javascript - 有序的 JSONObject

Question

我有一个 servlet，它与数据库对话，然后返回一个有序(按时间排序)对象的列表。在 servlet 部分，我有

                //access DB, returns a list of User objects, ordered
        ArrayList  users = MySQLDatabaseManager.selectUsers();
                //construct response
        JSONObject jsonResponse = new JSONObject();
        int key = 0;
        for(User user:users){
            log("Retrieve User " + user.toString());
            JSONObject jsonObj = new JSONObject();
            jsonObj.put("name", user.getName());
            jsonObj.put("time", user.getTime());
            jsonResponse.put(key, jsonObj);
            key++;
        }
                //write out
        out.print(jsonResponse);

从日志中我可以看到数据库以正确的顺序返回了用户对象。

在前端，我有

success: function(jsonObj){
            var json = JSON.parse(jsonObj);
            var id = 0;
            $.each(json,function(i,item) {              
                var time = item.time;               
                var name = item.name;               
                id++;
                $("table#usertable tr:last").after('<tr><td>' + id + '</td><td width="20%">' + time + 
                        '</td><td>' + name + 
                        '</td></tr>');
            });

        },

但是顺序变了。

我只在返回的列表很大(超过 130 个用户)时才注意到这一点。

我尝试使用 Firebug 进行调试，Firebug 中的“响应选项卡”显示列表的顺序与 servlet 中的日志不同。

我做错了什么吗？

编辑:例子

{"0":{"time":"2011-07-18 18:14:28","email":"xxx@gmail.com","origin":"origin-xxx","source":"xxx","target":"xxx","url":"xxx"},
"1":{"time":"2011-07-18 18:29:16","email":"xxx@gmail.com","origin":"xxx","source":"xxx","target":"xxx","url":"xxx"},
"2":

,...,
"143":{"time":"2011-08-09 09:57:27","email":"xxx@gmail.com","origin":"xxx","source":"xxx","target":"xxx","url":"xxx"}

,...,
"134":{"time":"2011-08-05 06:02:57","email":"xxx@gmail.com","origin":"xxx","source":"xxx","target":"xxx","url":"xxx"}}

Answer 1

由于 JSON 对象本身没有顺序，您应该在 JSON 对象中使用数组来确保顺序。作为示例(基于您的代码):

 jsonObj = 
          { items:
            [ { name: "Stack", time: "..." },
              { name: "Overflow", time: "..." },
              { name: "Rocks", time: "..." },
              ... ] };

此结构将确保您的对象以正确的顺序插入。

根据上面的 JSON，您可以将对象放入一个数组中，然后对该数组进行排序。

 var myArray = [];
 var resultArray;

 for (var j in jsonObj) {
   myArray.push(j);
 }

 myArray = $.sort(myArray, function(a, b) { return parseInt(a) > parseInt(b); });

 for (var i = 0; i < myArray.length; i++) {
   resultArray.push(jsonObj[myArray[i]]);
 }

 //resultArray is now the elements in your jsonObj, properly sorted;

但也许这比您正在寻找的更复杂..