ViewPager的功能与使用

ViewPager用于实现多页面的切换效果，该类存在于Google的兼容包里面，所以在引用时记得在BuilldPath中加入“android-support-v4.jar”.

新效果有如下特征：

[1] 当前显示一组界面中的其中一个界面。

[2] 当用户通过左右滑动界面时，当前的屏幕显示当前界面和下一个界面的一部分。

[3]滑动结束后，界面自动跳转到当前选择的界面中

使用贴上源码如下：

XML：

<?xml version="1.0" encoding="utf-8"?>

<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/whatsnew_viewpager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center" >

<android.support.v4.view.PagerTitleStrip
android:id="@+id/pagertitle"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_gravity="bottom"
android:background="#0000"
android:textColor="#ffff" />
</android.support.v4.view.ViewPager>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
>

<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:layout_marginBottom="30dp"
android:gravity="center_horizontal" >

<ImageView
android:id="@+id/page0"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="matrix"
android:src="@drawable/page_now" />
<ImageView
android:id="@+id/page1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:scaleType="matrix"
android:src="@drawable/page" />
<ImageView
android:id="@+id/page2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:scaleType="matrix"
android:src="@drawable/page" />
<ImageView
android:id="@+id/page3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:scaleType="matrix"
android:src="@drawable/page" />
<ImageView
android:id="@+id/page4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:scaleType="matrix"
android:src="@drawable/page" />
<ImageView
android:id="@+id/page5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:scaleType="matrix"
android:src="@drawable/page" />

</LinearLayout>

</LinearLayout>

</FrameLayout>


代码：
package com.example.viewpaper_demo;

import java.util.ArrayList;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.widget.ImageView;

public class MainActivity extends Activity implements OnPageChangeListener {
private ViewPager mViewPager;
private ImageView mPage0;
private ImageView mPage1;
private ImageView mPage2;
private ImageView mPage3;
private ImageView mPage4;
private ImageView mPage5;

private int currIndex = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager=(ViewPager)this.findViewById(R.id.whatsnew_viewpager);
mViewPager.setOnPageChangeListener(this);

mPage0 = (ImageView)findViewById(R.id.page0);
mPage1 = (ImageView)findViewById(R.id.page1);
mPage2 = (ImageView)findViewById(R.id.page2);
mPage3 = (ImageView)findViewById(R.id.page3);
mPage4 = (ImageView)findViewById(R.id.page4);
mPage5 = (ImageView)findViewById(R.id.page5);

LayoutInflater mLi=LayoutInflater.from(this);
View view1 = mLi.inflate(R.layout.whats1, null);
View view2 = mLi.inflate(R.layout.whats2, null);
View view3 = mLi.inflate(R.layout.whats3, null);
View view4 = mLi.inflate(R.layout.whats4, null);
View view5 = mLi.inflate(R.layout.whats5, null);
View view6 = mLi.inflate(R.layout.whats6, null);
//每个页面的view数据
final ArrayList<View> views = new ArrayList<View>();
views.add(view1);
views.add(view2);
views.add(view3);
views.add(view4);
views.add(view5);
views.add(view6);

PagerAdapter mPagerAdapter=new PagerAdapter(){

@Override
public int getCount() {
// TODO Auto-generated method stub
return views.size();
}

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
// TODO Auto-generated method stub
return arg0==arg1;
}

@Override
public void destroyItem(View container, int position, Object object) {
// TODO Auto-generated method stub
((ViewPager)container).removeView(views.get(position));
}

@Override
public Object instantiateItem(View container, int position) {
// TODO Auto-generated method stub
((ViewPager)container).addView(views.get(position));
return views.get(position);
}

};
mViewPager.setAdapter(mPagerAdapter);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub

}

public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub

}

public void onPageSelected(int arg0) {//实现亮点随着界面变换而变换
// TODO Auto-generated method stub
switch (arg0) {
case 0:
mPage0.setImageDrawable(getResources().getDrawable(R.drawable.page_now));
mPage1.setImageDrawable(getResources().getDrawable(R.drawable.page));
break;
case 1:
mPage1.setImageDrawable(getResources().getDrawable(R.drawable.page_now));
mPage0.setImageDrawable(getResources().getDrawable(R.drawable.page));
mPage2.setImageDrawable(getResources().getDrawable(R.drawable.page));
break;
case 2:
mPage2.setImageDrawable(getResources().getDrawable(R.drawable.page_now));
mPage1.setImageDrawable(getResources().getDrawable(R.drawable.page));
mPage3.setImageDrawable(getResources().getDrawable(R.drawable.page));
break;
case 3:
mPage3.setImageDrawable(getResources().getDrawable(R.drawable.page_now));
mPage4.setImageDrawable(getResources().getDrawable(R.drawable.page));
mPage2.setImageDrawable(getResources().getDrawable(R.drawable.page));
break;
case 4:
mPage4.setImageDrawable(getResources().getDrawable(R.drawable.page_now));
mPage3.setImageDrawable(getResources().getDrawable(R.drawable.page));
mPage5.setImageDrawable(getResources().getDrawable(R.drawable.page));
break;
case 5:
mPage5.setImageDrawable(getResources().getDrawable(R.drawable.page_now));
mPage4.setImageDrawable(getResources().getDrawable(R.drawable.page));
break;
}
currIndex = arg0;
}
public void start(View v) {
Log.d("Infor", "dao l ");
this.finish();
}
}


PS:在ViewPager的第六个界面有个按钮，对其监听使用的方法是在该界面布局的XML文件中对于该Button使用android:onClick="start"
来进行定义监听处理的方法。注意使用该方法定义的函数必须有形参（View v），否则便会报错提示。

效果图：





想要实现无限循环界面切换，只要针对PagerAdapter进行处理一下即可：

PagerAdapter mPagerAdapter=new PagerAdapter(){

@Override
public int getCount() {
// TODO Auto-generated method stub
//return views.size();
return Integer.MAX_VALUE;
}

@Override
public boolean isViewFromObject(View arg0, Object arg1) {
// TODO Auto-generated method stub
return arg0==arg1;
}

@Override
public void destroyItem(View container, int position, Object object) {
// TODO Auto-generated method stub
((ViewPager)container).removeView(views.get(position%views.size()));
}

@Override
public Object instantiateItem(View container, int position) {
// TODO Auto-generated method stub
((ViewPager)container).addView(views.get(position%views.size()));
return views.get(position%views.size());
}

};
mViewPager.setAdapter(mPagerAdapter);