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);
}
}
}
I have an embedded H2 Database I'd like to put in the WEB-INF directory of a web application.
What is the proper way to refer to this in a JDBC url?
Ideally I'd like a solution that would work both for a WAR, and an expanded WAR (If possible).
Thank-you for your help!
FYI, I've tried the following:
jdbc:h2:/WEB-INF/data/myDB;CIPHER=AES
But this results in:
org.h2.jdbc.JdbcSQLException: A file path that is implicitly relative to the current working directory is not allowed in the database URL "jdbc:h2:/WEB-INF/data/myDB;CIPHER=AES". Use an absolute path, ~/name, ./name, or the baseDir setting instead. [90011-187]
Changing this to:
jdbc:h2:./WEB-INF/data/myDB;CIPHER=AES
Results in the following error, which clearly shows its trying to put my database in Tomcat's bin directory, rather than the true WEB-INF directory where I want it:
org.h2.jdbc.JdbcSQLException: Error while creating file "C:/Program Files/Apache Software Foundation/Tomcat 7.0/bin/WEB-INF" [90062-187]
I managed to make the embedded solution work without AES like this:
try {
Class.forName("org.h2.Driver");
Connection conn = DriverManager.getConnection(
"jdbc:h2:" + getServletContext().getRealPath("/") +
"/WEB-INF/data/myDB", "sa", "");
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM INFORMATION_SCHEMA.TABLES");
while (rs.next()) {
}
rs.close();
stmt.close();
conn.close();
} catch(SQLException e) {
} catch(ClassNotFoundException e) {
} finally {
}
This was tested with H2 1.3.176 on Tomcat8. It should work with H2 1.4 and CIPHER=AES provided the embedded database is already inside the war file I guess.
The idea is the following: you need to get the absolute path, and that deployment path may not be the same depending on how you deployed the war file.
So we need to use the servlet context and request the real path. For this we use getServletContext().getRealPath("/") and append /WEB-INF/data/myDB to it as per your needs.
I did not test the CIPHER=AES part as I've never used it.
Update:
Getting a good reference to the servlet context is tricky. One could use a raw request, get the underlying session and then get to the servlet context.
But it would be good to have the embedded H2 database opened as soon as the application is deployed/started in Tomcat, and closed properly as soon as the application is stopped.
In order to perform that, the use of a listener is needed. Here's what I propose as an update to my previous answer. This time the solution is complete with AES CIPHER and it should be easy to plug into your code.
Suggestion: the listener java code can be easily modified to start a H2 tcp server as well, useful to enable the automatic mixed mode (embedded+tcp).
Add 3 lines to the file web.xml:
<listener>
<listener-class>com.mine.MyServletContextListener</listener-class>
</listener>
File MyServletContextListener.java:
package com.mine;
import javax.servlet.*;
import java.sql.*;
public class MyServletContextListener implements ServletContextListener {
Connection conn;
public void contextInitialized(ServletContextEvent sce) {
try {
Class.forName("org.h2.Driver");
conn = DriverManager.getConnection( "jdbc:h2:" + sce.getServletContext().getRealPath("/") + "/WEB-INF/data/myDB;CIPHER=AES", "sa", "aespassword dbpassword");
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM INFORMATION_SCHEMA.TABLES");
while (rs.next()) {
}
rs.close();
stmt.close();
} catch(SQLException e) {
} catch(ClassNotFoundException e) {
} finally {
}
}
public void contextDestroyed(ServletContextEvent sce) {
try {
conn.close();
} catch(SQLException e) {
} finally {
}
}
}
How do I set batch size in spring JDBC batch update to improve performance?
Listed below is my code snippet.
public void insertListOfPojos(final List<Student> myPojoList) {
String sql = "INSERT INTO " + "Student " + "(age,name) " + "VALUES "
+ "(?,?)";
try {
jdbcTemplateObject.batchUpdate(sql,
new BatchPreparedStatementSetter() {
#Override
public void setValues(PreparedStatement ps, int i)
throws SQLException {
Student myPojo = myPojoList.get(i);
ps.setString(2, myPojo.getName());
ps.setInt(1, myPojo.getAge());
}
#Override
public int getBatchSize() {
return myPojoList.size();
}
});
} catch (Exception e) {
System.out.println("Exception");
}
}
I read that with Hibernate you can provide your batch size in the
configuration xml.
For example,
<property name="hibernate.jdbc.batch_size" value="100"/>.
Is there something similar in Spring's jdbc?
There is no option for jdbc that looks like Hibernate; I think you have to get a look to specif RDBMS vendor driver options when preparing connection string.
About your code you have to use
BatchPreparedStatementSetter.getBatchSize()
or
JdbcTemplate.batchUpdate(String sql, final Collection<T> batchArgs, final int batchSize, final ParameterizedPreparedStatementSetter<T> pss)
if you use JDBC directly, you decide yourself how much statements are used in one commit, while using one of the provided JDBCWriters you decide the batch* size with the configured commit-rate
*afaik the actual spring version uses the prepared statement batch methods under the hood, see https://github.com/SpringSource/spring-framework/blob/master/spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java#L549
I am trying to manipulate an Apache Derby DB on NetBeans and I'm having a tough time connecting.
It seems very simple but it just wouldn't connect.
Please help. Thanks in advance!
import java.sql.*;
public class JDBCtutorial {
private static String tableName = "Diseases";
private static Connection conn = null;
private static Statement stmt = null;
public static void createConnection() {
try {
Class.forName("org.apache.derby.jdbc.ClientDriver");
} catch(ClassNotFoundException cnfe) {
System.out.println(cnfe);
}
try {
conn = DriverManager.getConnection("jdbc:derby://localhost:1527/DBName", "user", "password");
} catch (Exception e) {
System.out.println("Cannot connect. . .");
}
}
public static void main(String[] args) {
createConnection();
}
}
You're using the driver for embedded use of Derby (org.apache.derby.jdbc.EmbeddedDriver), yet you try to connect over the network, in which case you should use the network driver, org.apache.derby.jdbc.ClientDriver.
All this is explained in detail in the Derby doc which is quite good.
Also, as probably getConnection is throwing an exception that might give some hints about the cause of the problem, try pinting the stacktrace, it should provide that info:
} catch (Exception e) {
System.out.println("Cannot connect:");
e.printStackTrace();
}
You Just need to add one library file in your project.
Download here
Eclipse : Right Click on project then > Build Path > Configure Build Path > Add External JAR (and select the file you downloaded) > Done
NetBeans : Right Click on project then > Properties > Libraries > ADD JAR/Folder
"and select the file you downloaded " > ok (Run)
Add Permanently : Add the file in c:/program files/java/JRE/lib/ folder
I'm writing a database accessor in Java. The database is in Oracle 11g, of which I am absolutely not familiar, and I have JDK 1.6.
Will ojdbc4.jar do for my program? We're not allowed to connect to the Internet in the office and I can't download ojdbc6.jar, which I've read is more compatible with my setup.
What strings should I put in the Class.forName(String driver) and DriverManager.getConnection(String connectionURL)? I don't know the driver string and the connection URL since they (naturally) look very different from the ones for MS SQL Server.
Oracle bundle the Jar with the Oracle client or server installation and can be found in $ORACLE_HOME/jdbc/lib/ojdbc6.jar. I always use that one.
The Driver classname is oracle.jdbc.OracleDriver and the URL is jdbc:oracle:thin:#//[HOST][:PORT]/SERVICE.
Here's an example (taken from here):
import java.sql.*;
class Conn {
public static void main (String[] args) throws Exception
{
Class.forName ("oracle.jdbc.OracleDriver");
Connection conn = DriverManager.getConnection
("jdbc:oracle:thin:#//localhost:1521/orcl", "scott", "tiger");
// #//machineName:port/SID, userid, password
try {
Statement stmt = conn.createStatement();
try {
ResultSet rset = stmt.executeQuery("select BANNER from SYS.V_$VERSION");
try {
while (rset.next())
System.out.println (rset.getString(1)); // Print col 1
}
finally {
try { rset.close(); } catch (Exception ignore) {}
}
}
finally {
try { stmt.close(); } catch (Exception ignore) {}
}
}
finally {
try { conn.close(); } catch (Exception ignore) {}
}
}
}
The offical JAR file in combination with JDK 1.6 is ojdbc6.jar. But ojdbc4.jar should work for most applications.
Typicall connection strings are:
jdbc:oracle:thin:user/xxxx#server:port:SID
jdbc:oracle:thin:user/xxxx#//server:port/XE
jdbc:oracle:thin:user/xxxx#:SID