Android之ViewPager循环Demo

ViewPager是谷歌官方提供的兼容低版本安卓设备的软件包,里面包含了只有在安卓3.0以上可以使用的api。Viewpager现在也算是标配了,如果一个App没有用到ViewPager感觉还是比较罕见的,导航和页面菜单常用的功能,ViewPager与LisstView类似,ListView经常会用到BaseAdapter,ViewPager则继承的是PagerAdapter,关于简单的使用可以去官网可以http://developer.android.com/reference/android/support/v4/view/ViewPager.html当做参考了解一下,开始正题吧:

基础布局

看下效果图吧,网上好多都是放美女的,我还是简单点就放个TextView吧:

Android之ViewPager循环Demo

activity_main.xml

<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:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.example.googleviewpager.MainActivity" >



 <android.support.v4.view.ViewPager   

        android:id="@+id/viewpager"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_gravity="center" />



</RelativeLayout>

 需要切换的三个布局文件,one.xml,two.xml,three.xml,one.xml的代码,其他两个类似就不贴代码了:

<?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:orientation="vertical" 

    >

    

    <TextView 

        android:text="周永康被开"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"/>



</LinearLayout>

Demo实现

onCreate中的代码,其实分别加载了三个View,其中第一个和最后一个加载了一个空的View,主要是为了能够左右循环:

setContentView(R.layout.activity_main);

		LayoutInflater inflater=getLayoutInflater();

		viewPager=(ViewPager) findViewById(R.id.viewpager);

		view1=inflater.inflate(R.layout.one,null);

		view1.setBackgroundColor(Color.RED);

		view2=inflater.inflate(R.layout.two,null);

		view2.setBackgroundColor(Color.BLACK);

		view3=inflater.inflate(R.layout.three,null);

		view3.setBackgroundColor(Color.BLUE);

		viewList=new ArrayList<View>();

		viewList.add(new View(this));

		viewList.add(view1);

		viewList.add(view2);

		viewList.add(view3);

		viewList.add(new View(this));

		viewPager.setAdapter(new MyViewPagerAdapter(viewList));

		viewPager.setCurrentItem(1);

 自定义的MyViewPagerAdapter:

private class MyViewPagerAdapter extends PagerAdapter

	{

		@Override

		public void destroyItem(ViewGroup container, int position, Object object) {

			// TODO Auto-generated method stub

			container.removeView(myList.get(position));

		}

		@Override

		public Object instantiateItem(ViewGroup container, int position) {

			// TODO Auto-generated method stub

			container.addView(myList.get(position), 0);

	          return myList.get(position);

		}



		private List<View> myList;



		public   MyViewPagerAdapter(List<View> list) {

			myList=list;

		}



		@Override

		public int getCount() {

			// TODO Auto-generated method stub

			return myList.size();

		}



		@Override

		public boolean isViewFromObject(View arg0, Object arg1) {

			// TODO Auto-generated method stub

			  return arg0==(arg1);

		}



		

		

	}

  上面写完之后还是需要设置一下页面setOnPageChangeListener的事件,循环的重点就是切换到一个空的View时将页面替换掉就可以:

viewPager.setOnPageChangeListener(new OnPageChangeListener() {

			

			@Override

			public void onPageSelected(int arg0) {

				// TODO Auto-generated method stub

				 System.out.println("onPageSelected = " + arg0);

                 if(arg0 == 0)

                   viewPager.setCurrentItem(viewList.size()-2);

                 else if(arg0 == viewList.size() - 1)

                   viewPager.setCurrentItem(1);

			}

			

			@Override

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

				// TODO Auto-generated method stub

				

			}

			

			@Override

			public void onPageScrollStateChanged(int arg0) {

				// TODO Auto-generated method stub

				

			}

		});

  最后看一张切换中的效果吧:

Android之ViewPager循环Demo

Demo比较简单,不过对于入门应该是足够了~

 

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