Android开发之从网络URL上下载JSON数据

网络下载拉取数据中，json数据是一种格式化的xml数据，非常轻量方便，效率高，体验好等优点，下面就android中如何从给定的url下载json数据给予解析：

主要使用http请求方法，并用到HttpGet和HttpResponse等对象来获取数据。直接上实例代码吧：、

（1）从网络URL上读取json字符串的实现

public String readJSONFeed(String url){
        StringBuilder stringBuilder = new StringBuilder();
        HttpClient client = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(url);
        HttpResponse response;
        try {
            response = client.execute(httpGet);
            StatusLine statusLine = response.getStatusLine();
            int statusCode = statusLine.getStatusCode();
            if(statusCode == 200){
                HttpEntity entity = response.getEntity();
                InputStream content = entity.getContent();
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(content));
                String line ;
                while((line = reader.readLine())!=null){
                    stringBuilder.append(line);
                }
            }else{
                Log.e("JSON", "Failed to download file");
            }
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return stringBuilder.toString();
    }

（2）异步方法拉取网络上的数据的实现：

private class ReadJSONFeedTask extends AsyncTask<String, Void, String>{

        StringBuilder stringBuilder  = new StringBuilder();
        @Override
        protected String doInBackground(String... urls) {
            // TODO Auto-generated method stub
            return readJSONFeed(urls[0]);
        }

        @Override
        protected void onPostExecute(String result) {
            // TODO Auto-generated method stub
            String strItem;
            try {
                JSONArray jsonArray = new JSONArray(result);
                for(int i = 0;i<jsonArray.length();i++){
                    JSONObject jsonObject = jsonArray.getJSONObject(i);
                    strItem= jsonObject.getString("appeId")+
                            " - "+jsonObject.getString("inputTime") +"\n";
                    stringBuilder.append(strItem);
                }
                ((TextView)findViewById(R.id.tvJson)).setText(stringBuilder.toString());
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            
        }
        
    }

（3）最后如何启一个异步下载任务呢？其实就是new一个上面的异步类对象并执行即可

new ReadJSONFeedTask().execute(jsonUrl);

到此为止，从网络URL上下载json数据已经成功完成了。最后下载后的数据显示结果如下：