http://tomcat.apache.org/tomcat-6.0-doc/jndi-datasource-examples-howto.html
前提：开启TOMCAT,MYsql
MySQL DBCP Example
0. Introduction
Versions of MySQL and JDBC drivers that have been reported to work:
MySQL 3.23.47, MySQL 3.23.47 using InnoDB,, MySQL 3.23.58, MySQL 4.0.1alpha
Connector/J 3.0.11-stable (the official JDBC Driver)
mm.mysql 2.0.14 (an old 3rd party JDBC Driver)
Before you proceed, don't forget to copy the JDBC Driver's jar into $CATALINA_HOME/lib.
这句话的意思是说，在开始下面的工作之前必须将JDBC驱动jar包(我用的是mysql-connector-java-5.1.30-bin.jar)，放到G:\apache-tomcat-6.0.39-windows-x86\apache-tomcat-6.0.39/lib目录下，另外我自己昨天捣鼓的时候设置过一些环境变量，不知道会不会有影响，通过下面的测试发现，没有影响。（我的环境变量CATALINA_HOME值设置为G:\apache-tomcat-6.0.39-windows-x86\apache-tomcat-6.0.39）
1. MySQL configuration
Ensure that you follow these instructions as variations can cause problems.
Create a new test user, a new database and a single test table. Your MySQL user must have a password assigned. The driver will fail if you try to connect with an empty password.
mysql> GRANT ALL PRIVILEGES ON *.* TO javauser@localhost
-> IDENTIFIED BY 'javadude' WITH GRANT OPTION;
mysql> create database javatest;
mysql> use javatest;
mysql> create table testdata (
-> id int not null auto_increment primary key,
-> foo varchar(25),
-> bar int);
Note: the above user should be removed once testing is complete!
Next insert some test data into the testdata table.
mysql> insert into testdata values(null, 'hello', 12345);
Query OK, 1 row affected (0.00 sec)
mysql> select * from testdata;
+----+-------+-------+
| ID | FOO | BAR |
+----+-------+-------+
| 1 | hello | 12345 |
+----+-------+-------+
1 row in set (0.00 sec)
mysql>
2. Context configuration
Configure the JNDI DataSource in Tomcat by adding a declaration for your resource to your Context.
For example:
context.xml在G:\apache-tomcat-6.0.39-windows-x86\apache-tomcat-6.0.39\conf目录下（我的笔记本上）
<Context>
<!-- maxActive: Maximum number of database connections in pool. Make sure you
configure your mysqld max_connections large enough to handle
all of your db connections. Set to -1 for no limit.
-->
<!-- maxIdle: Maximum number of idle database connections to retain in pool.
Set to -1 for no limit. See also the DBCP documentation on this
and the minEvictableIdleTimeMillis configuration parameter.
-->
<!-- maxWait: Maximum time to wait for a database connection to become available
in ms, in this example 10 seconds. An Exception is thrown if
this timeout is exceeded. Set to -1 to wait indefinitely.
-->
<!-- username and password: MySQL username and password for database connections -->
<!-- driverClassName: Class name for the old mm.mysql JDBC driver is
org.gjt.mm.mysql.Driver - we recommend using Connector/J though.
Class name for the official MySQL Connector/J driver is com.mysql.jdbc.Driver.
-->
<!-- url: The JDBC connection url for connecting to your MySQL database.
-->
<Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
<!--TestDB是我们自己在webapps下面建立的目录-->
maxActive="100" maxIdle="30" maxWait="10000"
username="javauser" password="javadude" driverClassName="com.mysql.jdbc.Driver"
<!--username="javauser" password="javadude"是我们自己在创建数据库时设置的用户名和密码-->
url="jdbc:mysql://localhost:3306/javatest"/>
<!--连接url="jdbc:mysql://localhost:3306/javatest"是很关键的，javatest是我们建立的数据库名称，3306是连接的端口号，我的是8080，所以修改成8080才能连接成功--> 经过再三测试还是要3306才对
</Context>
3. web.xml configuration
Now create a WEB-INF/web.xml for this test application.
这里原文说的不是很明确，具体操作是在TestDB目录下新建WEB-INF，然后新建web.xml，添加下面的内容。
<web-app 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"
version="2.4">
<description>MySQL Test App</description>
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/TestDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
4. Test code
Now create a simple test.jsp page for use later.
在TestDB目录下新建test.jsp,添加下面的内容
<%@ taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<sql:query var="rs" dataSource="jdbc/TestDB">
select id, foo, bar from testdata
</sql:query>
<html>
<head>
<title>DB Test</title> <!--网页显示的标题-->
</head>
<body>
<h2>Results</h2><!--网页显示的内容-->
<c:forEach var="row" items="${rs.rows}">
Foo ${row.foo}<br/><!--查询数据库内容显示出来-->
Bar ${row.bar}<br/><!--查询数据库内容显示出来-->
</c:forEach>
</body>
</html>
That JSP page makes use of JSTL's SQL and Core taglibs. You can get it from Apache Tomcat Taglibs - Standard Tag Library project — just make sure you get a 1.1.x release. Once you have JSTL, （解压后在\jakarta-taglibs-standard-1.1.1\lib）copy jstl.jar and standard.jar to your web app's WEB-INF/lib directory.
Once deployed, point a browser at http://localhost:8080/DBTest/test.jsp to view the fruits of your hard work.