【原创】android ViewPager控件的使用

android4.0有个控件，就是viewpager，用来实现左右滑动效果的。我们具体来看看是如何使用的。
首先看一下效果图

3个tab，每个tab有个layout，滑动的时候指示滑动条跟着走（当然，我觉得这个滑动条可以用三张图片来实现，更简单点）。
具体的我们看代码吧，主页xml就是实现上面三个tabbar，滑动条和一个viewpager控件，如下：

<?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:orientation="vertical" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="fill_parent"
        android:layout_height="100.0dip"
        android:background="#FFFFFF" >

        <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="页卡1"
            android:textColor="#000000"
            android:textSize="22.0dip" />

        <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="页卡2"
            android:textColor="#000000"
            android:textSize="22.0dip" />

        <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="页卡3"
            android:textColor="#000000"
            android:textSize="22.0dip" />
    </LinearLayout>

    <ImageView
        android:id="@+id/cursor"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:scaleType="matrix"
        android:src="@drawable/slide" />

    <android.support.v4.view.ViewPager
        android:id="@+id/vPager"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_weight="1.0"
        android:background="#000000"
        android:flipInterval="30"
        android:persistentDrawingCache="animation" />

</LinearLayout>

然后主要是看代码里面怎么用的，viewpager需要一个adapter来适配里面的每个layout。

public class ViewPageDemoActivity extends Activity {
	private ViewPager mPager;// 页卡内容
	private List<View> listViews; // Tab页面列表
	private ImageView cursor;// 动画图片
	private TextView t1, t2, t3;// 页卡头标
	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
	MyPagerAdapter adapter;
	LayoutInflater mInflater;

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		Log.i("Viewpage","--onCreate--");
		initImageView();
		initTextView();
		initPageView();
		
	}

	private void initPageView() {
		mInflater = getLayoutInflater();
		listViews = new ArrayList<View>();
		listViews.add(mInflater.inflate(R.layout.item1, null));
		listViews.add(mInflater.inflate(R.layout.item2, null));
		listViews.add(mInflater.inflate(R.layout.item3, null));
		adapter = new MyPagerAdapter(listViews);
		mPager = (ViewPager) findViewById(R.id.vPager);
		mPager.setAdapter(adapter);
		mPager.setCurrentItem(0);
		mPager.setOnPageChangeListener(new MyOnPageChangeListener());
	}

	private void initTextView() {
		t1 = (TextView) findViewById(R.id.text1);
		t2 = (TextView) findViewById(R.id.text2);
		t3 = (TextView) findViewById(R.id.text3);
		t1.setOnClickListener(new MyOnClickListener(0));
		t2.setOnClickListener(new MyOnClickListener(1));
		t3.setOnClickListener(new MyOnClickListener(2));
	}

	private void initImageView() {
		cursor = (ImageView) findViewById(R.id.cursor);
		bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.slide)
				.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);
		cursor.setImageMatrix(matrix);// 设置动画初始位置
	}

	private class MyOnClickListener implements View.OnClickListener {
		private int index = 0;

		public MyOnClickListener(int i) {
			index = i;
		}

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			mPager.setCurrentItem(index);
		}
	}

	public class MyPagerAdapter extends PagerAdapter {
		public List<View> mListViews;

		public MyPagerAdapter(List<View> mListViews) {
			this.mListViews = mListViews;
		}

		public void destroyItem(View arg0, int arg1, Object arg2) {
			((ViewPager) arg0).removeView(mListViews.get(arg1));
		}

		public void finishUpdate(View arg0) {
		}

		@Override
		public int getCount() {
			return mListViews.size();
		}

		@Override
		public Object instantiateItem(View arg0, int arg1) {
			((ViewPager) arg0).addView(mListViews.get(arg1), 0);
			return mListViews.get(arg1);
		}

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

		@Override
		public void restoreState(Parcelable arg0, ClassLoader arg1) {
		}

		@Override
		public Parcelable saveState() {
			return null;
		}

		@Override
		public void startUpdate(View arg0) {
		}
	}

	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

		@Override
		public void onPageSelected(int arg0) {
			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;
			}
			currIndex = arg0;
			animation.setFillAfter(true);// True:图片停在动画结束位置
			animation.setDuration(300);
			cursor.startAnimation(animation);
		}

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

		@Override
		public void onPageScrollStateChanged(int arg0) {
		}
	}
}

当然，你需要为每个tab对应一个layout，就想上面的item1，item2，item3一样。
这样就能实现左右滑动的一个效果了。

顺便说一下，viewpager刚开始推出，还没加入到正式的sdk，需要一个额外的jar包，运行工程的时候导入一下jar包就好了。
源码见附件。