viewpager无限轮播（从网络上获取图片小圆点）

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import android.content.Context;import android.graphics.Bitmap;import com.nostra13.universalimageloader.cache.disc.impl.UnlimitedDiscCache;import com.nostra13.universalimageloader.cache.disc.naming.Md5FileNameGenerator;import com.nostra13.universalimageloader.core.DisplayImageOptions;import com.nostra13.universalimageloader.core.ImageLoader;import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;import com.nostra13.universalimageloader.core.assist.ImageScaleType;import java.io.File;/** * Created by e531 on 2017/11/13. */public class ImageUtils {    /**     * 对ImageLoader进行初使化     * @param context     */    public static void initImageLoader(Context context){        File cacheFile=context.getExternalCacheDir();//android认为的缓存目录        ImageLoaderConfiguration configuration=new ImageLoaderConfiguration.Builder(context)                .memoryCacheExtraOptions(480, 800)//缓存图片最大的长和宽                .threadPoolSize(2)//线程池的数量                .threadPriority(4)                .memoryCacheSize(2*1024*1024)//设置内存缓存区大小                .diskCacheSize(20*1024*1024)//设置sd卡缓存区大小                .diskCache(new UnlimitedDiscCache(cacheFile))//自定义缓存目录                .writeDebugLogs()//打印日志内容                .diskCacheFileNameGenerator(new Md5FileNameGenerator())//给缓存的文件名进行md5加密处理                .build();        ImageLoader.getInstance().init(configuration);    }    /**     * 得到图片的显示设置类     * @return     */    public static DisplayImageOptions getImageOptions(){        DisplayImageOptions options=new DisplayImageOptions.Builder()                .cacheInMemory(true)//使用内存缓存                .cacheOnDisk(true)//使用磁盘缓存                .bitmapConfig(Bitmap.Config.RGB_565)//设置图片的色彩模式                .imageScaleType(ImageScaleType.EXACTLY)//设置图片的缩放方式                .build();        return options;    }}

创建一个utils，建立一个ImageUtils初始化，

2.public class MyApplication  extends Application{    @Override    public void onCreate() {        super.onCreate();        //进行初使化        ImageUtils.initImageLoader(this);    }}
3.
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;import cuishihao.bwie.com.lianxi2.utils.ImageUtils;/** * Created by e531 on 2017/11/13. */public class MyPagerAdapter  extends PagerAdapter{    private Context context;    //    private int[] imgArray=new int[]{R.mipmap.a0,R.mipmap.a1,R.mipmap.a2};    //用于存放网络图片的url地址    private List<String> imgUrl;    public MyPagerAdapter(Context context,List<String> imgUrl) {        this.context = context;        this.imgUrl=imgUrl;    }    //返回页面的数量    @Override    public int getCount() {        return Integer.MAX_VALUE;    }    @Override    public boolean isViewFromObject(View view, Object object) {        return view==object;    }    //0~getCount返回的值-1    @Override    public Object instantiateItem(ViewGroup container, int position) {        //返回当前显示的视图        ImageView imageView = new ImageView(context);        //图片的绽放方式        imageView.setScaleType(ImageView.ScaleType.FIT_XY);        //0,1,2//        imageView.setImageResource(imgArray[position%imgArray.length]);        //使用ImageLoader下载图片        ImageLoader.getInstance().displayImage(imgUrl.get(position%imgUrl.size()),                imageView, ImageUtils.getImageOptions());        //添加到容器        container.addView(imageView);        return imageView;    }    @Override    public void destroyItem(ViewGroup container, int position, Object object) {        container.removeView((View) object);    }}
4.
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.widget.ImageView;import android.widget.LinearLayout;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity {    private Handler myHandler=new Handler(){        @Override        public void handleMessage(Message msg) {            //获取当前正在显示的页面            int index=viewPager.getCurrentItem();            viewPager.setCurrentItem(index+1);            //改变小圆点            setSelectedPoint(index+1);            //延迟发送消息            sendEmptyMessageDelayed(1,2000);        }    };    private ViewPager viewPager;    private LinearLayout linPoint;    private ImageView[] imgArray;    private List<String> list;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        viewPager = (ViewPager) findViewById(R.id.vp);        linPoint = (LinearLayout) findViewById(R.id.linpoint);        //数据.....装的是path路径        list = new ArrayList<>();        list.add("https://ss0.bdstatic.com/94oJfD_bAAcT8t7mm9GUKT-xh_/timg?image&quality=100&size=b4000_4000&sec=1510576227&di=8c199118d3ece98e0565e9ae0c751894&src=http://www.5577.com/up/2017-8/15029516238492643.jpg");        list.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1510585834296&di=a42b00c2d1c5b2903960ecc5c391a5a0&imgtype=0&src=http%3A%2F%2Fwww.5577.com%2Fup%2F2017-8%2F15029516239761152.jpg");        list.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1510585834296&di=fdb5e7f458f947ad1cdb3154a152de6e&imgtype=0&src=http%3A%2F%2Fwx1.sinaimg.cn%2Forj480%2F006Keh8Jly1fidr0yrc7xj30hs0a0jrl.jpg");        list.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1510585834295&di=a9198d0f22ff74259f71557bee091d6f&imgtype=0&src=http%3A%2F%2Fwww.xz7.com%2Fup%2F2017-8%2F201781085651764760.jpg");        list.add("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1510585834295&di=a2098f90037db615b7fef2ae0f100173&imgtype=0&src=http%3A%2F%2F1.pic.pc6.com%2Fthumb%2Fup%2F2017-08%2F15016384112136643_600_0.jpg");        imgArray=new ImageView[list.size()];        viewPager.setAdapter(new MyPagerAdapter(this,list));        //使页面 可以向左滑动        viewPager.setCurrentItem(list.size()*100);        //实现自动播放        myHandler.sendEmptyMessageDelayed(1,2000);        initPoint();    }    //0,1,2,3,4,......Integer.maxvalue    public  void setSelectedPoint(int pageIndex){        //循环imageview控件        //计算要选中小圆点的下标        int selectedIndex=pageIndex%list.size();        for(int i=0;i<list.size();i++){            if(i==selectedIndex){                imgArray[i].setImageResource(R.drawable.point_selected);            }else{                imgArray[i].setImageResource(R.drawable.point_un_selected);            }        }    }    /**     * 初使化小圆点     */    private void initPoint() {        for(int i=0;i<list.size();i++){            //第一步            ImageView img=new ImageView(this);            //图片的缩放方式            img.setScaleType(ImageView.ScaleType.FIT_XY);            if(i==0){                //使用shape画小圆点                img.setImageResource(R.drawable.point_un_selected);            }else{                img.setImageResource(R.drawable.point_un_selected);            }            //img对象 设置控件的宽度与高度            LinearLayout.LayoutParams params=new LinearLayout.LayoutParams(30,30);            //设置右间隔 10px            params.setMargins(0,0,10,0);            //添加到容器中            linPoint.addView(img,params);//第三步            //添加到数组中            imgArray[i]=img;        }    }}
5.创建视图
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="cuishihao.bwie.com.lianxi2.MainActivity">    <android.support.v4.view.ViewPager        android:layout_width="match_parent"        android:layout_height="200dp"        android:id="@+id/vp"></android.support.v4.view.ViewPager>    <!-- 用来存放 小圆点  Imageview  viewgroup.addView -->    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal"        android:id="@+id/linpoint"        android:gravity="center"        android:layout_alignBottom="@+id/vp">    </LinearLayout></RelativeLayout>
6.  自动轮播时  小圆点的颜色，在value中
<?xml version="1.0" encoding="utf-8"?><resources>    <color name="colorPrimary">#3F51B5</color>    <color name="colorPrimaryDark">#303F9F</color>    <color name="colorAccent">#FF4081</color></resources>
<?xml version="1.0" encoding="utf-8"?><resources></resources>

<resources>    <!-- Base application theme. -->    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">        <!-- Customize your theme here. -->        <item name="colorPrimary">@color/colorPrimary</item>        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>        <item name="colorAccent">@color/colorAccent</item>    </style></resources>
7.  在drawable中  建立两个  一个是轮播选中是 一个是没选中
  选中point_selected 
<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"    android:shape="oval">    <solid android:color="#ff0000"></solid></shape>
没选中是point_un_selected
<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"    android:shape="oval">    <solid android:color="#ccc"></solid></shape>
8.在权限中
<uses-permission android:name="android.permission.INTERNET"></uses-permission><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission><uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
  <application    android:allowBackup="true"    android:icon="@mipmap/ic_launcher"    android:label="@string/app_name"    android:roundIcon="@mipmap/ic_launcher_round"    android:supportsRtl="true"    android:theme="@style/AppTheme"    android:name=".MyApplication"    >
还要记得导入imaged的jar包

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