Android ListView弹性效果的实现方法

关于在android中实现listview的弹性效果，有很多不同的方法，网上一搜，也有很多，下面贴出在项目中经常用到的两种实现listview弹性效果的方法（基本上拿来就可以用），供大家参考：

第一种比较简单，好容易理解，只是动态改变了listview在y轴上的可移动距离，代码如下：

import android.content.context; 
import android.util.attributeset; 
import android.util.displaymetrics; 
import android.widget.listview; 
/** 
 * 弹性listview。 
 * @author e 
 */ 
public class flexilistview extends listview{ 
  //初始可拉动y轴方向距离 
  private static final int max_y_overscroll_distance = 100; 
  //上下文环境 
  private context mcontext; 
  //实际可上下拉动y轴上的距离 
  private int mmaxyoverscrolldistance; 
   
  public flexilistview(context context){ 
    super(context); 
    mcontext = context; 
    initbouncelistview(); 
  } 
   
  public flexilistview(context context, attributeset attrs) { 
    super(context, attrs); 
    mcontext = context; 
    initbouncelistview(); 
  } 
   
  public flexilistview(context context, attributeset attrs, int defstyle) { 
    super(context, attrs, defstyle); 
    mcontext = context; 
    initbouncelistview(); 
  } 
   
  private void initbouncelistview(){ 
    final displaymetrics metrics = mcontext.getresources().getdisplaymetrics(); 
      final float density = metrics.density; 
    mmaxyoverscrolldistance = (int) (density * max_y_overscroll_distance); 
  } 
   
  @override 
  protected boolean overscrollby(int deltax, int deltay, int scrollx, int scrolly, int scrollrangex,  
      int scrollrangey, int maxoverscrollx, int maxoverscrolly, boolean istouchevent) {  
    //实现的本质就是在这里动态改变了maxoverscrolly的值 
    return super.overscrollby(deltax, deltay, scrollx, scrolly, scrollrangex, scrollrangey, maxoverscrollx, mmaxyoverscrolldistance, istouchevent);  
  } 
   
} 

第二种方法，结合了手势来实现listview的弹性效果,这里可以根据手势来进行更多的扩展,代码如下:

import android.content.context; 
import android.graphics.rect; 
import android.util.attributeset; 
import android.view.gesturedetector; 
import android.view.gesturedetector.ongesturelistener; 
import android.view.motionevent; 
import android.view.view; 
import android.view.animation.translateanimation; 
import android.widget.listview; 
/** 
 * 具有弹性效果的listview。主要是实现父类dispatchtouchevent方法和ongesturelistener中onscroll方法。 
 * @author e 
 */ 
public class flexiblelistview extends listview implements ongesturelistener{ 
   
  private context context = null; 
  private boolean outbound = false; 
  private int distance; 
  private int firstout; 
   
  public flexiblelistview(context context, attributeset attrs) { 
    super(context, attrs); 
    this.context = context; 
  } 
   
  public flexiblelistview(context context, attributeset attrs, int defstyle) { 
    super(context, attrs, defstyle); 
    this.context = context; 
  } 
   
  public flexiblelistview(context context) { 
    super(context); 
    this.context = context; 
  } 
   
  gesturedetector lisgesturedetector = new gesturedetector(context, this); 
   
  @override 
  public boolean dispatchtouchevent(motionevent event) { 
    int act = event.getaction(); 
    if ((act == motionevent.action_up || act == motionevent.action_cancel) 
    && outbound) { 
    outbound = false; 
    // scroll back 
    } 
    if (!lisgesturedetector.ontouchevent(event)) { 
      outbound = false; 
    } else { 
      outbound = true; 
    } 
    rect rect = new rect();  
    getlocalvisiblerect(rect);  
    translateanimation am = new translateanimation( 0, 0, -rect.top, 0);  
    am.setduration(300);  
    startanimation(am);  
    scrollto(0, 0); 
    return super.dispatchtouchevent(event); 
  } 
 
  @override 
  public boolean ondown(motionevent e) { 
    return false; 
  } 
 
  @override 
  public void onshowpress(motionevent e) { 
  } 
 
  @override 
  public boolean onsingletapup(motionevent e) { 
    return false; 
  } 
 
  @override 
  public boolean onscroll(motionevent e1, motionevent e2, float distancex, 
      float distancey) { 
    int firstpos = getfirstvisibleposition(); 
    int lastpos = getlastvisibleposition(); 
    int itemcount = getcount(); 
    // outbound top 
    if (outbound && firstpos != 0 && lastpos != (itemcount - 1)) { 
    scrollto(0, 0); 
    return false; 
    } 
    view firstview = getchildat(firstpos); 
    if (!outbound) 
    firstout = (int) e2.getrawy(); 
    if (firstview != null&& (outbound || (firstpos == 0 
      && firstview.gettop() == 0 && distancey < 0))) { 
    // record the length of each slide 
    distance = firstout - (int) e2.getrawy(); 
    scrollto(0, distance / 2); 
    return true; 
    } 
    // outbound bottom 
    return false; 
  } 
 
  @override 
  public void onlongpress(motionevent e) { 
  } 
 
  @override 
  public boolean onfling(motionevent e1, motionevent e2, float velocityx, 
      float velocityy) { 
    return false; 
  } 
} 

以上两种常用android listview弹性效果的实现方法，整理出来，希望对大家有所帮助！