ListView多条目展示 请求网络数据 和图片

public class MainActivity extends AppCompatActivity {

    private ListView lv;
    private List<Da.DataBean> list;


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

        // 找控件
        lv = (ListView) findViewById(R.id.lv);
        list = new ArrayList<Da.DataBean>();
        // 初始化数据
        initData();

    }

    private void initData() {

        new AsyncTask<String,Integer,String>(){
            @Override
            protected void onPostExecute(String s) {
                // 设置适配器
                MyAdapter adapter = new MyAdapter();
                lv.setAdapter(adapter);

                super.onPostExecute(s);
            }

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

                getData();

                // ImageLoader
                ImageLoaderConfiguration configuration = ImageLoaderConfiguration.createDefault(MainActivity.this);
                ImageLoader.getInstance().init(configuration);

                return null;

            }
        }.execute();

    }

    private void getData() {

        try {
            // 请求网络数据
            URL url = new URL("http://");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            int code = conn.getResponseCode();
            if(code == 200){

                Gson gson = new Gson();
                Da da = gson.fromJson(new InputStreamReader(conn.getInputStream(),"GBK"),Da.class);
                list = da.getData();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    // 优化适配器
    class MyAdapter extends BaseAdapter{

        public static final int TYPE_ONE = 1;
        public static final int TYPE_TWO = 2;
        public static final int TYPE_THREE = 3;


        // 在使用多条目加载的时候    返回当前position对应的类型
        // ************必须满足的条件   getItemViewType的返回值  必须要小于getViewTypeCount的返回值
        @Override
        public int getItemViewType(int position) {

            if(list.get(position).getType() == 10001){
                return TYPE_ONE;
            }else if(list.get(position).getType() == 10002){
                return TYPE_TWO;
            }else{
                return  TYPE_THREE;
            }
        }

        // 使用多条目加载时   一共有几种类型
        // 从写该方法后，listview控件会知道  当前的布局样式不止一种
        // 所以 当ListView发现convertview在复用时  类型匹配不上时  会重新让convertView加载一遍布局
        @Override
        public int getViewTypeCount() {
            return 5;
        }

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

        @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 view, ViewGroup viewGroup) {

            ViewHolder1 holder1 = null;
            ViewHolder2 holder2 = null;
            ViewHolder3 holder3 = null;

            int type = getItemViewType(position);

            if(view == null){

                if(type == TYPE_ONE) {
                    view = View.inflate(MainActivity.this, R.layout.item1, null);
                    holder1 = new ViewHolder1();
                    holder1.news_id1 = view.findViewById(R.id.tv1_id);
                    holder1.news_title1 = view.findViewById(R.id.tv1_title);
                    holder1.news_summary1 = view.findViewById(R.id.tv1_summary);
                    holder1.pic_url1 = view.findViewById(R.id.iv1);

                    view.setTag(holder1);
                }else if(type == TYPE_TWO){
                    view = View.inflate(MainActivity.this, R.layout.item2, null);
                    holder2 = new ViewHolder2();
                    holder2.news_id2 = view.findViewById(R.id.tv2_id);
                    holder2.news_title2 = view.findViewById(R.id.tv2_title);
                    holder2.news_summary2 = view.findViewById(R.id.tv2_summary);
                    holder2.pic_url2 = view.findViewById(R.id.iv2);
                    view.setTag(holder2);
                }else{
                    view = View.inflate(MainActivity.this, R.layout.item3, null);
                    holder3 = new ViewHolder3();
                    holder3.news_id3 = view.findViewById(R.id.tv3_id);
                    holder3.news_title3 = view.findViewById(R.id.tv3_title);
                    holder3.news_summary3 = view.findViewById(R.id.tv3_summary);
                    holder3.pic_url3 = view.findViewById(R.id.iv3);
                    view.setTag(holder3);
                }
            }else{
                if(type == TYPE_ONE){
                    holder1 = (ViewHolder1) view.getTag();
                }else if(type == TYPE_TWO){
                    holder2 = (ViewHolder2) view.getTag();
                }else{
                    holder3 = (ViewHolder3) view.getTag();
                }
            }

            // 根据不同的情况  把进行赋值
            if(type == TYPE_ONE) {
                holder1.news_id1.setText(list.get(position).getNews_id());
                holder1.news_title1.setText(list.get(position).getNews_title());
                holder1.news_summary1.setText(list.get(position).getNews_summary());
                ImageLoader.getInstance().displayImage(list.get(position).getPic_url(),holder1.pic_url1);

            }else if(type == TYPE_TWO){
                holder2.news_id2.setText(list.get(position).getNews_id());
                holder2.news_title2.setText(list.get(position).getNews_title());
                holder2.news_summary2.setText(list.get(position).getNews_summary());
                ImageLoader.getInstance().displayImage(list.get(position).getPic_url(),holder2.pic_url2);
            }else{
                holder3.news_id3.setText(list.get(position).getNews_id());
                holder3.news_title3.setText(list.get(position).getNews_title());
                holder3.news_summary3.setText(list.get(position).getNews_summary());
                ImageLoader.getInstance().displayImage(list.get(position).getPic_url(),holder3.pic_url3);
            }

            return view;
        }
    }


    public static class ViewHolder1{

        TextView news_id1,news_title1,news_summary1;
        ImageView pic_url1;
    }

    public static class ViewHolder2{

        TextView news_id2,news_title2,news_summary2;
        ImageView pic_url2;
    }

    public static class ViewHolder3{

        TextView news_id3,news_title3,news_summary3;
        ImageView pic_url3;
    }
}