This is an step by step guide to create Database Pooling for java web based application which is recommended for preformance.
Ingredients:
Container used : Tomcat v7
Databse used : MS SQL Server 2008
IDE used : Eclipse
Get latest Microsoft JDBC Driver 4.0 for SQL server from here
Use sqljdbc4.jar for Java6.
Step 1:
Create dynamic web project in Eclipse say DBPoolingSample.
Step 2:
Create XML file in WebContentMETA-INFcontext.xml
<?xml version="1.0" encoding="UTF-8"?> <Context> <!-- Specify a JDBC datasource --> <Resource name="jdbc/testdb" auth="Container" type="javax.sql.DataSource" username="<username>" password="<password>" driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver" url="jdbc:sqlserver://localhost:1434;DatabaseName=connectpool_db" maxActive="10" maxIdle="4" /> </Context>
Note: Check IP for SQL server instance.
Note: Change username password.
Step 3:
Create a java class to retrieve Connection object.
package db.;
package db;
import java.sql.Connection;
import java.sql.SQLException;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
/**
*
* @author abhishek.anne
*
*/
public class DBConnect {
private DataSource dataSource;
private Connection connection;
private static DBConnect moDbConnect;
private DBConnect() {
try {
// Get DataSource
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:/comp/env");
dataSource = (DataSource) envContext.lookup("jdbc/testdb");
} catch (NamingException e) {
e.printStackTrace();
}
}
public static Connection getConnection() throws NullPointerException{
if (moDbConnect != null) {
try {
moDbConnect.connection = moDbConnect.dataSource.getConnection();
} catch (SQLException sqle) {
sqle.printStackTrace();
}
return moDbConnect.connection;
} else {
moDbConnect = new DBConnect();
try {
moDbConnect.connection = moDbConnect.dataSource.getConnection();
} catch (SQLException sqle) {
sqle.printStackTrace();
}
return moDbConnect.connection;
}
}
}
Step 4:
Create anyservlet to use connection obejct to perform db operation.
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import db.DBConnect;
public class DBServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
Connection connection=null;
Statement statement=null;
ResultSet resultSet = null;
try {
connection = DBConnect.getConnection();
statement = connection.createStatement();
String query = "SELECT * FROM [coonectpool_db].[dbo].[user]";
resultSet = statement.executeQuery(query);
PrintWriter out=resp.getWriter();
while (resultSet.next()) {
out.println(resultSet.getInt(1) + resultSet.getString(2));
}
} catch (SQLException e) {
e.printStackTrace();
}finally {
try {
if (null != resultSet)
resultSet.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (null != statement)
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if (null != connection)
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
Step 5:
Sample web.xml file
<?xml version="1.0" encoding="UTF-8"?> <web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>TomcatConnectionPooling</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>TestServlet</servlet-name> <servlet-class> servlet.DBServlet </servlet-class> </servlet> <servlet-mapping> <servlet-name>TestServlet</servlet-name> <url-pattern>/servlet/test</url-pattern> </servlet-mapping> </web-app>
Step 6:
Deploy Application and browse
http://localhost:<port>/DBPoolingSample/servlet/test
By making driver change you can connect to respective Database server
like:
MY SQL:com.mysql.jdbc.Driver
Oracle :oracle.jdbc.driver.OracleDriver
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