Android ViewPager加载图片效果

<?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:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.fly.viewpagerbanner.MainActivity"> <android.support.v4.view.ViewPager  android:id="@+id/viewpager"  android:layout_above="@+id/ll"  android:layout_width="fill_parent"  android:layout_height="fill_parent" /> <LinearLayout  android:id="@+id/ll"  android:layout_marginTop="10.0dip"  android:orientation="horizontal"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:layout_marginBottom="24.0dip"  android:layout_alignParentBottom="true"  android:layout_centerHorizontal="true"/></RelativeLayout>

package com.example.fly.viewpagerbanner;import android.support.v4.view.ViewPager;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.Toast;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;/** * 类名： * 类描述：ViewPager展示图片 * 创建人：fly * 创建日期： 2017/1/16. * 版本：V1.0 */public class MainActivity extends AppCompatActivity implements ViewPager.OnPageChangeListener,View.OnClickListener { private ViewPager vp; private ViewPagerAdapter vpAdapter; private List<Map<String, Object>> data; private int lastValue = -1; // 是不是最后一张图片 private ImageView[] dots; //底部小点图片 private int currentIndex; //记录当前选中位置 @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  //  Intent intent = new Intent();//  intent.putStringArrayListExtra("GalleryPlusActivity",ArrayList<String>); // 怎么传递集合  ArrayList<String> imageLists = getIntent().getStringArrayListExtra("GalleryPlusActivity"); // 动态获取展示图片的集合  data = getData(imageLists);  vp = (ViewPager) findViewById(R.id.viewpager);  vpAdapter = new ViewPagerAdapter(data,this);  vp.setAdapter(vpAdapter);  vp.addOnPageChangeListener(this);  initDots();//初始化底部小点 } //这个方法长度是动态的，可以改成你从服务器获取的图片，这样数量就不确定啦 public List<Map<String, Object>> getData(ArrayList<String> imageLists) {  List<Map<String, Object>> mData = new ArrayList<>();//  if (imageLists != null && imageLists.size() > 0) {//   for (int i = 0; i < imageLists.size(); i++) {//    Map<String, Object> map = new HashMap<>();//    map.put("url", imageLists.get(i));//    map.put("view", new ImageView(this));//    mData.add(map);//   }//  }  Map<String, Object> map = new HashMap<>();  map.put("url", "http://img2.duitang.com/uploads/item/201207/19/20120719132725_UkzCN.jpeg");  map.put("view", new ImageView(this));  mData.add(map);  Map<String, Object> map1 = new HashMap<>();  map1.put("url", "http://img4.duitang.com/uploads/item/201404/24/20140424195028_vtvZu.jpeg");  map1.put("view", new ImageView(this));  mData.add(map1);  Map<String, Object> map2 = new HashMap<>();  map2.put("url", "http://download.pchome.net/wallpaper/pic-5041-8-240x320.jpg");  map2.put("view", new ImageView(this));  mData.add(map2);  Map<String, Object> map3 = new HashMap<>();  map3.put("url", "http://www.mangowed.com/uploads/allimg/130425/572-130425105311304.jpg");  map3.put("view", new ImageView(this));  mData.add(map3);  return mData; } private void initDots() {  LinearLayout.LayoutParams mLayoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);  mLayoutParams.setMargins(3, 0, 3, 0);  LinearLayout ll = (LinearLayout) findViewById(R.id.ll);  dots = new ImageView[data.size()];  //循环取得小点图片  for (int i = 0; i < data.size(); i++) {   dots[i] = new ImageView(this);   dots[i].setLayoutParams(mLayoutParams);   dots[i].setBackgroundResource(R.drawable.dot);   dots[i].setEnabled(true);//都设为灰色   dots[i].setOnClickListener(this);   dots[i].setTag(i);//设置位置tag，方便取出与当前位置对应   ll.addView(dots[i]);  }  currentIndex = 0;  dots[currentIndex].setEnabled(false);//设置为白色，即选中状态 } private void setCurView(int position) { /**设置当前的引导页*/  if (position < 0 || position >= data.size()) {return;}  vp.setCurrentItem(position); } private void setCurDot(int position) { /**设置当前引导小点的选中*/  if (position < 0 || position > data.size() - 1 || currentIndex == position) {return;}  dots[position].setEnabled(false);  dots[currentIndex].setEnabled(true);  currentIndex = position; } @Override //当前页面被滑动时调用 public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {  lastValue = position; } @Override public void onPageSelected(int position) {     //当新的页面被选中时调用  setCurDot(position); //设置底部小点选中状态 } @Override public void onPageScrollStateChanged(int state) {   //当滑动状态改变时调用  if(state == 0){   if(lastValue == data.size()-1){    Toast.makeText(this, "已经是最后一张了", Toast.LENGTH_SHORT).show();   }  } } @Override public void onClick(View v) {  int position = (Integer)v.getTag();  setCurView(position);  setCurDot(position); }}

package com.example.fly.viewpagerbanner;import android.content.Context;import android.support.v4.view.PagerAdapter;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import com.bumptech.glide.Glide;import com.bumptech.glide.load.engine.DiskCacheStrategy;import java.util.List;import java.util.Map;public class ViewPagerAdapter extends PagerAdapter { Context context; List<Map<String, Object>> viewLists; public ViewPagerAdapter(List<Map<String, Object>> lists, Context context) {  this.viewLists = lists;  this.context = context; } @Override public int getCount() {  //获得size  return viewLists.size(); } @Override public boolean isViewFromObject(View view, Object object) {  return view == object; } @Override public void destroyItem(ViewGroup view, int position, Object object) { //销毁Item  ImageView x = (ImageView) viewLists.get(position).get("view");  x.setScaleType(ImageView.ScaleType.FIT_CENTER);  view.removeView(x); } @Override public Object instantiateItem(ViewGroup view, int position){ //实例化Item  ImageView imageView = (ImageView) viewLists.get(position).get("view");  imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);  Glide.with(context)    .load(viewLists.get(position).get("url").toString())//    .placeholder(R.mipmap.new_default)    .error(R.mipmap.ic_launcher)    .diskCacheStrategy(DiskCacheStrategy.RESULT)    .into(imageView);  view.addView(imageView, 0);  return viewLists.get(position).get("view"); }}