$.ajax({
        url: "${applicationScope.rootpath}common/getContractPage.html?userConId=${userConId}",
        type: "post",
        dataType:"json",
        data: {},
        success: function (jsonText) {
          if(jsonText){
            var status = jsonText.status;
            var msg = jsonText.msg;
            if(status == '500'){
              //有异常的信息时
            alert(msg);
               
            }else{
              $.each(jsonText,function(i,item){
                var pngPath = item[0];
                var pngName = item[1];
            });
               
            }
          }
        }
      });

{"status":"200","msg":[{"id":"1","name":"n1"},{"id":"2","name":"n2"}]}
{"status":"500","msg":"异常信息"}

List pngFileList = new ArrayList();//某对象集合
if(null != pngFileList && pngFileList.size() > 0) {
JSONArray pngFileArray =JSONArray.fromObject(pngFileList);

}
if(null != pngFileArray){
this.setTextAjax(pngFileArray.toString());
//异常的格式
//this.setTextAjax("{\"status\":\"500\",\"msg\":\""+errormsg+"\"}");//没有记录

/**
* ajax返回html,包括json形式
* 
* @param responseContent
*/
public void setTextAjax(String responseContent) {
try {
HttpServletResponse response = getHttpResponse();
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8");
response.setHeader("Pragma", "No-cache");
response.setHeader("Content-Type", "text/html");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
PrintWriter out = response.getWriter();
out.print(responseContent);
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
// ajaxResponse = new StringBufferInputStream(responseContent);
}

<script src="js/jquery-1.6.4.js" type="text/javascript"></script>
 
<script type="text/javascript">
  $(document).ready(function() {
    $("#Link").click(function() {
    var objson = "[{Title:'Sjr',Content:'Library',summary:'summary'},{Title:'Sjr',Content:'Library',summary:[{sum0:'sum0'},{sum0:'sum1'},{sum0:'sum2'}]},{Title:'Sjr',Content:'Library',summary:[{sum0:'sum0'},{sum0:'sum1'},{sum0:'sum2'}]}]";
      var obj = eval(objson);
      $(obj).each(function(index) {
        var val = obj[index];
        if (typeof (val.summary) == "object") {
          $(val.summary).each(function(ind) {
            alert(val.Title + " " + val.Content + " " + val.summary[ind].sum0);
          });
        } else {
          alert(val.Title + " " + val.Content + " " + val.summary);
        }
      });
    });
  });
</script>

//通过url获取json对象     
     $.post("json/godjson!godlist", function (data){ 
//data.rows返回的是json字符串。需要转换成json对象 
       var json = eval(data.rows) 
//json变量现在就是一个数组对象，直接读取每个数组对象。结合属性进行输出 
       for(var i=0; i<json.length; i++){ 
        alert(json[i].caishen+"--------- " + json[i].xishen); 
       } 
//记得返回的数据类型一定要是json类型 
    }, "json");