我用JNDI連接數(shù)據(jù)庫總報錯 "javax.naming.NameNotFoundException：Name java:comp is not bound in this Context

出錯地方如：
   Context ctx = new InitialContext();
   ds = (DataSource) ctx.lookup("java:comp/env/jdbc/test");//數(shù)據(jù)庫名test

tomcat的server.xml部分代碼如下：

<Context path="/test" docBase="D:\workspace\test\jsp" debug="0">
          <Resource name="jdbc/test" type="javax.sql.DataSource"/>
          <ResourceParams name="jdbc/test">
           <parameter>
            <name>factory</name>
            <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
           </parameter>
           <parameter>
            <name>username</name>
            <value>root</value>
           </parameter>
           <parameter>
            <name>password</name>
            <value></value>
           </parameter>
           <parameter>
            <name>driverClassName</name>
            <value>com.mysql.jdbc.Driver</value>
           </parameter>
           <parameter>
            <name>url</name>
            <value>jdbc:mysql://localhost:3306/jnditest?user=root</value>
           </parameter>
          </ResourceParams>
          </Context>
另說明：我用的是tomcat5.5,jdk1.5,mysql-4.0.25,并且已經(jīng)把JAR包放到tomcat下了。
 
請問各位朋友這是什么原因??？