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");
 }
}