从Servlet返回JSON响应到Javascript / JSP页面 [英] Returning JSON response from Servlet to Javascript/JSP page

问题描述

我认为（其实我知道！）我在这里做错了我正在尝试将一些值填充到HashMap中，并将每个hasmap添加到将添加到JSON对象的列表中：

I think (actually I KNOW!) I'm doing something wrong here I am trying to populate some values into HashMap and add each hasmap to a list which will be added to a JSON object:

JSONObject json = new JSONObject();
try
{
    Map address;
    List addresses = new ArrayList();

    int count = 15;

    for (int i=0 ; i<count ; i++)
    {
        address = new HashMap();
        address.put("CustomerName"     , "Decepticons" + i);
        address.put("AccountId"        , "1999" + i);
        address.put("SiteId"           , "1888" + i);
        address.put("Number"            , "7" + i);
        address.put("Building"          , "StarScream Skyscraper" + i);
        address.put("Street"            , "Devestator Avenue" + i);
        address.put("City"              , "Megatron City" + i);
        address.put("ZipCode"          , "ZZ00 XX1" + i);
        address.put("Country"           , "CyberTron" + i);
        addresses.add(address);
    }
    json.put("Addresses", addresses);
}
catch (JSONException jse)
{

}
response.setContentType("application/json");
response.getWriter().write(json.toString());

我的问题是我知道这是返回一个字符串，我似乎无法解析（这是问题）。我的问题是，如何返回实际的JSON编码的字符串（或者甚至应该这样做？）或针对此类问题的最佳攻击方法是什么。我为此使用的JavaScript如下：

My problem is I know this is returning a string, which I cannot seem to parse (which is the problem). My question is how do I return the actual JSON encoded string (or even should I be doing this?) or what is the best method of attack for this type of problem. The JavaScript I am using for this is below:

function getReadyStateHandler(req)
{
    // Return an anonymous function that listens to the
    // XMLHttpRequest instance
    return function ()
    {
        // If the request's status is "complete"
        if (req.readyState == 4)
        {
            // Check that a successful server response was received
            if (req.status == 200)
            {
                msgBox("JSON Response recieved...");
                populateDatagrid(req.responseText.toJSON());
            }
            else
            {
                // An HTTP problem has occurred
                alert("HTTP error: " + req.status);
            }
        }
    }
}

JSON响应恢复正常，但它是一个字符串。任何意见是极大的赞赏。我也开放使用谷歌Gson，但没有太多的知识。

Note the JSON Response comes back fine, but its a string. Any advice is greatly appreciated. I am also opening to using googles Gson, but don't have too much knowledge on that.

推荐答案

得到它的工作！我应该一直在构建 JSONArray 的 JSONObject s，然后将该数组添加到最终的Addresses的JSONObject 。注意以下几点：

Got it working! I should have been building a JSONArray of JSONObjects and then add the array to a final "Addresses" JSONObject. Observe the following:

JSONObject json      = new JSONObject();
JSONArray  addresses = new JSONArray();
JSONObject address;
try
{
   int count = 15;

   for (int i=0 ; i<count ; i++)
   {
       address = new JSONObject();
       address.put("CustomerName"     , "Decepticons" + i);
       address.put("AccountId"        , "1999" + i);
       address.put("SiteId"           , "1888" + i);
       address.put("Number"            , "7" + i);
       address.put("Building"          , "StarScream Skyscraper" + i);
       address.put("Street"            , "Devestator Avenue" + i);
       address.put("City"              , "Megatron City" + i);
       address.put("ZipCode"          , "ZZ00 XX1" + i);
       address.put("Country"           , "CyberTron" + i);
       addresses.add(address);
   }
   json.put("Addresses", addresses);
}
catch (JSONException jse)
{ 

}
response.setContentType("application/json");
response.getWriter().write(json.toString());

这个工作并返回了有效和可分析的JSON。希望这可以帮助未来的其他人。感谢您的帮助Marcel

This worked and returned valid and parse-able JSON. Hopefully this helps someone else in the future. Thanks for your help Marcel

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