android ListView下拉刷新之头布局的完成

package com.example.listviewf5;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ListView;

public class MyListView extends ListView {
private View v;
private int headHeight;// 头部的高度
private int downY;// 按下时候Y坐标

public MyListView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
initView(context);
}

public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
initView(context);
}

public MyListView(Context context) {
super(context);
// TODO Auto-generated constructor stub
initView(context);
}

/**
* 加载顶部布局文件
*
* @param context
*/
private void initView(Context context) {
// LayoutInflater in =LayoutInflater.from(context);
// v = in.inflate(R.layout.head,null);
v = View.inflate(context, R.layout.head, null);
this.addHeaderView(v);
v.measure(0, 0);// 通知系统测量宽高
headHeight = v.getMeasuredHeight();// 得到测量后的高度
v.setPadding(0, -headHeight, 0, 0);// 进行隐藏head,就是把paddingtop设置成负高度

}

@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
downY = (int) ev.getY();
break;
case MotionEvent.ACTION_MOVE:
int deltaY = (int) (ev.getY() - downY);//得到移动的距离
int currentHeight = -headHeight + deltaY;
//判断当前的距离是不是大于headHeight 并且显示的是第一个位置
if(currentHeight>-headHeight && getFirstVisiblePosition()==0){
v.setPadding(0, currentHeight, 0, 0);//展现头部
return true;//拦截事件不让listview处理
}
break;
case MotionEvent.ACTION_UP:
break;
}
return super.onTouchEvent(ev);
}

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingBottom="10dp"
android:paddingTop="10dp"
android:layout_gravity="center_horizontal" >

<LinearLayout
android:id="@+id/ll"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:gravity="center"
android:orientation="vertical" >

<TextView
android:id="@+id/head_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下拉可以刷新" />

<TextView
android:id="@+id/head_tvtime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="上次刷新时间" />
</LinearLayout>

<ImageView
android:id="@+id/head_img"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="20dp"
android:layout_toLeftOf="@+id/ll"
android:src="@drawable/ic_launcher" />

<ProgressBar
android:id="@+id/pb"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="20dp"
android:layout_toLeftOf="@+id/ll"
android:visibility="gone" />
</RelativeLayout>

</LinearLayout>

<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" >

<com.example.listviewf5.MyListView
android:id="@+id/lv"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="none"/>

</RelativeLayout>

package com.example.listviewf5;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class MainActivity extends Activity {
private MyListView lv;
private List<Map<String, Object>> list;
private SimpleAdapter sa;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (MyListView) findViewById(R.id.lv);
list = new ArrayList<Map<String,Object>>();
for (int i = 0; i <20; i++) {
Map<String, Object> map = new HashMap<String, Object>();
map.put("key1","神马都是浮云");
map.put("key2","heheda");
list.add(map);
}
sa = new SimpleAdapter(this, list,R.layout.item_lv, new String[]{"key1","key2"},new int[]{R.id.tv,R.id.tv2});
lv.setAdapter(sa);
}
}