tomcat 连接多个数据源

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：