JAVA tomcat 配置jndi而且使用c3p0连接池

配置MYSQL 的JNDI采取的方式时再META-INF文件夹下创建context.xml配置应用的jndi。优点每个应用独立JNDI.

配置文件及其步骤如下：

1、META-INF中创建<context.xml内容如下： 

 <pre name="code" class="html"><?xml version="1.0" encoding="UTF-8"?><Context><Resource        name="jdbc/mysql"        auth="Container"        factory="org.apache.naming.factory.BeanFactory"        type="com.mchange.v2.c3p0.ComboPooledDataSource"        driverClass="com.mysql.jdbc.Driver"        idleConnectionTestPeriod="60"        acquireRetryAttempts="3"        checkoutTimeout="10000"        maxPoolSize="50"        minPoolSize="2"        acquireIncrement="2"        user="root"        password="root"        jdbcUrl="jdbc:mysql://127.0.0.1:3306/ccc?useUnicode=true&characterEncoding=utf-8"/></Context>

2、WEB-INF中web.xml文件中添加引用：

<!--Oracle数据库JNDI数据源引用 --><!--<resource-ref>-->    <!--<description>Oracle DB Connection</description>-->    <!--<res-ref-name>oracleDataSource</res-ref-name>-->    <!--<res-type>javax.sql.DataSource</res-type>-->    <!--<res-auth>Container</res-auth>--><!--</resource-ref>--><!--MySQL数据库JNDI数据源引用 --><resource-ref>    <description>MySQL DB Connection</description>    <res-ref-name>jdbc/mysql</res-ref-name>    <res-type>javax.sql.DataSource</res-type>    <res-auth>Container</res-auth></resource-ref><!--SQLServer数据库JNDI数据源引用 --><!--<resource-ref>-->    <!--<description>SQLServer DB Connection</description>-->    <!--<res-ref-name>sqlserverDataSource</res-ref-name>-->    <!--<res-type>javax.sql.DataSource</res-type>-->    <!--<res-auth>Container</res-auth>--><!--</resource-ref>-->

3、DAO（一个servlet或者专门的数据接入类）中读取配置及其创建connection和DataSource

import sun.jdbc.odbc.ee.ConnectionPool;import javax.naming.*;import javax.sql.DataSource;import java.sql.*;import java.sql.*;import java.sql.SQLException;import java.util.Hashtable;/** * Created by wuxituong on 2016-10-01. */public class SQLDAO {    private static ConnectionPool instace;    private static <pre style="font-family: 宋体; font-size: 9pt; background-color: rgb(255, 255, 255);"><span style="background-color:#e4e4ff;">ComboPooledDataSource</span>

ds; //获得数据源 private static <span style="font-family: Arial, Helvetica, sans-serif;">

ComboPooledDataSource

</span><span style="font-family: Arial, Helvetica, sans-serif;">createDataSource()</span> { if (ds == null) { System.out.println("ds created"); try { Context ct = new InitialContext(); if (ct == null) System.out.println("无配置环境"); Context envContext = (Context) ct.lookup("java:/comp/env"); ds = (<span style="font-family: Arial, Helvetica, sans-serif;">

ComboPooledDataSource

</span><span style="font-family: Arial, Helvetica, sans-serif;">) envContext.lookup("jdbc/mysql"); //根据名称取得数据源</span> } catch (NamingException e) { e.printStackTrace(); } } return ds; } //从连接池中取得连接对象 public static synchronized Connection getConnection() throws SQLException,NamingException{ Connection con=null; try { System.out.print("正准备获取con"); //获取连接 con=(Connection)createDataSource().getConnection(); } catch (Exception e) { e.printStackTrace(); System.out.print("获取连接失败！"); } return con; } //释放连接 public static synchronized void freeConnection(Connection con){ try { con.close(); } catch (SQLException e) { e.printStackTrace(); System.out.println("关闭连接失败！"); } }}

4、使用DAO 记得在使用了con一定要con.close()将连接放回连接池，否则则会造成连接被占用完成，无法再获取con。导致服务器必须重启释放con

 public ResultSet getResultSetData(String sql){        ResultSet rs= null;        try {            Statement sta =  con.createStatement();            rs = sta.executeQuery(sql);            return  rs;        }catch (Exception e){            System.out.println(e.getMessage());            return rs;        }    }    public int exeSql(String sql){        try {            Statement sta =  con.createStatement();            return  sta.executeUpdate(sql);        }catch (Exception e){            System.out.println(e.getMessage());            return -1;        }    }