Android 使用ViewPager实现左右循环滑动图片

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

 

<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

 

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];
    }

Android 使用ViewPager实现左右循环滑动图片