boolean stricterFilter = true;
String stricterFilterString = "[A-Z0-9a-z._%+-]+#[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
String laxString = ".+#.+\\.[A-Za-z]{2}[A-Za-z]*";
String emailRegex = stricterFilter ? stricterFilterString : laxString;
java.util.regex.Pattern p = java.util.regex.Pattern.compile(emailRegex);
java.util.regex.Matcher m = p.matcher(email);
return m.matches();
}

This is the best method:
public static boolean isValidEmail(String enteredEmail){
String EMAIL_REGIX = "^[\\\\w!#$%&’*+/=?`{|}~^-]+(?:\\\\.[\\\\w!#$%&’*+/=?`{|}~^-]+)*#(?:[a-zA-Z0-9-]+\\\\.)+[a-zA-Z]{2,6}$";
Pattern pattern = Pattern.compile(EMAIL_REGIX);
Matcher matcher = pattern.matcher(enteredEmail);
return ((!enteredEmail.isEmpty()) && (enteredEmail!=null) && (matcher.matches()));
}
Sources:-
http://howtodoinjava.com/2014/11/11/java-regex-validate-email-address/
http://www.rfc-editor.org/rfc/rfc5322.txt

Another option is use the Hibernate email validator, using the annotation #Email or using the validator class programatically, like:
import org.hibernate.validator.internal.constraintvalidators.hv.EmailValidator;
class Validator {
// code
private boolean isValidEmail(String email) {
EmailValidator emailValidator = new EmailValidator();
return emailValidator.isValid(email, null);
}
}

Heres my pragmatic approach, where I just want reasonable distinct blah#domain addresses using the allowable characters from the RFC. Addresses must be converted to lowercase beforehand.
public class EmailAddressValidator {
private static final String domainChars = "a-z0-9\\-";
private static final String atomChars = "a-z0-9\\Q!#$%&'*+-/=?^_`{|}~\\E";
private static final String emailRegex = "^" + dot(atomChars) + "#" + dot(domainChars) + "$";
private static final Pattern emailPattern = Pattern.compile(emailRegex);
private static String dot(String chars) {
return "[" + chars + "]+(?:\\.[" + chars + "]+)*";
}
public static boolean isValidEmailAddress(String address) {
return address != null && emailPattern.matcher(address).matches();
}
}

Resources