更改下拉列表时，Ajax脚本为什么没有触发alert(data);函数？

我想从ajax的success中获得json对象，这就是我到目前为止所做的工作。

我的下拉列表：

<select id="testers_team" class="tester_team">
    <optgroup label="Current Value">
        <option><c:out value="${info.team}"></c:out></option>
    </optgroup>
    <optgroup label="Teams">
        <c:forEach var="team" items="${requestScope.testers}">
            <option value="${team.key}">${team.key}</option>
        </c:forEach>
    </optgroup>
</select>

这是我的Ajax，上面的选择是循环迭代的，所以我必须使用每个循环来知道我正在使用的是哪个下拉列表(只是为了通知用户)。

$('.tester_team').each(function(){
    $(this).change(function() {

          $.ajax({
         url: 'Analysis',
         type: 'POST',
         dataType: 'json',
         data: {team: $(this).val()},
         success: function(data){
             alert(data); // alert not working

         }
          });

    }); 
});

我在servlet上使用gson，下面是代码：

String team = request.getParameter( "team" );
HashMap<String, ArrayList<String>> testerList
              = new UsersDAO().getTestersOfAllTeams();
ArrayList<String> testers = testerList.get( team );

if( testers != null )
{
    response.setContentType( "application/json" );
    response.setCharacterEncoding( "UTF-8" );
    try
    {
        response.getWriter().write( new Gson().toJson( testers ) );
        //this one is printing so that means it actually succeed to parse?
        System.out.println( team );
    }
    catch( IOException e )
    {
       // just want to test out if it really failed
       System.out.println( "failed" ); 
       log.debug( "Unable to get parse request", e );
    }
}

问题在于当我更改下拉列表时，Ajax脚本没有触发alert(data);函数，我的代码有什么问题吗？还是我误用了代码？

The success callback function seems to be failing to parse the JSON result.

Try passing a value to your servlet as a URL query string like http://localhost/project/Analysis?team=some-value-you-know

Then validate the printed JSON using a tool like http://jsonlint.com", fix the JSON you're generating [probably double quotations around the JSON object keys].

Also try using the Developer Tools's JavaScript console in your browser, it will help you with the JavaScript errors.

Hope this helps,
Shareb.

Silly me, alright i found the answer change the code from the servlet:

if( testers != null )
{
    response.setContentType( "application/json" );
    response.setCharacterEncoding( "UTF-8" );
    try
    {
        response.getWriter().write( new Gson().toJson( testers ) );
        //this one is printing so that means it actually succeed to parse?
        System.out.println( team );
    }
    catch( IOException e )
    {
       // just want to test out if it really failed
       System.out.println( "failed" ); 
       log.debug( "Unable to get parse request", e );
    }
}

to

if( testers != null )
{
    response.setContentType( "application/json" );
    response.setCharacterEncoding( "UTF-8" );
    try
    {
        response.getWriter().write( new Gson().toJson( testers ) );
        //this one is printing so that means it actually succeed to parse?
        System.out.println( team );
    }
    catch( IOException e )
    {
       // just want to test out if it really failed
       System.out.println( "failed" ); 
       log.debug( "Unable to get parse request", e );
    }
    return;
}

I just added return;