您是否阅读过http://tomcat.apache.org/tomcat-6.0-doc/jndi-datasource-examples-
howto.html#MySQL_DBCP_Example？它显示了从Web应用程序访问数据库的所有步骤。

如果您需要使用Java代码来访问数据库（比通过JSP更好），则代码应如下所示：

InitialContext initCtx = new InitialContext();
// getting the datasource declared in web.xml
DataSource dataSource = (DataSource) initCtx.lookup("java:comp/env/jdbc/TestDB");

// getting a connection from the dataSOurce/connection pool
Connection c = null;
try {
    c = dataSource.getConnection();
    // use c to get some data
}
finally {
    // always close the connection in a finally block in order to give it back to the pool
    if (c != null) {
        try {
            c.close();
        }
        catch (SQLException e) {
            // not much to do except perhaps log the exception
        }
    }
}

另外，请注意，您还应该关闭try块内使用的结果集和语句。有关更完整的示例，请参见http://tomcat.apache.org/tomcat-6.0-doc/jndi-
datasource-examples-
howto.html#Random_Connection_Closed_Exceptions。