Android 中ViewPager 实现banner无限轮播效果

概述

本文实现了ViewPager展示广告无限轮播的效果图。该效果网上资源非常多，实现方式大同小异，这里我将其进行封装在一个自定义的LinearLayout布局中。里面包含了ViewPager，PagerAdapter，进度引导原点，图片显示，图片点击事件等功能。所有的操作都在该类内部进行，调用者只需要进行简单的配置即可。

下面将使用代码显示如何调用：

布局文件：activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:background="@android:color/holo_orange_dark"
android:layout_height="match_parent" >

<com.yuminfeng.myviewpager.ImageCycleView
android:id="@+id/cycleView"
android:layout_width="match_parent"
android:layout_height="120dp"
android:layout_margin="20dp" />

</LinearLayout>

MainActivity中的代码：

package com.yuminfeng.myviewpager;

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {

private ImageCycleView imageCycleView;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

imageCycleView = (ImageCycleView) findViewById(R.id.cycleView);
ArrayList<String> urlList = new ArrayList<>();

urlList.add(String.valueOf(R.drawable.pic1));
urlList.add(String.valueOf(R.drawable.pic2));
urlList.add(String.valueOf(R.drawable.pic3));
urlList.add(String.valueOf(R.drawable.pic4));
urlList.add(String.valueOf(R.drawable.pic5));

initCarsuelView(urlList);

}

private void initCarsuelView(ArrayList<String> urlList) {
ImageCycleView.ImageCycleViewListener mAdCycleViewListener = new ImageCycleView.ImageCycleViewListener() {
@Override
public void onImageClick(int position, View imageView) {
Toast.makeText(getApplicationContext(), "点击了:"+position, 0).show();
}

@Override
public void displayImage(String imageURL, ImageView imageView) {
imageView.setImageResource(Integer.valueOf(imageURL));
}
};
imageCycleView.setImageResources(urlList,mAdCycleViewListener);
imageCycleView.startImageCycle();

}

@Override
protected void onStop() {
super.onStop();
imageCycleView.pauseImageCycle();
}
}

以上便是简单的调用该封装的控件。使用起来非常简单，没有累赘的操作，代码清晰易懂。

下面便是自定义LinearLayout控件ImageCycleView，直接拿来使用即可，也可以自己定制它。

package com.yuminfeng.myviewpager;

import android.content.Context;
import android.os.Handler;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.LinearLayout;
import java.util.ArrayList;

/**
*自定义容器,用于循环播放广告
*
*/
public class ImageCycleView extends LinearLayout {
/**
* 上下文
*/
private Context mContext;
/**
* 图片轮播控件viewpager
*/
private ViewPager mAdvPager = null;
/**
* viewpager适配器
*/
private ImageCycleAdapter mAdvAdapter;
/**
* 图片轮播进度控件
*/
private ViewGroup mGroup;

/**
* ViewPager的显示的imageview
*/
private ImageView mImageView = null;

/**
* 滚动图片进度指示列表
*/
private ImageView[] dots = null;

/**
* 自动循环标志
*/
private boolean isStop;

public ImageCycleView(Context context) {
super(context);
init(context) ;
}

public ImageCycleView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context) ;
}

private void init(Context context){

mContext = context;

LayoutInflater.from(context).inflate(R.layout.ad_cycle_view, this);

mAdvPager = (ViewPager) findViewById(R.id.adv_pager);

mAdvPager.setOnPageChangeListener(new GuidePageChangeListener());

// 滚动图片右下指示器
mGroup = (ViewGroup) findViewById(R.id.circles);

}

/**
* 装填图片数据
*
* @param  :
* @param imageCycleViewListener
*/
public void setImageResources(ArrayList<String> imageUrlList,ImageCycleViewListener imageCycleViewListener) {

if(imageUrlList != null && imageUrlList.size() > 0){

this.setVisibility(View.VISIBLE);
}else{

this.setVisibility(View.GONE);
return;
}

// 清除
mGroup.removeAllViews();
// 图片广告数量
final int imageCount = imageUrlList.size();

dots = new ImageView[imageCount];

for (int i = 0; i < imageCount; i++) {

mImageView = new ImageView(mContext);
mImageView.setScaleType(ScaleType.CENTER_CROP);
dots[i] = mImageView;

if (i == 0) {
dots[i].setBackgroundResource(R.drawable.banner_dot_focus);
} else {
dots[i].setBackgroundResource(R.drawable.banner_dot_normal);
}
mGroup.addView(dots[i]);
}

mAdvAdapter = new ImageCycleAdapter(mContext, imageUrlList,imageCycleViewListener);
mAdvPager.setAdapter(mAdvAdapter);
}

/**
* 图片轮播(手动控制自动轮播与否，便于资源控件）
*/
public void startImageCycle() {
startImageTimerTask();
}

/**
* 暂停轮播—用于节省资源
*/
public void pauseImageCycle() {
stopImageTimerTask();
}

/**
* 图片滚动任务
*/
private void startImageTimerTask() {
isStop = false;
// 图片滚动
mHandler.postDelayed(mImageTimerTask, 3000);
}

/**
* 停止图片滚动任务
*/
private void stopImageTimerTask() {
isStop=true;
mHandler.removeCallbacks(mImageTimerTask);
}

private Handler mHandler = new Handler();

/**
* 图片自动轮播Task
*/
private Runnable mImageTimerTask = new Runnable() {
@Override
public void run() {
if (!isStop) {
mAdvPager.setCurrentItem(mAdvPager.getCurrentItem()+1);
}
}
};

/**
* 轮播图片监听
*
* @author minking
*/
private final class GuidePageChangeListener implements OnPageChangeListener {
@Override
public void onPageScrollStateChanged(int state) {

if (state == ViewPager.SCROLL_STATE_IDLE){ //处于停止状态
startImageTimerTask();
}else if(state == ViewPager.SCROLL_STATE_DRAGGING){ //用户正在滑动
stopImageTimerTask();
}
}
@Override
public void onPageScrolled(int position,float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {

position = position % dots.length;
// 设置图片滚动指示器背景
dots[position].setBackgroundResource(R.drawable.banner_dot_focus);
for (int i = 0; i < dots.length; i++) {
if (position != i) {
dots[i].setBackgroundResource(R.drawable.banner_dot_normal);
}
}
}
}

private class ImageCycleAdapter extends PagerAdapter {

/**
* 图片视图缓存列表
*/
private ArrayList<ImageView> mImageViewCacheList;

/**
* 图片资源列表URL
*/
private ArrayList<String> mAdURL;

/**
* 广告图片点击监听
*/
private ImageCycleViewListener mImageCycleViewListener;

private Context mContext;

public ImageCycleAdapter(Context context, ArrayList<String> mAdURL,ImageCycleViewListener imageCycleViewListener) {

this.mContext = context;
this.mAdURL = mAdURL;
mImageCycleViewListener = imageCycleViewListener;
mImageViewCacheList = new ArrayList<ImageView>();
}

@Override
public int getCount() {
return Integer.MAX_VALUE;
}
@Override
public boolean isViewFromObject(View view, Object obj) {
return view == obj;
}

@Override
public Object instantiateItem(ViewGroup container, final int position) {

String imageUrl = mAdURL.get(position % mAdURL.size());
ImageView imageView ;
if (mImageViewCacheList.isEmpty()) {
imageView = new ImageView(mContext);
imageView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
imageView.setScaleType(ScaleType.CENTER_CROP);
} else {
imageView = mImageViewCacheList.remove(0);
}
// 设置图片点击监听
imageView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mImageCycleViewListener.onImageClick(position % mAdURL.size(), v);
}
});
imageView.setTag(imageUrl);
container.addView(imageView);
mImageCycleViewListener.displayImage(imageUrl, imageView);
return imageView;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
ImageView view = (ImageView) object;
mAdvPager.removeView(view);
mImageViewCacheList.add(view);
}

}

/**
* 轮播控件的监听事件
*
* @author minking
*/
public  interface ImageCycleViewListener {
/**
* 加载图片资源
*
* @param imageURL
* @param imageView
*/
void displayImage(String imageURL, ImageView imageView);

/**
* 单击图片事件
*
* @param position
* @param imageView
*/
void onImageClick(int position, View imageView);
}
}

里面涉及到的布局文件：ad_cycle_view.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ad_rl"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<android.support.v4.view.ViewPager
android:id="@+id/adv_pager"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</android.support.v4.view.ViewPager>

<LinearLayout
android:id="@+id/circles"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:gravity="center"
android:orientation="horizontal"
android:paddingBottom="5dp" >
</LinearLayout>

</RelativeLayout>

将上面两个文件分别放在对应的目录下，就可以直接使用了，是不是非常简单！！！