AsyncTask异步加载和Gson

Android应用数据加载与列表展示

最新推荐文章于 2018-12-29 09:57:50 发布

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最新推荐文章于 2018-12-29 09:57:50 发布

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/wushanmanong/p/5809681.html

本文介绍了一个基于Android的应用程序中如何通过异步任务获取网络数据，并将其解析后显示在一个列表视图中的过程。具体步骤包括：使用HttpClient发起HTTP请求获取JSON数据，通过Gson库解析JSON为自定义对象列表，最后更新UI组件以展示数据。

public class MainActivity extends Activity {
   private List<Goods> goods=new ArrayList<Goods>();

   private ListView lv;
   private SmartImageView smartImageView;

   private MyAdapter adapter;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       lv = (ListView) findViewById(R.id.lv);
       adapter = new MyAdapter(goods, this);
       lv.setAdapter(adapter);
       //获得数据
       huodeshuju();
       lv.setOnItemClickListener(new OnItemClickListener() {

           @Override
           public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                   long arg3) {
               Intent intent=new Intent(MainActivity.this,TwoActivity.class);
               startActivity(intent);


           }
       });
   }
   //获得数据
   private void huodeshuju() {
       //使用异步
       new AsyncTask<String, Void, String>(){

           @Override
           protected String doInBackground(String... params) {

               /*try {
                   URL url=new URL(params[0]);
                   HttpURLConnection urlConnection=(HttpURLConnection) url.openConnection();
                   urlConnection.setConnectTimeout(5000);
                   urlConnection.setReadTimeout(5000);
                   urlConnection.setRequestMethod("GET");
                   urlConnection.connect();
                   int code=urlConnection.getResponseCode();
                   if (code==200) {
                       InputStream inputStream=urlConnection.getInputStream();
                       BufferedReader reader=new BufferedReader(new InputStreamReader(inputStream));
                       String readerline;
                       StringBuffer buffer=new StringBuffer();
                       while ((readerline=reader.readLine())!=null) {
                           buffer.append(readerline);

                       }
                       String str=buffer.toString();
                       return str;
                   }
               } catch (IOException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               }*/




               try {
                   HttpClient httpClient=new DefaultHttpClient();
                   HttpGet httpGet=new HttpGet(params[0]);
                   HttpResponse response = httpClient.execute(httpGet);
                   StatusLine statusLine=response.getStatusLine();
                   int code=statusLine.getStatusCode();
                   if (code==200) {
                       HttpEntity httpEntity=response.getEntity();
                       String str=EntityUtils.toString(httpEntity, "utf-8");
                       return str.toString();
                   }
               } catch (ClientProtocolException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               } catch (IOException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               }


               return null;
           }
           protected void onPostExecute(String result) {
               try {
                   JSONObject obj=new JSONObject(result);
                   JSONObject list=obj.getJSONObject("list");
                   JSONArray articles=list.getJSONArray("articles");
                   Type type=new TypeToken<List<Goods>>(){

                   }.getType();

                   Gson gson=new Gson();
                   List<Goods> goodss=gson.fromJson(articles.toString(), type);
                   for (Goods goods2 : goodss) {

                       String title=goods2.getTitle();
                       String litpic=goods2.getLitpic();
                       String typeid=goods2.getTypeid();
                       Goods goods3=new Goods(title, litpic, typeid);

                       goods.add(goods3);


                   }
                   //Log.i("++++++++", goods.toString());
                   //=======================
                   //必须刷新
                   adapter.notifyDataSetChanged();
                   //======================
               } catch (JSONException e) {
                   // TODO Auto-generated catch block
                   e.printStackTrace();
               }

           };

       }.execute("http://101.200.142.201:8080/tqyb/newsList.json");

   }

   @Override
   public boolean onCreateOptionsMenu(Menu menu) {
       // Inflate the menu; this adds items to the action bar if it is present.
       getMenuInflater().inflate(R.menu.main, menu);
       return true;
   }

}