Android菜鸟的成长笔记（27）——ViewPager的使用

ViewPager是Android 3.0以上可以使用的API。

一、ViewPager能干什么？

1、微信5.0中连带滑动用ViewPager可以轻松实现。

2、实现类似于新浪微博的导航引导界面。

3、实现其他导航或菜单。

二、ViewPager的使用

1、添加布局

<LinearLayout 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="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_gravity="center"/>  
</LinearLayout>

2、加载要显示的布局文件（View）

        LayoutInflater lf = getLayoutInflater().from(this);
        view1 = lf.inflate(R.layout.layout_0, null);
        view2 = lf.inflate(R.layout.layout_1, null);
        view3 = lf.inflate(R.layout.layout_2, null);

3、创建View集合

        mListViews = new ArrayList<View>();
        mListViews.add(view1);
        mListViews.add(view2);
        mListViews.add(view3);

4、创建PagerAdapter

ViewPager的适配器是PagerAdapter，要实现PagerAdapter至少要实现以下方法：

（1）instantiateItem(ViewGroup, int) //添加

（2）destroyItem(ViewGroup, int, Object)     //删除

（3）getCount()

（4）isViewFromObject(View, Object)

    private class MyPageAdapter extends PagerAdapter {
    	private List<View> mListViews;
    	
    	public MyPageAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}
    	
    	/**
    	 * 删除页卡
    	 */
    	@Override
    	public void destroyItem(View container, int position, Object object) {
    		((ViewPager) container).removeView(mListViews.get(position));
    	}
    	
    	
    	/**
    	 * 实例化页卡
    	 */
    	@Override
    	public Object instantiateItem(View container, int position) {
    		((ViewPager)container).addView(mListViews.get(position));
    		return mListViews.get(position);
    	}
    	
    	/**
    	 * 返回页卡的数量
    	 */
		@Override
		public int getCount() {
			return mListViews.size();
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {
			return arg0 == arg1; //官方提示这样写
		}
    	
    }

5、配置适配器

mViewPager.setAdapter(new MyPageAdapter(mListViews));

全部代码如下：

package com.example.viewpagetest;

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

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.View;

public class MainActivity extends Activity {
	private List<View> mListViews;
	private View view1;
	private View view2;
	private View view3;
	private ViewPager mViewPager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        mViewPager = (ViewPager) findViewById(R.id.viewpager);
        
        //加载要显示的选项卡
        LayoutInflater lf = getLayoutInflater().from(this);
        view1 = lf.inflate(R.layout.layout_0, null);
        view2 = lf.inflate(R.layout.layout_1, null);
        view3 = lf.inflate(R.layout.layout_2, null);
      
        mListViews = new ArrayList<View>();
        mListViews.add(view1);
        mListViews.add(view2);
        mListViews.add(view3);
        
        mViewPager.setAdapter(new MyPageAdapter(mListViews));
        
    }
    
    private class MyPageAdapter extends PagerAdapter {
    	private List<View> mListViews;
    	
    	public MyPageAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}
    	
    	/**
    	 * 删除页卡
    	 */
    	@Override
    	public void destroyItem(View container, int position, Object object) {
    		((ViewPager) container).removeView(mListViews.get(position));
    	}
    	
    	
    	/**
    	 * 实例化页卡
    	 */
    	@Override
    	public Object instantiateItem(View container, int position) {
    		((ViewPager)container).addView(mListViews.get(position));
    		return mListViews.get(position);
    	}
    	
    	/**
    	 * 返回页卡的数量
    	 */
		@Override
		public int getCount() {
			return mListViews.size();
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {
			return arg0 == arg1; //官方提示这样写
		}
    	
    }
}

各个页面代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <TextView 
    	android:layout_width="match_parent"
    	android:layout_height="match_parent"
    	android:text="1"
    	android:gravity="center"
    	android:textSize="120sp"
    	android:textColor="#33b5e5"
    />
</LinearLayout>

运行效果：

三、实现微信的菜单联动

android.support.v4.view包中的接口和类如下：

从上面图片中我们可以看到PagerTabStrip和PagerTitleStrip

从字面意思上理解，PagerTabStrip是可以点击的导航选项卡，而PagerTitleStrip是不能互动的（点击）的导航选项卡。

下面我们修改布局文件如下：

<LinearLayout 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="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_gravity="center">
    	<android.support.v4.view.PagerTabStrip
    	    android:id="@+id/pagertab"
    	    android:layout_width="wrap_content"    
            android:layout_height="wrap_content"    
            android:layout_gravity="top"/>    
	</android.support.v4.view.ViewPager>
</LinearLayout>

layout_gravity可以设置Tab的位置

修改MainActvity

        mTitleList = new ArrayList<String>();
        mTitleList.add("聊天");
        mTitleList.add("发现");
        mTitleList.add("通讯录");

在PagerAdapter中添加下面代码：

@Override
public CharSequence getPageTitle(int position) {
	return mTitleList.get(position);
}

贴出全部代码，如下：

package com.example.viewpagetest;

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

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.View;

public class MainActivity extends Activity {
	private List<String> mTitleList;
	private List<View> mListViews;   
	private ViewPager mViewPager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        mViewPager = (ViewPager) findViewById(R.id.viewpager);
        
        //加载要显示的选项卡
        LayoutInflater lf = getLayoutInflater().from(this);
        View view1 = lf.inflate(R.layout.layout_0, null);
        View view2 = lf.inflate(R.layout.layout_1, null);
        View view3 = lf.inflate(R.layout.layout_2, null);
      
        mListViews = new ArrayList<View>();
        mListViews.add(view1);
        mListViews.add(view2);
        mListViews.add(view3);
        
        mTitleList = new ArrayList<String>();
        mTitleList.add("聊天");
        mTitleList.add("发现");
        mTitleList.add("通讯录");
        
        
        mViewPager.setAdapter(new MyPageAdapter(mListViews));
        
    }
    
    private class MyPageAdapter extends PagerAdapter {
    	private List<View> mListViews;
    	
    	public MyPageAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}
    	
    	/**
    	 * 删除页卡
    	 */
    	@Override
    	public void destroyItem(View container, int position, Object object) {
    		((ViewPager) container).removeView(mListViews.get(position));
    	}
    	
    	
    	/**
    	 * 实例化页卡
    	 */
    	@Override
    	public Object instantiateItem(View container, int position) {
    		((ViewPager)container).addView(mListViews.get(position));
    		return mListViews.get(position);
    	}
    	
    	/**
    	 * 返回页卡的数量
    	 */
		@Override
		public int getCount() {
			return mListViews.size();
		}

		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {
			return arg0 == arg1; //官方提示这样写
		}
		
		/**
		 * 设置Tab
		 */
		@Override
		public CharSequence getPageTitle(int position) {
			return mTitleList.get(position);
		}
    }
}

运行效果：

上面虽然有了Tab，并能随着页面的切换改变，但是这个并不是我们要达到的效果。下面我们自己做一个静态的Tab底部和一个动画来实现。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#eeeeee"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="fill_parent"
        android:layout_height="32.0dip"
        android:background="#eeeeee" >

        <TextView
            android:id="@+id/text1"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1.0"
            android:gravity="center"
            android:text="聊天"
            android:textColor="#000000"
            android:textSize="16.0dip" />

        <TextView
            android:id="@+id/text2"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1.0"
            android:gravity="center"
            android:text="发现"
            android:textColor="#000000"
            android:textSize="16.0dip" />

        <TextView
            android:id="@+id/text3"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_weight="1.0"
            android:gravity="center"
            android:text="通讯录"
            android:textColor="#000000"
            android:textSize="16.0dip" />
    </LinearLayout>

    <ImageView
        android:id="@+id/cursor"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:scaleType="matrix"
        android:src="@drawable/a"/>
	<ImageView
	    android:layout_width="match_parent"
	    android:layout_height="1px"
	    android:background="#cccccc"/>
    <android.support.v4.view.ViewPager
        android:id="@+id/vPager"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_gravity="center"
        android:layout_weight="1.0"
        android:flipInterval="30"
        android:background="#ffffff"
        android:persistentDrawingCache="animation" />
</LinearLayout>

package com.example.wuye001;

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

import android.app.Activity;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
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.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

	private ViewPager viewPager;//页卡内容
	private ImageView imageView;// 动画图片
	private TextView textView1,textView2,textView3;
	private List<View> views;// Tab页面列表
	private int offset = 0;// 动画图片偏移量
	private int currIndex = 0;// 当前页卡编号
	private int bmpW;// 动画图片宽度
	private View view1,view2,view3;//各个页卡
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		InitImageView();
		InitTextView();
		InitViewPager();
	}

	private void InitViewPager() {
		viewPager=(ViewPager) findViewById(R.id.vPager);
		views=new ArrayList<View>();
		LayoutInflater inflater=getLayoutInflater();
		view1=inflater.inflate(R.layout.layout_0, null);
		view2=inflater.inflate(R.layout.layout_1, null);
		view3=inflater.inflate(R.layout.layout_2, null);
		views.add(view1);
		views.add(view2);
		views.add(view3);
		viewPager.setAdapter(new MyViewPagerAdapter(views));
		viewPager.setCurrentItem(0);
		viewPager.setOnPageChangeListener(new MyOnPageChangeListener());
	}
	 /**
	  *  初始化头标
	  */

	private void InitTextView() {
		textView1 = (TextView) findViewById(R.id.text1);
		textView2 = (TextView) findViewById(R.id.text2);
		textView3 = (TextView) findViewById(R.id.text3);

		textView1.setOnClickListener(new MyOnClickListener(0));
		textView2.setOnClickListener(new MyOnClickListener(1));
		textView3.setOnClickListener(new MyOnClickListener(2));
	}

	/**
	 * 初始化动画，这个就是页卡滑动时，下面的横线也滑动的效果，在这里需要计算一些数据
	 */

	private void InitImageView() {
		imageView= (ImageView) findViewById(R.id.cursor);
		bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.a).getWidth();// 获取图片宽度
		DisplayMetrics dm = new DisplayMetrics();
		getWindowManager().getDefaultDisplay().getMetrics(dm);
		int screenW = dm.widthPixels;// 获取分辨率宽度
		offset = (screenW / 3 - bmpW) / 2;// 计算偏移量
		Matrix matrix = new Matrix();
		matrix.postTranslate(offset, 0);
		imageView.setImageMatrix(matrix);// 设置动画初始位置
	}
	/** 
	 *     
	 * 头标点击监听 3 */
	private class MyOnClickListener implements OnClickListener{
        private int index=0;
        public MyOnClickListener(int i){
        	index=i;
        }
		public void onClick(View v) {
			viewPager.setCurrentItem(index);			
		}
		
	}
	
	public class MyViewPagerAdapter extends PagerAdapter{
		private List<View> mListViews;
		
		public MyViewPagerAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}

		@Override
		public void destroyItem(ViewGroup container, int position, Object object) 	{	
			container.removeView(mListViews.get(position));
		}


		@Override
		public Object instantiateItem(ViewGroup container, int position) {			
			 container.addView(mListViews.get(position), 0);
			 return mListViews.get(position);
		}

		@Override
		public int getCount() {			
			return  mListViews.size();
		}
		
		@Override
		public boolean isViewFromObject(View arg0, Object arg1) {			
			return arg0==arg1;
		}
	}

    public class MyOnPageChangeListener implements OnPageChangeListener{

    	int one = offset * 2 + bmpW;// 页卡1 -> 页卡2 偏移量
		int two = one * 2;// 页卡1 -> 页卡3 偏移量
		public void onPageScrollStateChanged(int arg0) {
			
			
		}

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

		public void onPageSelected(int arg0) {
			/*两种方法，这个是一种，下面还有一种，显然这个比较麻烦
			Animation animation = null;
			switch (arg0) {
			case 0:
				if (currIndex == 1) {
					animation = new TranslateAnimation(one, 0, 0, 0);
				} else if (currIndex == 2) {
					animation = new TranslateAnimation(two, 0, 0, 0);
				}
				break;
			case 1:
				if (currIndex == 0) {
					animation = new TranslateAnimation(offset, one, 0, 0);
				} else if (currIndex == 2) {
					animation = new TranslateAnimation(two, one, 0, 0);
				}
				break;
			case 2:
				if (currIndex == 0) {
					animation = new TranslateAnimation(offset, two, 0, 0);
				} else if (currIndex == 1) {
					animation = new TranslateAnimation(one, two, 0, 0);
				}
				break;
				
			}
			*/
			Animation animation = new TranslateAnimation(one*currIndex, one*arg0, 0, 0);//显然这个比较简洁，只有一行代码。
			currIndex = arg0;
			animation.setFillAfter(true);// True:图片停在动画结束位置
			animation.setDuration(300);
			imageView.startAnimation(animation);
		}
    	
    }
}

运行效果：