安卓中无限轮播的实现

在Activity中

package com.bwie.singletouch;

import java.util.ArrayList;
import java.util.List;

import com.bwie.singletouch.adapter.MyPagerAdapter;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;

public class MainActivity extends Activity {

private ViewPager viewPager;
private LinearLayout ll_dots;
private String[] imageUrls = new String[] {
"http://img02.sogoucdn.com/app/a/100520093/d5f60dc98baba8e4-2b87ae6dab503410-5d75f8577d874c4cca46a9d851c2cc90.jpg",
"http://img3.3lian.com/2013/v11/5/d/31.jpg",
"http://img2.cache.netease.com/house/2014/1/9/20140109170846a57c0_550.jpg",
"http://img04.sogoucdn.com/app/a/100520093/68eeac8aabfa792f-c4380846209ff175-2b662cb95e36b6bf8926f37282291de0.jpg" };
Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
if (msg.what == 0) {
// 获取viewPager当前所在的页码索引值
int currentItem = viewPager.getCurrentItem();
currentItem++;
viewPager.setCurrentItem(currentItem);
handler.sendEmptyMessageDelayed(0, 2000);
}
};
};
private List<ImageView> dotsList;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 找控件
findView();
viewPager.setAdapter(new MyPagerAdapter(imageUrls, this, handler));
// 设置当前的一个条目值
viewPager.setCurrentItem(imageUrls.length * 5000);
// 初始化小圆点
initDots();
viewPager.setOnPageChangeListener(new OnPageChangeListener() {

@Override
public void onPageSelected(int arg0) {
for (int i = 0; i < dotsList.size(); i++) {
if (i == arg0 % imageUrls.length) {
dotsList.get(i).setImageResource(R.drawable.dots_focus);
} else {
dotsList.get(i)
.setImageResource(R.drawable.dots_normal);
}
}
}

@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {

}

@Override
public void onPageScrollStateChanged(int arg0) {

}
});
handler.sendEmptyMessageDelayed(0, 2000);
}

private void initDots() {
dotsList = new ArrayList<ImageView>();
dotsList.clear();
ll_dots.removeAllViews();
for (int i = 0; i < imageUrls.length; i++) {
// 画出圆点
ImageView imageView = new ImageView(this);
//
if (i == 0) {
imageView.setImageResource(R.drawable.dots_focus);
} else {
imageView.setImageResource(R.drawable.dots_normal);
}
// 宽和高 dp 相对像素
// 如果是真正开发，需要转成 px值 屏幕适配 dp---px
LayoutParams params = new LayoutParams(10, 10);
// 放到什么位置
params.setMargins(5, 0, 5, 0);
dotsList.add(imageView);
ll_dots.addView(imageView, params);
}

}

private void findView() {
viewPager = (ViewPager) findViewById(R.id.viewPager);
ll_dots = (LinearLayout) findViewById(R.id.ll_dots);
}
}

在MyPagerAdapter中

package com.bwie.singletouch.adapter;

import com.bwie.singletouch.MainActivity;
import com.lidroid.xutils.BitmapUtils;

import android.os.Handler;
import android.support.v4.view.PagerAdapter;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.ImageView;

public class MyPagerAdapter extends PagerAdapter {
private String[] imageUrls;
private MainActivity context;
private Handler handler;

public MyPagerAdapter(String[] imageUrls, MainActivity context,
Handler handler) {
super();
this.imageUrls = imageUrls;
this.context = context;
this.handler = handler;
}

@Override
public int getCount() {
return Integer.MAX_VALUE;
}

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == arg1;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
ImageView imageView = new ImageView(context);
imageView.setOnTouchListener(new OnTouchListener() {

@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// 手指按下的时候,停止自动轮播的任务
// 移除所有的消息及回调 null 移除所有
handler.removeCallbacksAndMessages(null);
break;
case MotionEvent.ACTION_UP:
handler.sendEmptyMessageDelayed(0, 2000);
break;
case MotionEvent.ACTION_CANCEL:
handler.sendEmptyMessageDelayed(0, 2000);
break;

default:
break;
}
return true;
}
});
BitmapUtils bitmapUtils = new BitmapUtils(context);
// 0 1 2 3 4 5 6 %4
// 0 1 2 3 0 1 2 ......
bitmapUtils.display(imageView, imageUrls[position % imageUrls.length]);

container.addView(imageView);
return imageView;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
// super.destroyItem(container, position, object);
container.removeView((View) object);
}
}

在drawable中写dots_focus.xml文件

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <corners android:radius="8dp" />

    <solid android:color="#ff0000" />

</shape>

在drawable中写 dots_normal.xml文件

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >

    <corners android:radius="8dp" />

    <solid android:color="#88000000" />

</shape>

在activity_main.xml布局中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}" >

    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="200dp" />

    <LinearLayout
        android:id="@+id/ll_dots"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@id/viewPager"
        android:gravity="center"
        android:orientation="horizontal" >
    </LinearLayout>

</RelativeLayout>

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