Listview下拉刷新数据

Android listview仿新浪微博下拉刷新例子，其实所有此功能最早是国外实现的，现在网上能看到的都是基于这个例子，只是有些细节不同。算法上确实比较巧妙，直得学习一下。

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.com.karl.list"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="4" />

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".MainActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>

main..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" >

<cn.com.karl.list.MyListView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/listView"
/>

</LinearLayout>

head.xml

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

<!-- ListView的头部 -->

<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ffffff"
>

<!-- 内容 -->
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/head_contentLayout"
android:paddingLeft="30dp"
>

<!-- 箭头图像、进度条 -->
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
>

<!-- 箭头 -->
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:src="@drawable/arrow_down"
android:id="@+id/head_arrowImageView"
/>

<!-- 进度条 -->
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="?android:attr/progressBarStyleSmall"
android:layout_gravity="center"
android:id="@+id/head_progressBar"

android:visibility="gone"
/>

</FrameLayout>

<!-- 提示、最近更新 -->
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:orientation="vertical"
android:gravity="center_horizontal"
>

<!-- 提示 -->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下拉刷新"
android:textSize="15dp"
android:id="@+id/head_tipsTextView"
/>

<!-- 最近更新 -->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/head_lastUpdatedTextView"
android:text="上次更新"
android:textSize="12dp"
/>

</LinearLayout>

</RelativeLayout>

</LinearLayout>

item.xml

<?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="wrap_content"
android:gravity="center_vertical"
android:background="#ffffff"
android:orientation="horizontal" >

<ImageView
android:id="@+id/imageView_item"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:src="@drawable/ic_launcher" />

<TextView
android:id="@+id/textView_item"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:text="TextView" />

</LinearLayout>

MainActivity.java

package cn.com.karl.list;

import java.util.LinkedList;

import cn.com.karl.list.MyListView.OnRefreshListener;

import android.app.Activity;
import android.content.res.Configuration;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MainActivity extends Activity
{

private LinkedList<String> data;
private BaseAdapter adapter;
private MyListView listView;

public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

// 取得屏幕尺寸大小
displayScreenSize();

data = new LinkedList<String>();
for(int i=0;i<10;i++)
{
data.add(String.valueOf(i));
}

listView = (MyListView) findViewById(R.id.listView);

adapter = new BaseAdapter()
{
public View getView(int position, View convertView, ViewGroup parent)
{
convertView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.item, null);
TextView textView = (TextView) convertView.findViewById(R.id.textView_item);
textView.setText(data.get(position));
return convertView;
}

public long getItemId(int position)
{
return position;
}

public Object getItem(int position)
{
return data.get(position);
}

public int getCount()
{
return data.size();
}
};

listView.setAdapter(adapter);

listView.setOnRefreshListener(new OnRefreshListener()
{
public void onRefresh()
{
RefreshTask rTask = new RefreshTask();
rTask.execute(1000);
}
});
}

// AsyncTask异步任务
class RefreshTask extends AsyncTask<Integer, Integer, String>
{
@Override
protected String doInBackground(Integer... params)
{
try
{
Thread.sleep(params[0]);
}
catch (Exception e)
{
e.printStackTrace();
}
// 在data最前添加数据
data.addFirst("刷新后的内容");
return null;
}

@Override
protected void onPostExecute(String result)
{
super.onPostExecute(result);
adapter.notifyDataSetChanged();
listView.onRefreshComplete();
}
}

// 取得屏幕尺寸大小
public void displayScreenSize()
{
// 屏幕方面切换时获得方向
if (this.getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE)
{
setTitle("landscape");
}

if (this.getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT)
{
setTitle("portrait");
}

// 获得屏幕大小1
WindowManager manager = getWindowManager();
int width = manager.getDefaultDisplay().getWidth();
int height = manager.getDefaultDisplay().getHeight();

Log.v("am10", "width: " + width + " height: " + height);

// 获得屏幕大小2
DisplayMetrics dMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dMetrics);
int screenWidth = dMetrics.widthPixels;
int screenHeight = dMetrics.heightPixels;

Log.v("am10", "screenWidth: " + screenWidth + " screenHeight: " + screenHeight);
}
}

MyListView.java

package cn.com.karl.list;

import java.text.SimpleDateFormat;
import java.util.Date;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.AbsListView.OnScrollListener;
//import android.widget.ProgressBar;
import android.widget.TextView;

public class MyListView extends ListView implements OnScrollListener
{
private static final String TAG = "am10";
private final static int RELEASE_To_REFRESH = 0;
private final static int PULL_To_REFRESH = 1;
private final static int REFRESHING = 2;
private final static int DONE = 3;
private final static int LOADING = 4;

// 实际的padding的距离与界面上偏移距离的比例
private final static int RATIO = 3;

private LayoutInflater inflater;
private LinearLayout headView;
private TextView tipsTextview;
private TextView lastUpdatedTextView;
private ImageView arrowImageView;
//private ProgressBar progressBar;

private RotateAnimation animation;
private RotateAnimation reverseAnimation;

// 用于保证startY的值在一个完整的touch事件中只被记录一次
private boolean isRecored;

private int startY;
private int firstItemIndex;

private int headContentWidth;
private int headContentHeight;

private int state;

private boolean isBack;

private OnRefreshListener refreshListener;

private boolean isRefreshable;

public MyListView(Context context)
{
super(context);
init(context);
}

public MyListView(Context context, AttributeSet attrs)
{
super(context, attrs);
init(context);
}

private void init(Context context)
{
//setCacheColorHint(context.getResources().getColor(R.color.transparent));
inflater = LayoutInflater.from(context);

headView = (LinearLayout) inflater.inflate(R.layout.head, null);

arrowImageView = (ImageView) headView.findViewById(R.id.head_arrowImageView);
arrowImageView.setMinimumWidth(70);
arrowImageView.setMinimumHeight(50);

//progressBar = (ProgressBar) headView.findViewById(R.id.head_progressBar);
tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);
lastUpdatedTextView = (TextView) headView.findViewById(R.id.head_lastUpdatedTextView);

// 估算headView的宽和高
measureView(headView);
headContentHeight = headView.getMeasuredHeight();
headContentWidth = headView.getMeasuredWidth();

headView.setPadding(0, -1 * headContentHeight, 0, 0);
headView.invalidate();

Log.v(TAG, "width:" + headContentWidth + " height:" + headContentHeight);

addHeaderView(headView, null, false);
setOnScrollListener(this);

animation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
animation.setInterpolator(new LinearInterpolator());
animation.setDuration(250);
animation.setFillAfter(true);

reverseAnimation = new RotateAnimation(-180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
reverseAnimation.setInterpolator(new LinearInterpolator());
reverseAnimation.setDuration(200);
reverseAnimation.setFillAfter(true);

state = DONE;
isRefreshable = false;
}

public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2, int arg3)
{
firstItemIndex = firstVisiableItem;
//Log.v(TAG, "firstItemIndex: "+firstItemIndex);
}

public void onScrollStateChanged(AbsListView arg0, int arg1)
{
}

public boolean onTouchEvent(MotionEvent event)
{
// Log.v(TAG, "isRefreshable: "+isRefreshable);
if (isRefreshable)
{
switch (event.getAction())
{
case MotionEvent.ACTION_DOWN:
if (firstItemIndex == 0 && !isRecored)
{
isRecored = true;

// 触摸屏幕的位置
startY = (int) event.getY();
Log.v(TAG, "在down时候记录当前位置" + " startY:"+startY);
}
break;

case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING)
{
if (state == DONE)
{
// 什么都不做
}

if (state == PULL_To_REFRESH)
{
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "由下拉刷新状态，到done状态");
}

if (state == RELEASE_To_REFRESH)
{
state = REFRESHING;
changeHeaderViewByState();
onRefresh();
Log.v(TAG, "由松开刷新状态，到done状态");
}
}

isRecored = false;
isBack = false;
break;

case MotionEvent.ACTION_MOVE:
int tempY = (int) event.getY();
//Log.v(TAG, "tempY: " + tempY);

/**
* 手指移动过程中tempY数据会不断变化,当滑动到firstItemIndex,即到达顶部,
* 需要记录手指所在屏幕的位置: startY = tempY ,后面作位置比较使用
*
* 如果手指继续向下推,tempY继续变化,当tempY-startY>0,即是需要显示header部分
*
* 此时需要更改状态：state = PULL_To_REFRESH
*/
if (!isRecored && firstItemIndex == 0)
{
isRecored = true;
startY = tempY;
Log.v(TAG, "在move时候记录下位置" + " startY:"+startY);
}

if (state != REFRESHING && isRecored && state != LOADING)
{
/**
* 保证在设置padding的过程中，当前的位置一直是在head，
* 否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动
*/

// 可以松手去刷新了
if (state == RELEASE_To_REFRESH)
{
setSelection(0);

// 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步
if (((tempY - startY) / RATIO < headContentHeight) && (tempY - startY) > 0)
{
state = PULL_To_REFRESH;
changeHeaderViewByState();
Log.v(TAG, "由松开刷新状态转变到下拉刷新状态");
}

// 一下子推到顶了,没有显示header部分时,应该恢复DONE状态,这里机率很小
else if (tempY - startY <= 0)
{
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "---由松开刷新状态转变到done状态");
}
else
{
// 往下拉了，或者还没有上推到屏幕顶部掩盖head的地步
// 不用进行特别的操作，只用更新paddingTop的值就行了
}
}

// 还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态
if (state == PULL_To_REFRESH)
{
setSelection(0);

/**
* 下拉到可以进入RELEASE_TO_REFRESH的状态
*
* 等于headContentHeight时,即是正好完全显示header部分
* 大于headContentHeight时,即是超出header部分更多
*
* 当header部分能够完全显示或者超出显示,
* 需要更改状态: state = RELEASE_To_REFRESH
*/
if ((tempY - startY) / RATIO >= headContentHeight)
{
state = RELEASE_To_REFRESH;
isBack = true;
changeHeaderViewByState();
Log.v(TAG, "由done或者下拉刷新状态转变到松开刷新");
}

// 上推到顶了,没有显示header部分时,应该恢复DONE状态
else if (tempY - startY <= 0)
{
state = DONE;
changeHeaderViewByState();
Log.v(TAG, "由done或者下拉刷新状态转变到done状态");
}
}

// done状态下
if (state == DONE)
{
if (tempY - startY > 0)
{
/**
* 手指移动过程中tempY数据会不断变化,当滑动到firstItemIndex,即到达顶部,
* 需要记录手指所在屏幕的位置: startY = tempY ,后面作位置比较使用
*
* 如果手指继续向下推,tempY继续变化,当tempY-startY>0,即是需要显示header部分
*
* 此时需要更改状态：state = PULL_To_REFRESH
*/
//Log.v(TAG, "----------------PULL_To_REFRESH " + (tempY - startY));
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
}

// 更新headView的paddingTop
if (state == PULL_To_REFRESH)
{
//Log.v(TAG, "----------------PULL_To_REFRESH2 " + (tempY - startY));
headView.setPadding(0, -1 * headContentHeight + (tempY - startY) / RATIO, 0, 0);
}

// 继续更新headView的paddingTop
if (state == RELEASE_To_REFRESH)
{
headView.setPadding(0, (tempY - startY) / RATIO - headContentHeight, 0, 0);
}
}
break;
}
}
return super.onTouchEvent(event);
}

// 当状态改变时候，调用该方法，以更新界面
private void changeHeaderViewByState()
{
switch (state)
{
case RELEASE_To_REFRESH:
arrowImageView.setVisibility(View.VISIBLE);
//progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);

arrowImageView.clearAnimation();
arrowImageView.startAnimation(animation);

tipsTextview.setText("松开刷新");

Log.v(TAG, "当前状态，松开刷新");
break;

case PULL_To_REFRESH:
//progressBar.setVisibility(View.GONE);
tipsTextview.setVisibility(View.VISIBLE);
lastUpdatedTextView.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.VISIBLE);

/**
*  是否向下滑回，是由RELEASE_To_REFRESH状态转变来的
*/
if (isBack)
{
isBack = false;
arrowImageView.clearAnimation();
arrowImageView.startAnimation(reverseAnimation);
tipsTextview.setText("下拉刷新");
//Log.v(TAG, "isBack: " + isBack);
}
else
{
tipsTextview.setText("下拉刷新");
//Log.v(TAG, "isBack: " + isBack);
}

Log.v(TAG, "当前状态，下拉刷新");
break;

case REFRESHING:
Log.v(TAG, "REFRESHING...");
headView.setPadding(0, 0, 0, 0);

//progressBar.setVisibility(View.VISIBLE);
arrowImageView.clearAnimation();
arrowImageView.setVisibility(View.GONE);
tipsTextview.setText("正在刷新...");
lastUpdatedTextView.setVisibility(View.VISIBLE);

Log.v(TAG, "当前状态,正在刷新...");
break;

case DONE:
headView.setPadding(0, -1 * headContentHeight, 0, 0);

//progressBar.setVisibility(View.GONE);
arrowImageView.clearAnimation();
arrowImageView.setImageResource(R.drawable.arrow_down);
tipsTextview.setText("下拉刷新");
lastUpdatedTextView.setVisibility(View.VISIBLE);

Log.v(TAG, "当前状态，done");
break;
}
}

public void setOnRefreshListener(OnRefreshListener refreshListener)
{
this.refreshListener = refreshListener;
isRefreshable = true;
}

public interface OnRefreshListener
{
public void onRefresh();
}

public void onRefreshComplete()
{
state = DONE;
SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日  HH:mm");
String date = format.format(new Date());
lastUpdatedTextView.setText("最近更新:" + date);
changeHeaderViewByState();
}

private void onRefresh()
{
if (refreshListener != null)
{
refreshListener.onRefresh();
}
}

// 此方法直接照搬自网络上的一个下拉刷新的demo，此处是“估计”headView的width以及height
private void measureView(View child)
{
ViewGroup.LayoutParams p = child.getLayoutParams();
if (p == null)
{
//Log.v(TAG, "LayoutParams is null.");
p = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.FILL_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT);
}

int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);
int lpHeight = p.height;
int childHeightSpec;

if (lpHeight > 0)
{
childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight, MeasureSpec.EXACTLY);
}
else
{
childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
}

child.measure(childWidthSpec, childHeightSpec);
}

public void setAdapter(BaseAdapter adapter)
{
SimpleDateFormat format=new SimpleDateFormat("yyyy年MM月dd日  HH:mm");
String date=format.format(new Date());
lastUpdatedTextView.setText("最近更新:" + date);
super.setAdapter(adapter);
}
}

这个例子忘记那里下载的，这里也尊重作者，注明并不是我本人写的。如果谁知道原作者资料请告知，在此添加。

我修改了一下代码，使用AsyncTask异步任务更新数据，还有添加和修改了一些注释。