How do you connect to a MySQL database in Java?
When I try, I get
java.sql.SQLException: No suitable driver found for jdbc:mysql://database/table
at java.sql.DriverManager.getConnection(DriverManager.java:689)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
Or
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
Or
java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
Here's a step by step explanation how to install MySQL and JDBC and how to use it:
Download and install the MySQL server. Just do it the usual way. Remember the port number whenever you've changed it. It's by default 3306.
Download the JDBC driver and put in classpath, extract the ZIP file and put the containing JAR file in the classpath. The vendor-specific JDBC driver is a concrete implementation of the JDBC API (tutorial here).
If you're using an IDE like Eclipse or Netbeans, then you can add it to the classpath by adding the JAR file as Library to the Build Path in project's properties.
If you're doing it "plain vanilla" in the command console, then you need to specify the path to the JAR file in the -cp or -classpath argument when executing your Java application.
java -cp .;/path/to/mysql-connector.jar com.example.YourClass
The . is just there to add the current directory to the classpath as well so that it can locate com.example.YourClass and the ; is the classpath separator as it is in Windows. In Unix and clones : should be used.
Create a database in MySQL. Let's create a database javabase. You of course want World Domination, so let's use UTF-8 as well.
CREATE DATABASE javabase DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci;
Create a user for Java and grant it access. Simply because using root is a bad practice.
CREATE USER 'java'#'localhost' IDENTIFIED BY 'password';
GRANT ALL ON javabase.* TO 'java'#'localhost' IDENTIFIED BY 'password';
Yes, java is the username and password is the password here.
Determine the JDBC URL. To connect the MySQL database using Java you need an JDBC URL in the following syntax:
jdbc:mysql://hostname:port/databasename
hostname: The hostname where MySQL server is installed. If it's installed at the same machine where you run the Java code, then you can just use localhost. It can also be an IP address like 127.0.0.1. If you encounter connectivity problems and using 127.0.0.1 instead of localhost solved it, then you've a problem in your network/DNS/hosts config.
port: The TCP/IP port where MySQL server listens on. This is by default 3306.
databasename: The name of the database you'd like to connect to. That's javabase.
So the final URL should look like:
jdbc:mysql://localhost:3306/javabase
Test the connection to MySQL using Java. Create a simple Java class with a main() method to test the connection.
String url = "jdbc:mysql://localhost:3306/javabase";
String username = "java";
String password = "password";
System.out.println("Connecting database...");
try (Connection connection = DriverManager.getConnection(url, username, password)) {
System.out.println("Database connected!");
} catch (SQLException e) {
throw new IllegalStateException("Cannot connect the database!", e);
}
If you get a SQLException: No suitable driver, then it means that either the JDBC driver wasn't autoloaded at all or that the JDBC URL is wrong (i.e. it wasn't recognized by any of the loaded drivers). Normally, a JDBC 4.0 driver should be autoloaded when you just drop it in runtime classpath. To exclude one and other, you can always manually load it as below:
System.out.println("Loading driver...");
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Driver loaded!");
} catch (ClassNotFoundException e) {
throw new IllegalStateException("Cannot find the driver in the classpath!", e);
}
Note that the newInstance() call is not needed here. It's just to fix the old and buggy org.gjt.mm.mysql.Driver. Explanation here. If this line throws ClassNotFoundException, then the JAR file containing the JDBC driver class is simply not been placed in the classpath.
Note that you don't need to load the driver everytime before connecting. Just only once during application startup is enough.
If you get a SQLException: Connection refused or Connection timed out or a MySQL specific CommunicationsException: Communications link failure, then it means that the DB isn't reachable at all. This can have one or more of the following causes:
IP address or hostname in JDBC URL is wrong.
Hostname in JDBC URL is not recognized by local DNS server.
Port number is missing or wrong in JDBC URL.
DB server is down.
DB server doesn't accept TCP/IP connections.
DB server has run out of connections.
Something in between Java and DB is blocking connections, e.g. a firewall or proxy.
To solve the one or the other, follow the following advices:
Verify and test them with ping.
Refresh DNS or use IP address in JDBC URL instead.
Verify it based on my.cnf of MySQL DB.
Start the DB.
Verify if mysqld is started without the --skip-networking option.
Restart the DB and fix your code accordingly that it closes connections in finally.
Disable firewall and/or configure firewall/proxy to allow/forward the port.
Note that closing the Connection is extremely important. If you don't close connections and keep getting a lot of them in a short time, then the database may run out of connections and your application may break. Always acquire the Connection in a try-with-resources statement. Or if you're not on Java 7 yet, explicitly close it in finally of a try-finally block. Closing in finally is just to ensure that it get closed as well in case of an exception. This also applies to Statement, PreparedStatement and ResultSet.
That was it as far the connectivity concerns. You can find here a more advanced tutorial how to load and store fullworthy Java model objects in a database with help of a basic DAO class.
Using a Singleton Pattern for the DB connection is a bad approach. See among other questions: Is it safe to use a static java.sql.Connection instance in a multithreaded system?. This is a #1 starters mistake.
DriverManager is a fairly old way of doing things. The better way is to get a DataSource, either by looking one up that your app server container already configured for you:
Context context = new InitialContext();
DataSource dataSource = (DataSource) context.lookup("java:comp/env/jdbc/myDB");
or instantiating and configuring one from your database driver directly:
MysqlDataSource dataSource = new MysqlDataSource();
dataSource.setUser("scott");
dataSource.setPassword("tiger");
dataSource.setServerName("myDBHost.example.org");
and then obtain connections from it, same as above:
Connection conn = dataSource.getConnection();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT ID FROM USERS");
...
rs.close();
stmt.close();
conn.close();
Initialize database constants
Create constant properties database username, password, URL and drivers, polling limit etc.
// init database constants
// com.mysql.jdbc.Driver
private static final String DATABASE_DRIVER = "com.mysql.cj.jdbc.Driver";
private static final String DATABASE_URL = "jdbc:mysql://localhost:3306/database_name";
private static final String USERNAME = "root";
private static final String PASSWORD = "";
private static final String MAX_POOL = "250"; // set your own limit
Initialize Connection and Properties
Once the connection is established, it is better to store for reuse purpose.
// init connection object
private Connection connection;
// init properties object
private Properties properties;
Create Properties
The properties object hold the connection information, check if it is already set.
// create properties
private Properties getProperties() {
if (properties == null) {
properties = new Properties();
properties.setProperty("user", USERNAME);
properties.setProperty("password", PASSWORD);
properties.setProperty("MaxPooledStatements", MAX_POOL);
}
return properties;
}
Connect the Database
Now connect to database using the constants and properties initialized.
// connect database
public Connection connect() {
if (connection == null) {
try {
Class.forName(DATABASE_DRIVER);
connection = DriverManager.getConnection(DATABASE_URL, getProperties());
} catch (ClassNotFoundException | SQLException e) {
// Java 7+
e.printStackTrace();
}
}
return connection;
}
Disconnect the database
Once you are done with database operations, just close the connection.
// disconnect database
public void disconnect() {
if (connection != null) {
try {
connection.close();
connection = null;
} catch (SQLException e) {
e.printStackTrace();
}
}
}
Everything together
Use this class MysqlConnect directly after changing database_name, username and password etc.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
public class MysqlConnect {
// init database constants
private static final String DATABASE_DRIVER = "com.mysql.cj.jdbc.Driver";
private static final String DATABASE_URL = "jdbc:mysql://localhost:3306/database_name";
private static final String USERNAME = "root";
private static final String PASSWORD = "";
private static final String MAX_POOL = "250";
// init connection object
private Connection connection;
// init properties object
private Properties properties;
// create properties
private Properties getProperties() {
if (properties == null) {
properties = new Properties();
properties.setProperty("user", USERNAME);
properties.setProperty("password", PASSWORD);
properties.setProperty("MaxPooledStatements", MAX_POOL);
}
return properties;
}
// connect database
public Connection connect() {
if (connection == null) {
try {
Class.forName(DATABASE_DRIVER);
connection = DriverManager.getConnection(DATABASE_URL, getProperties());
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
return connection;
}
// disconnect database
public void disconnect() {
if (connection != null) {
try {
connection.close();
connection = null;
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
How to Use?
Initialize the database class.
// !_ note _! this is just init
// it will not create a connection
MysqlConnect mysqlConnect = new MysqlConnect();
Somewhere else in your code ...
String sql = "SELECT * FROM `stackoverflow`";
try {
PreparedStatement statement = mysqlConnect.connect().prepareStatement(sql);
... go on ...
... go on ...
... DONE ....
} catch (SQLException e) {
e.printStackTrace();
} finally {
mysqlConnect.disconnect();
}
This is all :) If anything to improve edit it! Hope this is helpful.
String url = "jdbc:mysql://127.0.0.1:3306/yourdatabase";
String user = "username";
String password = "password";
// Load the Connector/J driver
Class.forName("com.mysql.jdbc.Driver").newInstance();
// Establish connection to MySQL
Connection conn = DriverManager.getConnection(url, user, password);
Here's the very minimum you need to get data out of a MySQL database:
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection
("jdbc:mysql://localhost:3306/foo", "root", "password");
Statement stmt = conn.createStatement();
stmt.execute("SELECT * FROM `FOO.BAR`");
stmt.close();
conn.close();
Add exception handling, configuration etc. to taste.
you need to have mysql connector jar in your classpath.
in Java JDBC API makes everything with databases. using JDBC we can write Java applications to
1. Send queries or update SQL to DB(any relational Database)
2. Retrieve and process the results from DB
with below three steps we can able to retrieve data from any Database
Connection con = DriverManager.getConnection(
"jdbc:myDriver:DatabaseName",
dBuserName,
dBuserPassword);
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM Table");
while (rs.next()) {
int x = rs.getInt("a");
String s = rs.getString("b");
float f = rs.getFloat("c");
}
You can see all steps to connect MySQL database from Java application here. For other database, you just need to change the driver in first step only. Please make sure that you provide right path to database and correct username and password.
Visit http://apekshit.com/t/51/Steps-to-connect-Database-using-JAVA
MySQL JDBC Connection with useSSL.
private String db_server = BaseMethods.getSystemData("db_server");
private String db_user = BaseMethods.getSystemData("db_user");
private String db_password = BaseMethods.getSystemData("db_password");
private String connectToDb() throws Exception {
String jdbcDriver = "com.mysql.jdbc.Driver";
String dbUrl = "jdbc:mysql://" + db_server +
"?verifyServerCertificate=false" +
"&useSSL=true" +
"&requireSSL=true";
System.setProperty(jdbcDriver, "");
Class.forName(jdbcDriver).newInstance();
Connection conn = DriverManager.getConnection(dbUrl, db_user, db_password);
Statement statement = conn.createStatement();
String query = "SELECT EXTERNAL_ID FROM offer_letter where ID =" + "\"" + letterID + "\"";
ResultSet resultSet = statement.executeQuery(query);
resultSet.next();
return resultSet.getString(1);
}
Short and Sweet code.
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Driver Loaded");
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/testDB","root","");
//Database Name - testDB, Username - "root", Password - ""
System.out.println("Connected...");
} catch(Exception e) {
e.printStackTrace();
}
For SQL server 2012
try {
String url = "jdbc:sqlserver://KHILAN:1433;databaseName=testDB;user=Khilan;password=Tuxedo123";
//KHILAN is Host and 1433 is port number
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
System.out.println("Driver Loaded");
conn = DriverManager.getConnection(url);
System.out.println("Connected...");
} catch(Exception e) {
e.printStackTrace();
}
Connection I was using some time ago, it was looking like the easiest way, but also there were recommendation to make there if statement- exactly
Connection con = DriverManager.getConnection(
"jdbc:myDriver:DatabaseName",
dBuserName,
dBuserPassword);
if (con != null){
//..handle your code there
}
Or something like in that way :)
Probably there's some case, while getConnection can return null :)
HOW
To set up the Driver to run a quick sample
1. Go to https://dev.mysql.com/downloads/connector/j/, get the latest version of Connector/J
2. Remember to set the classpath to include the path of the connector jar file.
If we don't set it correctly, below errors can occur:
No suitable driver found for jdbc:mysql://127.0.0.1:3306/msystem_development
java.lang.ClassNotFoundException: com.mysql.jdbc:Driver
To set up the CLASSPATH
Method 1: set the CLASSPATH variable.
export CLASSPATH=".:mysql-connector-java-VERSION.jar"
java MyClassFile
In the above command, I have set the CLASSPATH to the current folder and mysql-connector-java-VERSION.jar file. So when the java MyClassFile command executed, java application launcher will try to load all the Java class in CLASSPATH.
And it found the Drive class => BOOM errors was gone.
Method 2:
java -cp .:mysql-connector-java-VERSION.jar MyClassFile
Note: Class.forName("com.mysql.jdbc.Driver"); This is deprecated at this moment 2019 Apr.
Hope this can help someone!
MySql JDBC Connection:
Class.forName("com.mysql.jdbc.Driver");
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/DatabaseName","Username","Password");
Statement stmt=con.createStatement();
stmt = con.createStatement();
ResultSet rs=stmt.executeQuery("Select * from Table");
Short Code
public class DB {
public static Connection c;
public static Connection getConnection() throws Exception {
if (c == null) {
Class.forName("com.mysql.jdbc.Driver");
c =DriverManager.getConnection("jdbc:mysql://localhost:3306/DATABASE", "USERNAME", "Password");
}
return c;
}
// Send data TO Database
public static void setData(String sql) throws Exception {
DB.getConnection().createStatement().executeUpdate(sql);
}
// Get Data From Database
public static ResultSet getData(String sql) throws Exception {
ResultSet rs = DB.getConnection().createStatement().executeQuery(sql);
return rs;
}
}
Download JDBC Driver
Download link (Select platform independent): https://dev.mysql.com/downloads/connector/j/
Move JDBC Driver to C Drive
Unzip the files and move to C:\ drive. Your driver path should be like C:\mysql-connector-java-8.0.19\mysql-connector-java-8.0.19
Run Your Java
java -cp "C:\mysql-connector-java-8.0.19\mysql-connector-java-8.0.19\mysql-connector-java-8.0.19.jar" testMySQL.java
testMySQL.java
import java.sql.*;
import java.io.*;
public class testMySQL {
public static void main(String[] args) {
// TODO Auto-generated method stub
try
{
Class.forName("com.mysql.cj.jdbc.Driver");
Connection con=DriverManager.getConnection(
"jdbc:mysql://localhost:3306/db?useSSL=false&useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC","root","");
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery("show databases;");
System.out.println("Connected");
}
catch(Exception e)
{
System.out.println(e);
}
}
}
Objective
I'm trying to write to Oracle's ADWC (basically oracle database) from a Spark application running on Yarn. The only way to connect to this database is by using an Oracle Wallet file, which is basically a Java keystore.
Problem
The problem arises when the JDBC driver tries to read the wallet from HDFS. If I include the hdfs:// prefix the parser in the JDBC driver throws an error and if I don't then it cannot find the file.
Previous Attempts
including the directory in the connect string (prefixed and non) jdbc:oracle:thin:#luigi_low?TNS_ADMIN=/user/spark/wallet_LUIGI
including the directory as an spark.driver.extraJavaOptions with -Doracle.net.tns_admin and -Doracle.net.wallet_location
All the code is on GitHub, and specifically, the error messages are here https://github.com/sblack4/kafka-scala-jdbc/blob/master/ERROR.md
I've got a working example of the same connection here https://github.com/sblack4/scala-jdbc-adwc
help me StackOverflow. you are my only hope
If you need any more clarification don't hesitate :)
update (SparkFiles attempt)
the code is on a separate branch of the same repository, https://github.com/sblack4/kafka-scala-jdbc/tree/sparkfiles
This error message mystifies me as it seems my JDBC library has stopped trying to read the wallet files. It may be unrelated to the previous problem
Exception in thread "main" java.sql.SQLRecoverableException: IO Error: Invalid connection string format, a valid format is: "host:port:sid"
I've deleted the other JDBC libraries from my classpath through Ambari as this error could be related to spark picking up an older version of my JDBC library
Here's some code that will help diagnose what the issues is.
It checks and configures everything required to connect.
JDBC Driver version
JCE Installed
Classpath dependencies
Configures
tns_admin
ssl settings
trust/key stores
This is a slimmed down version of what's in sqldev/sqlcl
import java.security.NoSuchAlgorithmException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Collections;
import java.util.Properties;
import javax.crypto.Cipher;
import oracle.jdbc.OracleConnection;
public class JDBCTest {
public static void fail(String msg){
System.err.println(String.join("", Collections.nCopies(20, "*")));
System.err.println(msg);
System.err.println(String.join("", Collections.nCopies(20, "*")));
System.exit(1);
}
public static void main(String[] args) throws SQLException {
System.out.println("JDBC Driver Version:" + oracle.jdbc.OracleDriver.getDriverVersion());
// Check JDBC Driver Version
if (!oracle.jdbc.OracleDriver.getDriverVersion().startsWith("18.")) {
fail(" DRIVER TOOO OLD!!!");
}
// Check JCE Installed
int maxKeySize = 0;
try {
maxKeySize = Cipher.getMaxAllowedKeyLength("AES");
} catch (NoSuchAlgorithmException e) {
}
if (maxKeySize < 129 ) {
fail(" JCE Policy not unlimited!!!");
}
// Check Classpath
String cp = System.getProperty("java.class.path");
String[] cpFiles = {"ojdbc8.jar","oraclepki.jar","osdt_cert.jar","osdt_core.jar"};
for (String file:cpFiles){
if ( cp.indexOf(file) == -1 ){
fail("CLASSPATH Missing:" + file);
}
}
// Wallet unziped location
String unzippedWalletLocation = "/Users/klrice/workspace/12.2JDBC/wallet";
String conString = "jdbc:oracle:thin:#sqldev_medium";
Properties props = new Properties();
props.setProperty("oracle.net.wallet_location",unzippedWalletLocation);
props.setProperty(OracleConnection.CONNECTION_PROPERTY_THIN_NET_CONNECT_TIMEOUT, "2000");
// unzipped includes a tnsnames.ora
props.setProperty("oracle.net.tns_admin",unzippedWalletLocation);
props.setProperty("javax.net.ssl.trustStore","truststore.jks");
props.setProperty("javax.net.ssl.trustStorePassword","<password>");
props.setProperty("javax.net.ssl.keyStore","keystore.jks");
props.setProperty("javax.net.ssl.keyStorePassword","<password>");
props.setProperty("oracle.net.ssl_server_dn_match","true");
props.setProperty("oracle.net.ssl_version","1.2");
props.setProperty("user", "ADMIN");
props.setProperty("password", "<password>");
try {
// now Connect
Connection conn = DriverManager.getConnection(conString,props);
} catch (Exception e){
e.printStackTrace();
fail(e.getLocalizedMessage());
}
System.out.println("SUCCESS!!");
}
}
Are you using 18.3 JDBC drivers? Passing TNS_ADMIN as part of the connection URL requires 18.3 JDBC driver. Also, are you attempting to connect within the corporate network. In that case, you will need to pass HTTPS_PROXY and HTTPS_PROXY_PORT in the connection URL. Let us know. Happy to help with the problem.
I'm new to phoenix and hbase.hbase table and phoenix view works well and i can fetch data through phoenix. when I access jdbc to phoenix,it stucks.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Phoenix {
private static String driver = "org.apache.phoenix.jdbc.PhoenixDriver";
public static void main(String[] args) throws SQLException {
try {
Class.forName(driver);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Statement stmt = null;
ResultSet rs = null;
System.out.println("start...");
Connection con = DriverManager.getConnection("jdbc:phoenix:[my_cloud_server_ip]:2181");
System.out.println(con);
con.close();
}
}
(only one zookeeper server has public internet ip,so i write this ip there,does it matters?)
it prints "start..." and no response any more
BUT when when the url is "jdbc:phoenix:ip:2181" or "jdbc:phoenix:ip:2181/hbase"
i got no response
when i add some other words ,for example "jdbc:phoenix:ip:2181/balabala"
i got NULL POINTER EXCEPTION
why ?
I hope u can understand what i say:)
Reproducing your example, I am getting a java.net.SocketTimeoutException after 60 seconds, caused by java.net.UnknownHostException: unknown host: <hostname_of_my_zk_server>. But maybe that's what you called "no response" if you were in a hurry (or if you have a custom hbase-site.xml with a larger timeout client-side).
This error seems like the one explained in this article (section Zookeeper at the end) :
As in our case CDH was running in a test VM, we encountered this issue: http://stackoverflow.com/questions/18428722/hbase-java-client-unknown-host-localhost-localdomain
That was worked around by adding localhost.localdomain to the existing /etc/hosts entry for cluster1, which was already pointing to the right IP address.
This answer on SO summarizes the solution.
Basically, you need to add an entry to your /etc/hosts client-side :
<my_cloud_server_ip> <hostname_of_my_cloud_server_ip>
Moreover, you need to have an hbase-site.xml client-side (you can use the one on your server as a basis).
How do I connect to CockroachDB in Java using JDBC, e.g. what are the parameters and format of the connection string?
You can see a full example of Cockroach using jdbc here, but here's the code snippet including the connection string:
import java.sql.*;
public static void main(String[] args)...{
Class.forName("org.postgresql.Driver");
Connection db = DriverManager.getConnection("jdbc:postgresql://127.0.0.1:26257/[your database]?sslmode=disable", "maxroach", "");
I have been trying to run this code for hours, to get no success. I have Oracle 11g Enterprise Edition. Does anyone know the code to get port number from sql * plus cmd prompt?
The code doesn't run and I am not able to view the output over eclipse. Please guide me.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class Testt {
public static void main(String[] args) throws Exception {
try{
//Driver registration
Class.forName("oracle.jdbc.driver.OracleDriver");
//Create connection
Connection c =DriverManager.getConnection("jdbc:oracle:thin:
#localhost:1521:EE","scott","tiger");
//Create statement
Statement stmt=c.createStatement();
//Execute query
ResultSet rs=stmt.executeQuery("select * from emp;");
while(rs.next())
{
System.out.println(rs.getInt(1)+" "+rs.getString(2));
}
c.close();
}
catch(Exception e){e.printStackTrace();}
}
}
Output:
java.sql.SQLException: Listener refused the connection with the following error:
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor