android ViewPager 例子

今天用到viewpager，要实现多view动画切换。自己动手做了一个。

先上效果图，只是很简单的例子。

步骤：1、在main布局文件里添加viewPager布局

<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"
    >

    <LinearLayout
        android:id="@+id/top_ly"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/textView1"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="#999999"
            android:gravity="center"
            android:text="页面1"
            android:textColor="#222222"
            />
        <TextView
            android:id="@+id/textView2"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="#999999"
            android:gravity="center"
            android:text="页面2"
            android:textColor="#222222"
            />
        <TextView
            android:id="@+id/textView3"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="50dp"
            android:background="#999999"
            android:gravity="center"
            android:text="页面3"
            android:textColor="#222222"
            />
    </LinearLayout>

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

    <android.support.v4.view.ViewPager
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/cursor"
        android:layout_gravity="center"
        />

</RelativeLayout>

（可能需要导入jar包。下载地址：android-support-v4.jar）

再创建3个layout用于填充在ViewPager。我这里就是一个textview而已。

2、viewPager需要一个pagerAdapter的子类。

package com.away.viewpager;

import java.util.List;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;

public class ViewPagerAdapter extends PagerAdapter {

	List<View> viewLists;

    public ViewPagerAdapter(List<View> lists)
    {
        viewLists = lists;
    }

    //获得size
    @Override
    public int getCount() {
        return viewLists.size();
    }

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

    //销毁Item
    @Override
    public void destroyItem(View view, int position, Object object)
    {
        ((ViewPager) view).removeView(viewLists.get(position));
    }

    //实例化Item
    @Override
    public Object instantiateItem(View view, int position)
    {
        ((ViewPager) view).addView(viewLists.get(position), 0);
        return viewLists.get(position);
    }
}

3、最后mainActivity，主要写了左右滑动切换页面，还有一个小图片随页面切换位移的动画效果。

package com.away.viewpager;

import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.util.DisplayMetrics;
import android.view.Menu;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

	private ViewPager viewPager;
	private ImageView imageView;
	private List<View> lists = new ArrayList<View>();
	private ViewPagerAdapter adapter;
	private Bitmap cursor;
	private int offSet;
	private int currentItem;
	private Matrix matrix = new Matrix();
	private int bmWidth;
	private Animation animation;
	private TextView textView1;
	private TextView textView2;
	private TextView textView3;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		imageView = (ImageView) findViewById(R.id.cursor);
		textView1 = (TextView) findViewById(R.id.textView1);
		textView2 = (TextView) findViewById(R.id.textView2);
		textView3 = (TextView) findViewById(R.id.textView3);

		lists.add(getLayoutInflater().inflate(R.layout.layout1, null));
		lists.add(getLayoutInflater().inflate(R.layout.layout2, null));
		lists.add(getLayoutInflater().inflate(R.layout.layout3, null));

		initeCursor();

		adapter = new ViewPagerAdapter(lists);

		viewPager = (ViewPager) findViewById(R.id.viewPager);
		viewPager.setAdapter(adapter);
		viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

			// 当滑动式，顶部的imageView是通过animation缓慢的滑动
			@Override
			public void onPageSelected(int arg0) {
				switch (arg0) {
				case 0:
					if (currentItem == 1) {
						animation = new TranslateAnimation(
								offSet * 2 + bmWidth, 0, 0, 0);
					} else if (currentItem == 2) {
						animation = new TranslateAnimation(offSet * 4 + 2
								* bmWidth, 0, 0, 0);
					}
					break;
				case 1:
					if (currentItem == 0) {
						animation = new TranslateAnimation(0, offSet * 2
								+ bmWidth, 0, 0);
					} else if (currentItem == 2) {
						animation = new TranslateAnimation(4 * offSet + 2
								* bmWidth, offSet * 2 + bmWidth, 0, 0);
					}
					break;
				case 2:
					if (currentItem == 0) {
						animation = new TranslateAnimation(0, 4 * offSet + 2
								* bmWidth, 0, 0);
					} else if (currentItem == 1) {
						animation = new TranslateAnimation(
								offSet * 2 + bmWidth, 4 * offSet + 2 * bmWidth,
								0, 0);
					}
				}
				currentItem = arg0;
				animation.setDuration(150); // 光标滑动速度
				animation.setFillAfter(true);
				imageView.startAnimation(animation);
			}

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

			}
			@Override
			public void onPageScrollStateChanged(int arg0) {

			}
		});

		textView1.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				viewPager.setCurrentItem(0);
			}
		});

		textView2.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				viewPager.setCurrentItem(1);
			}
		});

		textView3.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				viewPager.setCurrentItem(2);
			}
		});
	}

	private void initeCursor() {
		cursor = BitmapFactory.decodeResource(getResources(), R.drawable.cursor);
		bmWidth = cursor.getWidth();

		DisplayMetrics dm;
		dm = getResources().getDisplayMetrics();

		offSet = (dm.widthPixels - 3 * bmWidth) / 6;
		matrix.setTranslate(offSet, 0);
		imageView.setImageMatrix(matrix); // 需要iamgeView的scaleType为matrix
		currentItem = 0;
	}

	@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;
	}
}

最后附上光标图。