大家好，又见面了，我是你们的朋友全栈君。
ViewPager这个小demo实现的是可以左右循环滑动图片，下面带索引，滑到最后一页在往右滑动就要第一页，第一页往左滑动就到最后一页，先上效果图，用美女图片是我一贯的作风，呵呵
1. 首先看一些layout下的xml
代码语言：javascript复制<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<android.support.v4.view.ViewPager
android:id="@ id/viewPager"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<LinearLayout
android:id="@ id/viewGroup"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginBottom="30dp"
android:gravity="center_horizontal"
android:orientation="horizontal" >
</LinearLayout>
</RelativeLayout>
</FrameLayout>使用ViewPager首先需要引入android-support-v4.jar这个jar包。自己不要忘记加
代码语言：javascript复制package com.example.viewpagerdemo;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class TwoActivity extends Activity implements OnPageChangeListener{
/**
* ViewPager
*/
private ViewPager viewPager;
/**
* 装点点的ImageView数组
*/
private ImageView[] tips;
/**
* 装ImageView数组
*/
private ImageView[] mImageViews;
/**
* 图片资源id
*/
private int[] imgIdArray ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewGroup group = (ViewGroup)findViewById(R.id.viewGroup);
viewPager = (ViewPager) findViewById(R.id.viewPager);
//载入图片资源ID
imgIdArray = new int[]{R.drawable.item01, R.drawable.item02, R.drawable.item03, R.drawable.item04,
R.drawable.item05,R.drawable.item06, R.drawable.item07, R.drawable.item08};
//将点点加入到ViewGroup中
tips = new ImageView[imgIdArray.length];
for(int i=0; i<tips.length; i ){
ImageView imageView = new ImageView(this);
imageView.setLayoutParams(new LayoutParams(10,10));
tips[i] = imageView;
if(i == 0){
tips[i].setBackgroundResource(R.drawable.page_indicator_focused);
}else{
tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused);
}
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(new ViewGroup.LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
layoutParams.leftMargin = 5;
layoutParams.rightMargin = 5;
group.addView(imageView, layoutParams);
}
//将图片装载到数组中
mImageViews = new ImageView[imgIdArray.length];
for(int i=0; i<mImageViews.length; i ){
ImageView imageView = new ImageView(this);
mImageViews[i] = imageView;
imageView.setBackgroundResource(imgIdArray[i]);
}
//设置Adapter
viewPager.setAdapter(new MyAdapter());
//设置监听，主要是设置点点的背景
viewPager.setOnPageChangeListener(this);
//设置ViewPager的默认项, 设置为长度的100倍，这样子开始就能往左滑动
viewPager.setCurrentItem((mImageViews.length) * 100);
}
/**
*
* @author xiaanming
*
*/
public class MyAdapter extends PagerAdapter{
@Override
public int getCount() {
return Integer.MAX_VALUE;
}
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == arg1;
}
@Override
public void destroyItem(View container, int position, Object object) {
((ViewPager)container).removeView(mImageViews[position % mImageViews.length]);
}
/**
* 载入图片进去，用当前的position 除以 图片数组长度取余数是关键
*/
@Override
public Object instantiateItem(View container, int position) {
((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);
return mImageViews[position % mImageViews.length];
}
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageSelected(int arg0) {
setImageBackground(arg0 % mImageViews.length);
}
/**
* 设置选中的tip的背景
* @param selectItems
*/
private void setImageBackground(int selectItems){
for(int i=0; i<tips.length; i ){
if(i == selectItems){
tips[i].setBackgroundResource(R.drawable.page_indicator_focused);
}else{
tips[i].setBackgroundResource(R.drawable.page_indicator_unfocused);
}
}
}
}代码下载
上面的代码中，当只有3张图片或者2张图片的时候，滑动存在BUG问题的修改如下
- destroyItem(View container, int position, Object object)方法中不removeView
@Override
public void destroyItem(View container, int position, Object object) {
// ((ViewPager)container).removeView(mImageViews[position % mImageViews.length]);
}- instantiateItem(View container, int position)增加异常扑捉
@Override
public Object instantiateItem(View container, int position) {
try {
((ViewPager)container).addView(mImageViews[position % mImageViews.length], 0);
}catch(Exception e){
//handler something
}
return mImageViews[position % mImageViews.length];
}发布者：全栈程序员栈长，转载请注明出处：https://javaforall.cn/163205.html原文链接：https://javaforall.cn
