使用ViewPager能够得到不同view的切换效果

例如以下图，实现了四个view间的相互滑动

ViewPager 入门一_xmlViewPager 入门一_xml_02

一、新建项目，引入ViewPager控件

ViewPager。它是google SDk中自带的一个附加包的一个类，能够用来实现屏幕间的切换。

<LinearLayout 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:orientation="vertical"
    tools:context="com.skyfin.viewpage.MainActivity" >
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        >
    </android.support.v4.view.ViewPager>
</LinearLayout>


2、新建四个LinearLayout，用于滑动切换的视图
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"    
    android:background="@color/antiquewhite"
    android:gravity="center"
    android:orientation="vertical" >
    <TextView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="tab2"
        android:textSize="20dp"
        android:textColor="@color/black"
        />
</LinearLayout>


3加载代码段将视图加载Viewpager中
import android.R.id;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.PagerTabStrip;
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.MenuItem;
import android.view.View;
import android.view.ViewGroup;

public class MainActivity extends Activity {

    ViewPager ViewPager = null;
    public String TAG = "tag";
    ArrayList<View> viewContainter = new ArrayList<View>();
    ArrayList<String> titleContainer = new ArrayList<String>();

    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ViewPager = (ViewPager)findViewById(R.id.pager);

        View view1 = LayoutInflater.from(this).inflate(R.layout.tab1, null);
        View view2 = LayoutInflater.from(this).inflate(R.layout.tab2, null);
        View view3 = LayoutInflater.from(this).inflate(R.layout.tab3, null);
        View view4 = LayoutInflater.from(this).inflate(R.layout.tab4, null);
        //viewpager開始加入view
        viewContainter.add(view1);
        viewContainter.add(view2);
        viewContainter.add(view3);
        viewContainter.add(view4);


        ViewPager.setAdapter(new PagerAdapter() {

            //viewpager中的组件数量
            @Override
            public int getCount() {
                return viewContainter.size();
            }
          //滑动切换的时候销毁当前的组件
            @Override
            public void destroyItem(ViewGroup container, int position,
                    Object object) {
                ((ViewPager) container).removeView(viewContainter.get(position));
            }
          //每次滑动的时候生成的组件
            @Override
            public Object instantiateItem(ViewGroup container, int position) {
                ((ViewPager) container).addView(viewContainter.get(position));
                return viewContainter.get(position);
            }

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

            @Override
            public int getItemPosition(Object object) {
                return super.getItemPosition(object);
            }

        });

        ViewPager.setOnPageChangeListener(new OnPageChangeListener() {
            @Override
            public void onPageScrollStateChanged(int arg0) {
            }

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

            }

            @Override
            public void onPageSelected(int arg0) {

            }
        });

    }

    @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;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}


代码具体解释

1.定义一个ViewPager的容器

ViewPager ViewPager = null;
ArrayList<View> viewContainter = new ArrayList<View>();


2.初始化换View和ViewPager且加入到View的容器viewContainter中

View view1 = LayoutInflater.from(this).inflate(R.layout.tab1, null);
        View view2 = LayoutInflater.from(this).inflate(R.layout.tab2, null);
        View view3 = LayoutInflater.from(this).inflate(R.layout.tab3, null);
        View view4 = LayoutInflater.from(this).inflate(R.layout.tab4, null);
        //viewpager開始加入view
        viewContainter.add(view1);
        viewContainter.add(view2);
        viewContainter.add(view3);
        viewContainter.add(view4);


3.加入到PagerAdapter中而且设置监听

ViewPager.setAdapter(new PagerAdapter() {

            //viewpager中的组件数量
            @Override
            public int getCount() {
                return viewContainter.size();
            }
          //滑动切换的时候销毁当前的组件
            @Override
            public void destroyItem(ViewGroup container, int position,
                    Object object) {
                ((ViewPager) container).removeView(viewContainter.get(position));
            }
          //每次滑动的时候生成的组件
            @Override
            public Object instantiateItem(ViewGroup container, int position) {
                ((ViewPager) container).addView(viewContainter.get(position));
                return viewContainter.get(position);
            }

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

            @Override
            public int getItemPosition(Object object) {
                return super.getItemPosition(object);
            }

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

        ViewPager.setOnPageChangeListener(new OnPageChangeListener() {
            @Override
            public void onPageScrollStateChanged(int arg0) {
            }

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

            }

            @Override
            public void onPageSelected(int arg0) {

            }
        });


PageAdapter 必须重写的四个函数：


  • boolean isViewFromObject(View arg0, Object arg1)
  • int getCount() 
  • void destroyItem(ViewGroup container, int position,Object object)
  • Object instantiateItem(ViewGroup container, int position)


先看看各个函数，我们上面都做了什么吧：





​​​​



  2. @Override  
  3. public int getCount() {  
  4.     // TODO Auto-generated method stub  
  5.     return viewList.size();  
  6. }  

getCount():返回要滑动的VIew的个数






​​​​



  2. @Override  
  3. public void destroyItem(ViewGroup container, int position,  
  4.         Object object) {  
  5.     // TODO Auto-generated method stub  
  6.     container.removeView(viewList.get(position));  
  7. }  

destroyItem（）：从当前container中删除指定位置（position）的View;



​​​​



  2. @Override  
  3. public Object instantiateItem(ViewGroup container, int position) {  
  4.     // TODO Auto-generated method stub  
  5.         container.addView(viewList.get(position));  
  6.           
  7.           
  8.         return viewList.get(position);  
  9.     }  
  10. };  

instantiateItem()：做了两件事，第一：将当前视图加入到container中，第二：返回当前View



​​​​



  2. @Override  
  3. public boolean isViewFromObject(View arg0, Object arg1) {  
  4.     // TODO Auto-generated method stub  
  5.     return arg0 == arg1;  
  6. }  

isViewFromObject():对于这个函数就先不做解说，大家眼下先知道它要这样重写即可了