ViewPager的简单用法

ViewPager的作用是让页面滑动。

左右滑动分别显示3个页面

代码

在主布局文件放入一个ViewPager

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

</RelativeLayout>

创建每个可以滑动的页面(创建xml文件)

layout1.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    
    <TextView 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="第一个页面"
    android:layout_centerInParent="true"
    android:gravity="center|center_horizontal"
    />

</RelativeLayout>

layout2.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    
<TextView 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="第二个页面"
    android:layout_centerInParent="true"
    android:gravity="center|center_horizontal"
    />
</RelativeLayout>

layout3.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    
    <TextView 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="第三个页面"
    android:layout_centerInParent="true"
    android:gravity="center|center_horizontal"
    />

</RelativeLayout>

MainActivity.java

package com.example.viewpager;

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;

public class MainActivity extends Activity {
	private ViewPager viewPager;
	private View view1;
	private View view2;
	private View view3;
	private ArrayList<View> viewList;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		//获取ViewPager对象
		viewPager =(ViewPager)findViewById(R.id.viewpager);
		
		initView();		
	}
	
	private void initView()
	{
		//加载布局文件(页卡)，并转换为View对象
		LayoutInflater lf = getLayoutInflater().from(this);
		view1 = lf.inflate(R.layout.layout1, null);
		view2 = lf.inflate(R.layout.layout2, null);
		view3 = lf.inflate(R.layout.layout3, null);
		
		//将View对象放入数组
		viewList = new ArrayList<View>();
		viewList.add(view1);
		viewList.add(view2);
		viewList.add(view3);
		
		//创建适配器对象		
		ViewPagerAdapter vpa = new ViewPagerAdapter();
		
		//将适配器设置与ViewPager进行绑定
		viewPager.setAdapter(vpa);
	}
	
	//创建适配器
	class ViewPagerAdapter extends PagerAdapter
	{
		@Override		
		public  void destroyItem(ViewGroup container,int position,Object ibject){
			//删除页卡
			container.removeView(viewList.get(position));
		}
		@Override
		public Object instantiateItem(ViewGroup container,int position){
			//添加页卡
			container.addView(viewList.get(position));
			return viewList.get(position);
		}

		@Override
		public int getCount() {			
			//返回页卡的数量
			return viewList.size();
		}

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

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}