AsyncTask加载网络数据

一 ，添加权限

   

<uses-permission android:name="android.permission.INTERNET"/>

二 ， 网络判断工具类

public class HttpUtils {

        //get请求获取网络数据
        public  static String getData(String utl) {
            try {
                URL url = new URL(utl);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setConnectTimeout(1024 * 8);
                connection.setReadTimeout(1024 * 8);
                connection.setRequestMethod("GET");
                int responseCode = connection.getResponseCode();
                if (responseCode == 200) {
                    InputStream inputStream = connection.getInputStream();
                    int len = 0;
                    byte[] buf = new byte[1024 * 8];
                    ByteArrayOutputStream baos = new ByteArrayOutputStream();
                    while ((len = inputStream.read(buf)) != -1) {
                        baos.write(buf, 0, len);
                    }
                    baos.close();
                    return baos.toString();
                } else {
                    Log.e("TAG", "onCreate: Error" + responseCode);
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }
    }

三 ，图片加载工具类

public class Imageloderutils {
    public static void setImageView(String url, Context context, ImageView imageView) {


        //初始化
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(context).build();
        //创建Imageloader 对象
        ImageLoader imageLoader = ImageLoader.getInstance();
        //设置初始化
        imageLoader.init(config);


        DisplayImageOptions options = new DisplayImageOptions.Builder()
                .showImageOnLoading(R.mipmap.ic_launcher) //设置图片在下载期间显示的图片
                .showImageForEmptyUri(R.mipmap.ic_launcher)//设置图片Uri为空或是错误的时候显示的图片
                .showImageOnFail(R.mipmap.ic_launcher)  //设置图片加载/解码过程中错误时候显示的图片
                .cacheInMemory(true)//设置下载的图片是否缓存在内存中
                .cacheOnDisk(true)//设置下载的图片是否缓存在SD卡中
                .imageScaleType(ImageScaleType.IN_SAMPLE_INT)//设置图片以如何的编码方式显示
                .bitmapConfig(Bitmap.Config.RGB_565)//设置图片的解码类型
                .build();//构建完成

        imageLoader.displayImage(url, imageView, options);


    }
}

四 ，解析字符串的bean类

public class MyBean {
    public String reason;
    public ResultBean result;
    public int error_code;

    public static class ResultBean {

        public String stat;
        public List<DataBean> data;

        public static class DataBean {


            public String uniquekey;
            public String title;
            public String date;
            public String category;
            public String author_name;
            public String url;
            public String thumbnail_pic_s;
            public String thumbnail_pic_s02;
            public String thumbnail_pic_s03;
        }
    }
}

五，适配器，用来显示数据

public class MyAdapter extends BaseAdapter {
    private Context context;
    private List<MyBean.ResultBean.DataBean> list;

    public MyAdapter(Context context, List<MyBean.ResultBean.DataBean> list) {
        this.context = context;
        this.list = list;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int i) {
        return null;
    }

    @Override
    public long getItemId(int i) {
        return 0;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder holder;
        if(view == null){
            holder = new ViewHolder();
            view = View.inflate(context,R.layout.item,null);
            holder.iv = view.findViewById(R.id.iv);
            holder.tv = view.findViewById(R.id.tv);
            view.setTag(holder);

        }else{
            holder = (ViewHolder) view.getTag();
        }

        //赋值
        holder.tv.setText(list.get(i).title);
        Imageloderutils.setImageView(list.get(i).thumbnail_pic_s,context,holder.iv);

        return view;
    }
    class ViewHolder{
        TextView tv;
        ImageView iv;
    }
}

六,布局MainActivity.xml(我这里使用的是XListView,实现上拉刷新刷新，下拉加载，需要添加依赖库或是依赖包，你可以使用listview显示数据)

<com.bawei.xlistviewlibrary.XListView
    android:id="@+id/xlistview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    />

七，布局每一条数据的显示情况

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">
    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="显示数据" />

    <ImageView
        android:id="@+id/iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
       />
</LinearLayout>

八，操作数据，MainActivity中

public class MainActivity extends AppCompatActivity implements XListView.IXListViewListener {
    private List<MyBean.ResultBean.DataBean> list ;

    private XListView lv;
    private MyAdapter myAdapter;
    private String utl="http://v.juhe.cn/toutiao/index?type=toutiao&key=d4c18a18c3391f90dc971633f6e6f445";

    Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            //刷新listView
            myAdapter.notifyDataSetChanged();
            //隐藏头和尾
            closeXlistView();
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        list = new ArrayList<MyBean.ResultBean.DataBean>();
        initView();
        new MyAsyncTask().execute(utl);
        //开启下拉刷新
        lv.setPullRefreshEnable(true);
        //开启加载更多可用
        lv.setPullLoadEnable(true);
        lv.setXListViewListener(this);
    }
    //此方法在主线程中调用即可,放到点击事件,或者onCreate方法都可以,参数就是要请求的网址


    //自定义的AsyncTask
    private class MyAsyncTask extends AsyncTask<String, Integer, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        //这个方法运行在子线程,我们可以做一个耗时操作
        @Override
        protected String doInBackground(String... strings) {
            //网络请求的操作,注意用return返回获取到的字符串,加网络权限
            String data = HttpUtils.getData(strings[0]);
            Gson gson = new Gson();
            MyBean myBean = gson.fromJson(data,MyBean.class);

            list.addAll(myBean.result.data) ;

            return null;
        }

        //运行在主线程,这个方法在doInBackground执行之后执行.我们一般做从网络拿到数据,使用的数据的操作
        @Override
        protected void onPostExecute(String s) {
            //拿到处理后的数据,更新UI
            myAdapter = new MyAdapter(MainActivity.this,list);
            lv.setAdapter(myAdapter);
            super.onPostExecute(s);
        }
    }


    private void initView() {

        lv = (XListView) findViewById(R.id.xlistview);
    }



    @Override
    public void onRefresh() {
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {

                list.add(0,list.get(5));
                handler.sendEmptyMessage(0);
            }
        },2000);
    }

    @Override
    public void onLoadMore() {
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                for(int x=0; x<10; x++){
                    list.add(list.get(x));
                }
                handler.sendEmptyMessage(0);
            }
        },2000);
    }
    private void closeXlistView() {
        //停止加载更多
        lv.stopLoadMore();
        //停止刷新
        lv.stopRefresh();
        //更新时间
        lv.setRefreshTime("一分钟前");
    }
}

案例效果图：