Android-使用ViewPager实现高仿launcher拖动效果（转）

ViewPager是实现左右两个屏幕平滑地切换的一个类

使用ViewPager首先需要引入android-support-v4.jar这个jar包。具体ViewPager的用法



首先是layout下面的main.xml

<?xml version="1.0" encoding="utf-8"?>

<FrameLayout 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="fill_parent"

        android:layout_height="wrap_content" />
    <RelativeLayout

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:orientation="vertical" >
        <LinearLayout

            android:id="@+id/viewGroup"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content"

            android:layout_alignParentBottom="true"

            android:layout_marginBottom="30dp"

            android:gravity="center_horizontal"

            android:orientation="horizontal" >

        </LinearLayout>

    </RelativeLayout>
</FrameLayout>

接下来为每一个切换界面设置布局item1.xml

<?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" >
    <ImageView

        android:layout_width="fill_parent"

        android:layout_height="fill_parent"

        android:background="@drawable/guide01" >

    </ImageView>
</LinearLayout>

其他的几个界面布局和这个一样 ，就是修改下背景图片，所以不再复述，

最后是核心代码：

import java.util.ArrayList;

import android.app.Activity;

import android.os.Bundle;

import android.os.Parcelable;

import android.support.v4.view.PagerAdapter;

import android.support.v4.view.ViewPager;

import android.support.v4.view.ViewPager.OnPageChangeListener;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.view.ViewGroup.LayoutParams;

import android.view.Window;

import android.widget.ImageView;

public class MainActivity extends Activity {

ViewPager viewPager;

ArrayList<View> list;

ViewGroup main, group;

ImageView imageView;

ImageView[] imageViews;

@Override

public void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);

  this.requestWindowFeature(Window.FEATURE_NO_TITLE);

  LayoutInflater inflater = getLayoutInflater();

  list = new ArrayList<View>();

  list.add(inflater.inflate(R.layout.item1, null));

  list.add(inflater.inflate(R.layout.item2, null));

  list.add(inflater.inflate(R.layout.item3, null));

  list.add(inflater.inflate(R.layout.item4, null));

  list.add(inflater.inflate(R.layout.item5, null));

  imageViews = new ImageView[list.size()];

  ViewGroup main = (ViewGroup) inflater.inflate(R.layout.main, null);

  // group是R.layou.main中的负责包裹小圆点的LinearLayout.

  ViewGroup group = (ViewGroup) main.findViewById(R.id.viewGroup);

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

  for (int i = 0; i < list.size(); i++) {

   imageView = new ImageView(MainActivity.this);

   imageView.setLayoutParams(new LayoutParams(10,10));

   imageView.setPadding(10, 0, 10, 0);

   imageViews[i] = imageView;

   if (i == 0) {

    // 默认进入程序后第一张图片被选中;

    imageViews[i].setBackgroundResource(R.drawable.guide_dot_white);

   } else {

    imageViews[i].setBackgroundResource(R.drawable.guide_dot_black);

   }

   group.addView(imageView);

  }

  setContentView(main);

  viewPager.setAdapter(new MyAdapter());

  viewPager.setOnPageChangeListener(new MyListener());

}

class MyAdapter extends PagerAdapter {

  @Override

  public int getCount() {

   return list.size();

  }

  @Override

  public boolean isViewFromObject(View arg0, Object arg1) {

   return arg0 == arg1;

  }

  @Override

  public int getItemPosition(Object object) {

   // TODO Auto-generated method stub

   return super.getItemPosition(object);

  }

  @Override

  public void destroyItem(View arg0, int arg1, Object arg2) {

   // TODO Auto-generated method stub

   ((ViewPager) arg0).removeView(list.get(arg1));

  }

  @Override

  public Object instantiateItem(View arg0, int arg1) {

   // TODO Auto-generated method stub

   ((ViewPager) arg0).addView(list.get(arg1));

   return list.get(arg1);

  }

  @Override

  public void restoreState(Parcelable arg0, ClassLoader arg1) {

   // TODO Auto-generated method stub

  }

  @Override

  public Parcelable saveState() {

   // TODO Auto-generated method stub

   return null;

  }

  @Override

  public void startUpdate(View arg0) {

   // TODO Auto-generated method stub

  }

  @Override

  public void finishUpdate(View arg0) {

   // TODO Auto-generated method stub

  }

}

class MyListener implements OnPageChangeListener {

  @Override

  public void onPageScrollStateChanged(int arg0) {

   // TODO Auto-generated method stub

  }

  @Override

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

   // TODO Auto-generated method stub

  }

  @Override

  public void onPageSelected(int arg0) {

   for (int i = 0; i < imageViews.length; i++) {

    imageViews[arg0]

      .setBackgroundResource(R.drawable.guide_dot_white);

    if (arg0 != i) {

     imageViews[i]

       .setBackgroundResource(R.drawable.guide_dot_black);

    }

   }

  }

}

}