SYS异步请求网络数据

  public String urlString = "http://api.expoon.com/AppNews/getNewsList/type/1/p/1";
    String urlBitmap = "https://img-my.youkuaiyun.com/uploads/201407/26/1406383265_8550.jpg";
    private ListView listView;
    ArrayList<Product.DataBean> dataBeanList = new ArrayList();// 集合为空；
    private MAdapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = (ListView) findViewById(R.id.lv);
        //直接调用asyncTask类请求网络,把url传进去
        mAdapter = new MAdapter();
        listView.setAdapter(mAdapter);
        /**
         * 这行代码要在主线程调用;,execute里面的参数是接口地址；让async请求网络,并更新UI;
         * 1 不用开子线程,
         * 2 不用写handler;
         * 因为asynctask底层原理就是用的Thread+handler帮我们把事情做了;
         *
         */

        new MAsyncTask().execute(urlString);

    }

    /**
     * 处理异步任务
     * 泛型 1---传递过来的参数类型
     *      2--进度
     *      3--返回值得类型
     */
    class MAsyncTask extends AsyncTask<String,Void,String>{

        /**
         * 这个方法运行在子线程;让他去请求网络,
         * @param strings  可变参数;
         * @return
         */
        @Override
        protected String doInBackground(String... strings) {
            String stringUrl = strings[0];
            String netJson = NetUtil.getNetJson(stringUrl);
            return netJson;
        }

        /**
         *onPostExecute这个方法是运行在主线程,可以更新UI;
         *
         * @param netJson 这个参数s  就是doInBackground返回值;
         */
        @Override
        protected void onPostExecute(String netJson) {
            super.onPostExecute(netJson);
            Gson gson = new Gson();
            Product product = gson.fromJson(netJson, Product.class);
            dataBeanList.addAll(product.getData());
            mAdapter.notifyDataSetChanged();//可以直接更新适配器,因为这个方法是在主线程

        }
    }

    private class MAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            Log.e("wzq", "getCount:" + dataBeanList.size());
            return dataBeanList.size();
        }

        @Override
        public Object getItem(int i) {
            return dataBeanList.get(i);
        }

        @Override
        public long getItemId(int i) {
            return i;
        }

        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            View view1 = View.inflate(MainActivity.this, R.layout.item02, null);
            TextView tv_name = view1.findViewById(R.id.tv_name);
            ImageView iv = view1.findViewById(R.id.iv);
            tv_name.setText(dataBeanList.get(i).getNews_summary());

            new MBitmapAsyncTask(iv).execute(dataBeanList.get(i).getPic_url());

            Log.e("wzq", "getCount:" + "执行getview");
            return view1;
        }
    }

    /**
     * 用asyncTask请求服务器图片
     */
    private class MBitmapAsyncTask extends  AsyncTask<String,Void,Bitmap>{

        ImageView iv;

        public MBitmapAsyncTask(ImageView iv) {
            this.iv = iv;
        }

        @Override
        protected Bitmap doInBackground(String... strings) {
            Bitmap mbitmap = NetUtil.getNetBitmap(strings[0]);

            return mbitmap;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            //更新ui,因为这是主线程
            iv.setImageBitmap(bitmap);

        }

封装的netutil类{

  private static String tag = "getNetJson";

    public static String getNetJson(String urlString) {
        try {
            //url对象封装接口字符串
            URL url = new URL(urlString);
            //用url打开连接, 返回值我们用HttpURLConnection
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setConnectTimeout(8000);//设置链接超时时间
            int responseCode = urlConnection.getResponseCode(); //获取状态码
            if (responseCode == 200) {
                InputStream inputStream = urlConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                //可拼接的字符串
                StringBuilder stringBuilder = new StringBuilder();
                String temp = "";
                while ((temp = bufferedReader.readLine()) != null) {
                    stringBuilder.append(temp);

                }
                String jsonString = stringBuilder.toString();
                return jsonString;
            } else {
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
            Log.e(tag, "getNetJson: " + e.toString());
        } catch (IOException e) {
            e.printStackTrace();
            Log.e(tag, "getNetJson: " + e.toString());
        }

        return "";
    }

    /**
     * 获取网络图片
     *
     * @param urlString
     * @return
     */
    public static Bitmap getNetBitmap(String urlString) {
        try {
            URL url = new URL(urlString);
            HttpURLConnection httpurlConnection = (HttpURLConnection) url.openConnection();
            httpurlConnection.setConnectTimeout(8000);//设置链接超时时间
            int responseCode = httpurlConnection.getResponseCode();

            if (responseCode == 200) {
                InputStream inputStream = httpurlConnection.getInputStream();
                //BitmapFactory:  android提供好的加工图片的工具类,
                Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
                return bitmap;
            } else {
                //do nothing
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
            Log.e(tag, "getNetBitmap: " + e.toString());
        } catch (IOException e) {
            e.printStackTrace();
            Log.e(tag, "getNetBitmap: " + e.toString());
        }
        return null;
    }

}
    }