android listview 的弹性滑动简单demo 实现

　　弹性滑动的效果比较好看。但是在2.2以下版本中，android 本身没有实现，想要实现这中效果要自己去写
　　前几天在iteye上看见了一个博客给我很大的启示，于是自己动手实验了一下感觉还可以。在这里把我的源码给大家贴上让大家一起分享，希望大家也能提出更好的意见。废话不多说上源码：
　　1.自己些一个MyListview 继承listview 类：

package com.wljie;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.animation.TranslateAnimation;
import android.widget.ListView;
public class MyListView extends ListView {
private Context context;
private boolean outBound = false;
private int distance;
private int firstOut;
private static final String TAG = "wljie";
public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
this.context = context;
Log.d(TAG, "IN 1");
}
public MyListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.context = context;
Log.d(TAG, "IN 2");
}
public MyListView(Context context) {
super(context);
this.context = context;
Log.d(TAG, "IN 3");
}
GestureDetector gestureDetector = new GestureDetector(
new OnGestureListener() {
@Override
public boolean onSingleTapUp(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}
@Override
public void onShowPress(MotionEvent e) {
// TODO Auto-generated method stub
}
/**
* 手势滑动的时候触发
*/
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
Log.d(TAG, "ENTER onscroll");
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) {
// TODO Auto-generated method stub
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2,
float velocityX, float velocityY) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean onDown(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}
});
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
Log.d(TAG, "dispatchTouchEvent");
int act = event.getAction();
if ((act == MotionEvent.ACTION_UP || act == MotionEvent.ACTION_CANCEL)
&& outBound) {
outBound = false;
// scroll back
}
if (!gestureDetector.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);
}
}

　　2.在main.xml 中写入

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        android:id="@+id/LinearLayout01"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        xmlns:android="http://schemas.android.com/apk/res/android"
        >
        <com.wljie.MyListView
        android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:id="@+id/MyListView"/>
</LinearLayout>

　　3.创建一个my_listitem.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        android:layout_width="fill_parent"
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_height="wrap_content"
        android:id="@+id/MyListItem"
        android:paddingBottom="3dip"
        android:paddingLeft="10dip">
        <TextView
                android:layout_height="wrap_content"
                android:layout_width="fill_parent"
                android:id="@+id/ItemTitle"
                android:textSize="30dip">
        </TextView>
        <TextView
                android:layout_height="wrap_content"
                android:layout_width="fill_parent"
                android:id="@+id/ItemText">
        </TextView>
</LinearLayout>

　　4.在Main.java中进行下一步的显示

package com.wljie;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.animation.TranslateAnimation;
import android.widget.SimpleAdapter;
public class Main extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// 绑定XML中的ListView，作为Item的容器
MyListView list = (MyListView) findViewById(R.id.MyListView);
// 生成动态数组，并且转载数据
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
for (int i = 0; i < 30; i++) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("ItemTitle", "This is Title.....");
map.put("ItemText", "This is text.....");
mylist.add(map);
}
// 生成适配器，数组===》ListItem
SimpleAdapter mSchedule = new SimpleAdapter(this, // 没什么解释
mylist,// 数据来源
R.layout.my_listitem,// ListItem的XML实现
// 动态数组与ListItem对应的子项
new String[] { "ItemTitle", "ItemText" },
// ListItem的XML文件里面的两个TextView ID
new int[] { R.id.ItemTitle, R.id.ItemText });
// 添加并且显示
list.setAdapter(mSchedule);
}
}