Android实现广告图片轮播效果

本文实例介绍了Android广告轮播图效果实现方法，分享给大家供大家参考，具体内容如下

首先看下一下布局文件：

<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"
  tools:context=".MainActivity" >
  <!-- 广告条的使用 -->
  <com.xuliugen.viewpager.MyViewPagerTransformerAnim
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="200dp" />
  <!-- 广告条下边的文字 -->
  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignBottom="@id/viewpager"
    android:background="#33000000"
    android:orientation="vertical" >
    <TextView
      android:id="@+id/image_desc"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:gravity="center"
      android:text="@string/app_name"
      android:textColor="@android:color/white"
      android:textSize="16sp" />
    <LinearLayout
      android:id="@+id/point_group"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="center_horizontal"
      android:layout_marginBottom="5dp"
      android:orientation="horizontal" >
    </LinearLayout>
  </LinearLayout>
</RelativeLayout>

 

效果很简单，从布局文件中我们看到使用了一个自定义的ViewPager动画，代码如下：

package com.xuliugen.viewpager;
import java.util.HashMap;
import java.util.Map;
import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.View;
import com.nineoldandroids.view.ViewHelper;

public class MyViewPagerTransformerAnim extends ViewPager {
  private View mLeft;
  private View mRight;
  private float mTrans;
  private float mScale;
  private static final float MIN_SCALE = 0.6f;
  private Map<Integer, View> mChildren = new HashMap<Integer, View>();
  
  public MyViewPagerTransformerAnim(Context context, AttributeSet attrs) {
    super(context, attrs);
  }
  public MyViewPagerTransformerAnim(Context context) {
    super(context);
  }
  
  public void setViewForPosition(View view, int position) {
    mChildren.put(position, view);
  }
  
  public void removeViewFromPosition(Integer position) {
    mChildren.remove(position);
  }
  
  @Override
  protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Log.e("TAG", "position =" + position + ",offset = " + offset);
    mLeft = mChildren.get(position);
    mRight = mChildren.get(position + 1);
    animStack(mLeft, mRight, offset, offsetPixels);// 创建动画效果
    super.onPageScrolled(position, offset, offsetPixels);
  }
  private void animStack(View left, View right, float offset, int offsetPixels) {
    if (right != null) {
      // 从0-1页，offset:0`1
      mScale = (1 - MIN_SCALE) * offset + MIN_SCALE;
      mTrans = -getWidth() - getPageMargin() + offsetPixels;
      ViewHelper.setScaleX(right, mScale);
      ViewHelper.setScaleY(right, mScale);
      ViewHelper.setTranslationX(right, mTrans);
    }
    if (left != null) {
      left.bringToFront();
    }
  }
}

MainActivity.java

package com.xuliugen.viewpager;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
public class MainActivity extends Activity {
  private ViewPager viewPager;
  private LinearLayout pointGroup;
  private TextView iamgeDesc;
  // 图片资源ID
  private final int[] imageIds = { R.drawable.a, R.drawable.b, R.drawable.c,
      R.drawable.d, R.drawable.e };
  // 图片标题集合
  private final String[] imageDescriptions = { "巩俐不低俗，我就不能低俗",
      "扑树又回来啦！再唱经典老歌引万人大合唱", "揭秘北京电影如何升级", "乐视网TV版大派送", "热血屌丝的反杀" };
  private ArrayList<ImageView> imageList;
  
  protected int lastPosition;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    viewPager = (ViewPager) findViewById(R.id.viewpager);
    pointGroup = (LinearLayout) findViewById(R.id.point_group);
    iamgeDesc = (TextView) findViewById(R.id.image_desc);
    iamgeDesc.setText(imageDescriptions[0]);
    imageList = new ArrayList<ImageView>();
    for (int i = 0; i < imageIds.length; i++) {
      // 初始化图片资源
      ImageView image = new ImageView(this);
      image.setBackgroundResource(imageIds[i]);
      imageList.add(image);
      // 添加指示点
      ImageView point = new ImageView(this);
      LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
          LinearLayout.LayoutParams.WRAP_CONTENT,
          LinearLayout.LayoutParams.WRAP_CONTENT);
      params.rightMargin = 20;
      point.setLayoutParams(params);
      point.setBackgroundResource(R.drawable.point_bg);
      if (i == 0) {
        point.setEnabled(true);
      } else {
        point.setEnabled(false);
      }
      pointGroup.addView(point);
    }
    viewPager.setAdapter(new MyPagerAdapter());
    // viewPager.setCurrentItem(Integer.MAX_VALUE/2 -
    // (Integer.MAX_VALUE/2%imageList.size())) ;
    viewPager.setOnPageChangeListener(new OnPageChangeListener() {
      @Override
      
      public void onPageSelected(int position) {
        position = position % imageList.size();
        // 设置文字描述内容
        iamgeDesc.setText(imageDescriptions[position]);
        // 改变指示点的状态
        // 把当前点enbale 为true
        pointGroup.getChildAt(position).setEnabled(true);
        // 把上一个点设为false
        pointGroup.getChildAt(lastPosition).setEnabled(false);
        lastPosition = position;
      }
      @Override
      
      public void onPageScrolled(int position, float positionOffset,
          int positionOffsetPixels) {
      }
      @Override
      
      public void onPageScrollStateChanged(int state) {
      }
    });
    
    isRunning = true;
    // 设置图片的自动滑动
    handler.sendEmptyMessageDelayed(0, 3000);
  }
  
  private boolean isRunning = false;
  private Handler handler = new Handler() {
    public void handleMessage(android.os.Message msg) {
      // 让viewPager 滑动到下一页
      viewPager.setCurrentItem(viewPager.getCurrentItem() + 1);
      if (isRunning) {
        handler.sendEmptyMessageDelayed(0, 3000);
      }
    };
  };
  protected void onDestroy() {
    isRunning = false;
  };
  private class MyPagerAdapter extends PagerAdapter {
    @Override
    
    public int getCount() {
      return Integer.MAX_VALUE; // 使得图片可以循环
    }
    @Override
    
    public Object instantiateItem(ViewGroup container, int position) {
      // System.out.println("instantiateItem ::" + position);
      // 给 container 添加一个view
      container.addView(imageList.get(position % imageList.size()));
      // 返回一个和该view相对的object
      return imageList.get(position % imageList.size());
    }
    @Override
    
    public boolean isViewFromObject(View view, Object object) {
      if (view == object) {
        return true;
      } else {
        return false;
      }
    }
    @Override
    
    public void destroyItem(ViewGroup container, int position, Object object) {
      // System.out.println("destroyItem ::" + position);
      container.removeView((View) object);
      object = null;
    }
  }
}

另外我们看效果图可以看出，效果图下边的几个原点是变化的，所以我们需要一个selector，如下：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:drawable="@drawable/point_nomal" android:state_enabled="false"/>
  <item android:drawable="@drawable/point_focured" android:state_enabled="true"/>
</selector>

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