Handler实现轮播

首先写入网络权限
导入imagerlouder的jar包
布局
activity的布局

   <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        >

        <android.support.v4.view.ViewPager
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:id="@+id/vp"
            ></android.support.v4.view.ViewPager>
        <LinearLayout
            android:id="@+id/linear"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignBottom="@+id/vp"
            ></LinearLayout>
    </RelativeLayout>

drawable文件夹中的布局
point_selected.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"

    android:shape="oval"
    >
    <solid  android:color="#f00"></solid>

</shape>

point_unselected.xml

<shape xmlns:android="http://schemas.android.com/apk/res/android"

    android:shape="oval"
    >
    <solid  android:color="#fff"></solid>

</shape>

Activity主方法里边

package com.example.denmo21;

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

import com.handmark.pulltorefresh.library.PullToRefreshScrollView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private ImageView[] imgarray;

    private PullToRefreshScrollView psv;
    private ViewPager vp;
    private ListView lv;
    private String url = "http://pic8.nipic.com/20100701/5290458_114840036316_2.jpg";
    private String url2 = "http://pic2.nipic.com/20090424/1468853_230119053_2.jpg";
    private String url3 = "http://img3.3lian.com/2013/s1/20/d/57.jpg";
    private String url4 = "http://pic39.nipic.com/20140226/18071023_164300608000_2.jpg";
    private String url5 = "http://a0.att.hudong.com/15/08/300218769736132194086202411_950.jpg";

    private LinearLayout linear;
    private List<String> pagelist;

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            int index = vp.getCurrentItem();
            vp.setCurrentItem(index + 1);
            getinitimg(index + 1);//改变xioayd
            sendEmptyMessageDelayed(1, 2000);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        psv = (PullToRefreshScrollView) findViewById(R.id.psv);
        vp = (ViewPager) findViewById(R.id.vp);
        lv = (ListView) findViewById(R.id.lv);
        linear = (LinearLayout) findViewById(R.id.linear);
        pagelist = new ArrayList<>();
        pagelist.add(url);
        pagelist.add(url2);
        pagelist.add(url3);
        pagelist.add(url4);
        pagelist.add(url5);
        MyPage myPage = new MyPage(this, pagelist);
        vp.setAdapter(myPage);
        vp.setCurrentItem(pagelist.size() * 100);
        imgarray = new ImageView[pagelist.size()];
        handler.sendEmptyMessageDelayed(1, 1000);
        initimg();//初始化小圆点
    }

    public void getinitimg(int index) {
        int selectindex = index % pagelist.size();
        for (int i = 0; i < pagelist.size(); i++) {
            if (i == selectindex) {
                imgarray[i].setImageResource(R.drawable.point_selected);
            } else {
                imgarray[i].setImageResource(R.drawable.point_unselected);

            }
        }
    }

    /**
     * 初始化小圆点
     */
    public void initimg() {

        for (int i = 0; i < pagelist.size(); i++) {
            ImageView img = new ImageView(this);
            img.setScaleType(ImageView.ScaleType.FIT_XY);
            if (i == 0) {
                img.setImageResource(R.drawable.point_selected);
            } else {
                img.setImageResource(R.drawable.point_unselected);
            }
            //设置小圆点的大小
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(20, 20);
            params.setMargins(0, 0, 10, 10);//设置间距
            linear.addView(img, params);
            imgarray[i] = img;
        }
    }

}

适配器
MyPage

package com.example.denmo21;

import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import com.nostra13.universalimageloader.core.ImageLoader;

import java.util.List;

/**
 * Created by zld on 2017/12/21.
 */

public class MyPage extends PagerAdapter {
    private Context context;
    private List<String> pagelist;

    public MyPage(Context context, List<String> pagelist) {
        this.context = context;
        this.pagelist = pagelist;
    }

    @Override
    public int getCount() {
        return Integer.MAX_VALUE;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == object;
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        ImageView img = new ImageView(context);
        img.setScaleType(ImageView.ScaleType.FIT_XY);
        ImageLoader.getInstance().displayImage(pagelist.get(position % pagelist.size()), img);
        container.addView(img);
        return img;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);
    }
}

MyApption

package com.example.denmo21;

import android.app.Application;

import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;

/**
 * Created by zld on 2017/12/21.
 */

public class MyApption extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        ImageLoaderConfiguration configuration = new ImageLoaderConfiguration.Builder(this).build();
        ImageLoader.getInstance().init(configuration);
    }
}