Tomcat配置多数据源

测试的tomcat为apache-tomcat-6.0.18 ，数据库为mysql和oracle。

配置步骤如下：

1、把数据库的JDBC驱动放入D:\apache-tomcat-6.0.18\lib目录下

2、在D:\apache-tomcat-6.0.18\conf\web.xml文件中，将下面代码加入到web.xml中：

    <resource-ref>
        <description>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>
    <resource-ref>
        <description>DB Connection</description>
        <res-ref-name>jdbc/oracle</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
    </resource-ref>

3、在D:\apache-tomcat-6.0.18\conf\server.xml文件中,在Host节点下添加Context子节点，配置如下 

        <Context path="/ljqtest" docBase="ljqtest" debug="5" reloadable="true" crossContext="true">
        <Resource name="jdbc/mysql" 
            type="javax.sql.DataSource"
            username="root"
            password="mysql"
            driverClassName="org.gjt.mm.mysql.Driver"
            url="jdbc:mysql://localhost:3306/shop"
            maxIdle="2"
            maxWait="50"
            maxActive="4">
            <parameter>
                <name>removeAbandoned</name>
                <value>true</value>
            </parameter>
        </Resource>
        <Resource name="jdbc/oracle" 
            type="javax.sql.DataSource"
            username="test"
            password="test"
            driverClassName="oracle.jdbc.driver.OracleDriver"
            url="jdbc:oracle:thin:@localhost:1521:ORCL"
            maxIdle="2"
            maxWait="50"
            maxActive="4">
            <parameter>
                <name>removeAbandoned</name>
                <value>true</value>
            </parameter>
        </Resource>
        </Context>
      </Host>

或者

        <Context path="/uimcardprj" docBase="uimcardprj" debug="5" reloadable="true" crossContext="true">      
             <Resource name="jdbc/ycxkDB"             
                 type="javax.sql.DataSource"            
                 username="ycxk"            
                 password="xmzh"            
                 driverClassName="oracle.jdbc.driver.OracleDriver"            
                 url="jdbc:oracle:thin:@(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = 134.128.48.250)(PORT = 1521))(CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME = orcl)))"            
                 maxIdle="2"            
                 maxWait="50"            
                 maxActive="4">               
             </Resource>        
          </Context>
      </Host>

注意：path为D:\apache-tomcat-6.0.18\webapps目录下的工程名称 
4、把web工程项目部署在D:\apache-tomcat-6.0.18\webapps目录下 

MysqlConn类：获取Mysql数据源

package com.ljq.test;

import java.sql.Connection;
import java.sql.SQLException;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;

public final class MysqlConn {
    // 懒汉式单例(使用时才new)
    private static MysqlConn instance = null;

    MysqlConn() {
    }

    // 延迟初始化(用到的时候才加载)(推荐)
    // public static synchronized JdbcConn
    // getInstance(){}->这样不好，因为每调用一次就同步，效率非常低
    public static MysqlConn getInstance() {
        if (instance == null) {
            synchronized (MysqlConn.class) {// 可能会产生并发的问题，我们对他进行同步
                if (instance == null) {
                    instance = new MysqlConn();
                }
            }
        }
        return instance;
    }
    
    private DataSource getDataSource() {
        DataSource ds = null;
        try {
            Context ctx = new InitialContext();
            ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
        } catch (Exception e) {
            System.out.println("数据源获取失败");
            e.printStackTrace();
        }
        return ds;
    }

    public Connection getConn() {
        Connection conn = null;
        try {
            conn = getDataSource().getConnection();
        } catch (SQLException e) {
            System.out.println("数据库连接失败");
            e.printStackTrace();
        }
        return conn;
    }

}

OraclelConn类：获取Oracle数据源

package com.ljq.test;

import java.sql.Connection;
import java.sql.SQLException;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;

public final class OracleConn {
    // 懒汉式单例(使用时才new)
    private static OracleConn instance = null;

    OracleConn() {
    }

    // 延迟初始化(用到的时候才加载)(推荐)
    // public static synchronized JdbcConn
    // getInstance(){}->这样不好，因为每调用一次就同步，效率非常低
    public static OracleConn getInstance() {
        if (instance == null) {
            synchronized (OracleConn.class) {// 可能会产生并发的问题，我们对他进行同步
                if (instance == null) {
                    instance = new OracleConn();
                }
            }
        }
        return instance;
    }
    
    private DataSource getDataSource() {
        DataSource ds = null;
        try {
            Context ctx = new InitialContext();
            ds = (DataSource) ctx.lookup("java:comp/env/jdbc/mysql");
        } catch (Exception e) {
            System.out.println("数据源获取失败");
            e.printStackTrace();
        }
        return ds;
    }

    public Connection getConn() {
        Connection conn = null;
        try {
            conn = getDataSource().getConnection();
        } catch (SQLException e) {
            System.out.println("数据库连接失败");
            e.printStackTrace();
        }
        return conn;
    }

}

页面index.jsp:打印数据库连接对象

  <body>
    mysql连接对象为：<%Connection conn=MysqlConn.getInstance().getConn();%><%=conn %><%conn.close();%><br/>
    oracle连接对象为：<%Connection conn2=MysqlConn.getInstance().getConn();%><%=conn2 %><%conn2.close();%><br/>
  </body>

5、启动tomcat，在浏览器中输入：http://localhost:8083/ljqtest/，输出如下：