网络获取图片实现无限轮播图

import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.ViewParent;
import android.widget.ImageView;
import android.widget.LinearLayout;

import com.google.gson.Gson;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity {

    private ViewParent viewParent;



    private ViewPager viewPager;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == 0){
                int currentItem = viewPager.getCurrentItem();
                viewPager.setCurrentItem(currentItem+1);

                handler.sendEmptyMessageDelayed(0,2000);
            }
        }
    };

    private LinearLayout linearLayout;
    private List<ImageView> images;
    private List<Bean.NewslistBean> list;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewPager = (ViewPager) findViewById(R.id.view_pager);
        linearLayout = (LinearLayout) findViewById(R.id.linear_layout);

        toYiBu();

    }

    private void toYiBu() {
        AsyncTask<Void, Void, String> asyncTask = new AsyncTask<Void, Void, String>() {

            @Override
            protected String doInBackground(Void... voids) {
                try {
                    URL url = new URL("https://api.tianapi.com/wxnew/?key=8d6e3228d25298f13af4fc40ce6c9679&num=6&page=1");
                    HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                    urlConnection.setConnectTimeout(5000);
                    urlConnection.setReadTimeout(5000);
                    int responseCode = urlConnection.getResponseCode();
                    if (responseCode==200){
                        InputStream inputStream = urlConnection.getInputStream();
                        String json = ZhuanHuan(inputStream);
                        return json;
                    }


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

                return null;
            }

            @Override
            protected void onPostExecute(String json) {
                super.onPostExecute(json);
                Gson gson = new Gson();
                Bean bean = gson.fromJson(json, Bean.class);
                list = bean.getNewslist();
                //初始化小圆点
                initDoc();


                //设置适配器
                ImagePager imagePager = new ImagePager(MainActivity.this, list,handler);
                //
                viewPager.setAdapter(imagePager);

                PagerListerne();
                //发送延时消息
                handler.sendEmptyMessageDelayed(0,2000);
            }
        };
    asyncTask.execute();

    }

    private void PagerListerne() {


        //设置ViewPager初始展示的位置
        viewPager.setCurrentItem(list.size()*10000);



        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                //如果选中了这一页,,,当前小圆点红色,,,否则绿色
                for (int i = 0;i<images.size();i++){
                    if (i== position%images.size()){
                        images.get(i).setImageResource(R.drawable.doc_select);
                    }else {
                        images.get(i).setImageResource(R.drawable.doc_select_no);
                    }
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    private String ZhuanHuan(InputStream inputStream) {
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        StringBuilder builder = new StringBuilder();
        String string = null;
        try {
            while ((string=bufferedReader.readLine())!=null){
                builder.append(string);
            }
            return builder.toString();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    private void initDoc() {
        //首先需要一个集合记录这些小圆点的图片,,,,当页面切换的时候,可以从集合中取出imageView进行显示图片的设置
        images = new ArrayList<>();
        linearLayout.removeAllViews();//清空/移除所有的view

        for (int i = 0;i<list.size();i++){
            ImageView imageView = new ImageView(MainActivity.this);

            if (i==0){//显示第一页,,,红的
                imageView.setImageResource(R.drawable.doc_select);
            }else {//绿的
                imageView.setImageResource(R.drawable.doc_select_no);
            }

            //添加到集合
            images.add(imageView);

            //加入到线性布局中显示
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT);

            params.setMargins(5,0,5,0);

            linearLayout.addView(imageView,params);

        }

    }
}