异步加载图片

public class MainActivity extends AppCompatActivity {

    private ListView lv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        lv = (ListView) findViewById(R.id.lv);


        asyncLoadData("http://japi.juhe.cn/health_knowledge/infoList?key=f1f5de8afb705895c13c349b6f8e6513");


    }

    /**
     *加载数据
     * 异步任务实现
     * 请求方式 : GET
     */
    private void asyncLoadData(String path){

        new AsyncTask<String,Void,String>(){


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

            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);

                if(s == null)
                {
                    return;
                }


                //1.解析json时句句

                Gson gson = new Gson();
                HelthInfo helthInfo = gson.fromJson(s,HelthInfo.class);
                List<HelthInfo.ResultBean.DataBean> lists = helthInfo.getResult().getData();
                //2.与适配器绑定
                MyBaseAdapter adapter = new MyBaseAdapter(MainActivity.this,lists);

                //3.映射到ListView
                lv.setAdapter(adapter);
            }

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


                try {
                    String path = params[0];
                    URL url = new URL(path);
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(5000);
                    connection.setReadTimeout(5000);


                    int code = connection.getResponseCode();

                    if(code == 200){
                        //得到服务的数据
                        InputStream is = connection.getInputStream();
                        String result = StreamTools.readFromNetWork(is);
                        return result;
                    }



                } catch (Exception e) {
                    e.printStackTrace();
                }
                return null;
            }
        }.execute(path);
    }

}

public class MyBaseAdapter extends BaseAdapter {

    private List<HelthInfo.ResultBean.DataBean> list;
    private Context context;

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


    @Override
    public int getCount() {
        return list != null ? list.size() : 0;
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {


        if(convertView == null){
            convertView = convertView.inflate(context,R.layout.item,null);
        }

        ImageView ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
        TextView tvContent = (TextView) convertView.findViewById(R.id.tvContent);

        //赋值

        tvContent.setText(list.get(position).getTitle());
        //加载图片
        loadImage(list.get(position).getImg(),ivIcon);


        return convertView;
    }


    /**
     * 加载图片
     * @param path
     * @param ivIcon
     */
    private void loadImage(String path, final ImageView ivIcon){


        new AsyncTask<String,Void,Bitmap>(){


            @Override
            protected void onPostExecute(Bitmap bitmap) {
                super.onPostExecute(bitmap);


                if(bitmap != null){

                    ivIcon.setImageBitmap(bitmap);
                }else{
                    ivIcon.setImageResource(R.mipmap.ic_launcher);
                }


            }

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


                try {
                    String path = params[0];
                    URL url = new URL(path);
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(5000);
                    connection.setReadTimeout(5000);

                    int code = connection.getResponseCode();

                    if(code == 200){

                        InputStream is = connection.getInputStream();
                        Bitmap bitmap = BitmapFactory.decodeStream(is);
                        return bitmap;
                    }


                } catch (Exception e) {
                    e.printStackTrace();
                }


                return null;
            }
        }.execute(path);


    }





}