ListView下拉回弹刷新

   现在QQ空间和新浪微博ListView下拉刷新做的比较炫，正好公司也有这样的需求，实现起来还是相对简单的。关键是要自定义一个ListView头部（初始化的时候里面的控件是不可见的），然后在点击、拖动、松开的时候触发事件，显示ListView头，计算出拖拽的距离，跟ListView头的高度做比较，以此来显示对应的ListView头里的控件（下拉图标、提示文字、圆形进度条等）。好了，下面贴出效果图：

 

好，开始上代码，先是布局文件main.xml，没什么好说的：

<?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"    android:background="@color/mainColor" >        <!-- 这里是自定义的ListView -->    <com.focustech.android.CustomListView        android:id="@+id/list"        android:layout_width="fill_parent"        android:layout_height="wrap_content"    /></LinearLayout>

ListView头布局head.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="match_parent"    android:orientation="vertical" >    <RelativeLayout        android:id="@+id/head_contentLayout"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:paddingLeft="30dp" >        <FrameLayout            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_alignParentLeft="true"            android:layout_centerVertical="true" >            <ImageView                android:id="@+id/head_arrowImageView"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_gravity="center"                android:src="@drawable/ic_pulltorefresh_arrow" />            <ProgressBar                android:id="@+id/head_progressBar"                style="?android:attr/progressBarStyleSmall"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:layout_gravity="center"                android:visibility="gone" />        </FrameLayout>        <LinearLayout            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_centerHorizontal="true"            android:gravity="center_horizontal"            android:orientation="vertical" >            <TextView                android:id="@+id/head_tipsTextView"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="下拉可以刷新"                android:textColor="#ffffff"                android:textSize="20sp" />            <TextView                android:id="@+id/head_lastUpdatedTextView"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="最近更新"                android:textColor="#cc6600"                android:textSize="10sp" />                    </LinearLayout>    </RelativeLayout></LinearLayout>

ListView item项布局listview_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="match_parent"    android:orientation="vertical" >     <ImageView        android:id="@+id/imageView"         android:layout_width="wrap_content"       android:layout_height="wrap_content"         android:src="@drawable/pretty_girl"    />     <TextView        android:id="@+id/textview"        android:layout_width="wrap_content"        android:layout_height="wrap_content"    /></LinearLayout>

清单文件也贴出来吧，其实就是自动生成的，什么都不用改：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.focustech.android"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk android:minSdkVersion="14" />    <application        android:icon="@drawable/ic_launcher"        android:label="@string/app_name" >        <activity            android:label="@string/app_name"            android:name="com.focustech.android.MainActivity" >            <intent-filter >                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

此Demo的Activity：

package com.focustech.android;import android.app.Activity;import android.database.DataSetObserver;import android.graphics.Color;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ListAdapter;import android.widget.TextView;import com.focustech.android.CustomListView.OnRefreshListener;import com.focustech.android.R;public class MainActivity extends Activity {private ListAdapter adapter;int size = 10;public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);final CustomListView list = (CustomListView) findViewById(R.id.list);adapter = new ListAdapter() {public void unregisterDataSetObserver(DataSetObserver arg0) {}public void registerDataSetObserver(DataSetObserver arg0) {}public boolean isEmpty() {return false;}public boolean hasStableIds() {return false;}public int getViewTypeCount() {return 1;}public View getView(int position, View convertView, ViewGroup parent) {convertView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.listview_item, null);TextView mTextView = (TextView) convertView.findViewById(R.id.textview);mTextView.setText("pretty girl" + position);mTextView.setTextColor(Color.RED);return convertView;}public int getItemViewType(int arg0) {return arg0;}public long getItemId(int arg0) {return arg0;}public Object getItem(int arg0) {return null;}public int getCount() {return size;}@Overridepublic boolean isEnabled(int position) {return false;}@Overridepublic boolean areAllItemsEnabled() {return false;}};list.setAdapter(adapter);// 在list上注册自定义的监听器list.setonRefreshListener(new OnRefreshListener() {public void onRefresh() {new Thread(new Runnable() {public void run() {try {Thread.sleep(1000);} catch (Exception e) {}runOnUiThread(new Runnable() {public void run() {list.onRefreshComplete();}});size++;}}).start();}});}}

实现了OnScrollListener的自定义ListView：

package com.focustech.android;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.AbsListView.OnScrollListener;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.TextView;import com.focustech.android.R;public class CustomListView extends ListView implements OnScrollListener {// 松开刷新标志private final static int RELEASE_To_REFRESH = 0;// 下拉刷新标志private final static int PULL_To_REFRESH = 1;// 正在刷新标志private final static int REFRESHING = 2;// 刷新完成标志private final static int DONE = 3;private LayoutInflater inflater;private LinearLayout headView;private TextView tipsTextview;private TextView lastUpdatedTextView;private ImageView arrowImageView;private ProgressBar progressBar;// 用来设置箭头图标动画效果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 headContentWidth;private int headContentHeight;private int startY;private int firstItemIndex;private int state;private boolean isBack;public OnRefreshListener refreshListener;private final static String TAG = "Monitor Current Infomation";public CustomListView(Context context, AttributeSet attrs) {super(context, attrs);init(context);}private void init(Context context) {inflater = LayoutInflater.from(context);headView = (LinearLayout) inflater.inflate(R.layout.head, null);arrowImageView = (ImageView) headView.findViewById(R.id.head_arrowImageView);arrowImageView.setMinimumWidth(50);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);measureView(headView);headContentHeight = headView.getMeasuredHeight();headContentWidth = headView.getMeasuredWidth();headView.setPadding(0, -1 * headContentHeight, 0, 0);headView.invalidate();Log.v("size", "width:" + headContentWidth + " height:"+ headContentHeight);addHeaderView(headView);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(500);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(500);reverseAnimation.setFillAfter(true);}public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,int arg3) {firstItemIndex = firstVisiableItem;}public void onScrollStateChanged(AbsListView arg0, int arg1) {}public boolean onTouchEvent(MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:if (firstItemIndex == 0 && !isRecored) {startY = (int) event.getY();isRecored = true;Log.v(TAG, "记录按下时的位置");}break;case MotionEvent.ACTION_UP:if (state != REFRESHING) {if (state == DONE) {Log.v(TAG, "什么都不做");}if (state == PULL_To_REFRESH) {state = DONE;changeHeaderViewByState();Log.v(TAG, "由下拉刷新状态到刷新完成状态");}if (state == RELEASE_To_REFRESH) {state = REFRESHING;changeHeaderViewByState();onRefresh();Log.v(TAG, "由松开刷新状态，到刷新完成状态");}}isRecored = false;isBack = false;break;case MotionEvent.ACTION_MOVE:int tempY = (int) event.getY();if (!isRecored && firstItemIndex == 0) {Log.v(TAG, "记录拖拽时的位置");isRecored = true;startY = tempY;}if (state != REFRESHING && isRecored) {// 可以松开刷新了if (state == RELEASE_To_REFRESH) {// 往上推，推到屏幕足够掩盖head的程度，但还没有全部掩盖if ((tempY - startY < 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else if (tempY - startY <= 0) {state = DONE;changeHeaderViewByState();Log.v(TAG, "由松开刷新状态转变到done状态");}// 往下拉，或者还没有上推到屏幕顶部掩盖headelse {// 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) {// 下拉到可以进入RELEASE_TO_REFRESH的状态if (tempY - startY >= 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) {state = PULL_To_REFRESH;changeHeaderViewByState();}}// 更新headView的sizeif (state == PULL_To_REFRESH) {headView.setPadding(0, -1 * headContentHeight+ (tempY - startY), 0, 0);headView.invalidate();}// 更新headView的paddingTopif (state == RELEASE_To_REFRESH) {headView.setPadding(0, tempY - startY - headContentHeight,0, 0);headView.invalidate();}}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("松开可以刷新");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);if (isBack) {isBack = false;arrowImageView.clearAnimation();arrowImageView.startAnimation(reverseAnimation);tipsTextview.setText("下拉可以刷新");} else {tipsTextview.setText("下拉可以刷新");}Log.v(TAG, "当前状态，下拉刷新");break;case REFRESHING:headView.setPadding(0, 0, 0, 0);headView.invalidate();progressBar.setVisibility(View.VISIBLE);arrowImageView.clearAnimation();arrowImageView.setVisibility(View.GONE);tipsTextview.setText("正在刷新，请稍后...");lastUpdatedTextView.setVisibility(View.GONE);Log.v(TAG, "当前状态,正在刷新...");break;case DONE:headView.setPadding(0, -1 * headContentHeight, 0, 0);headView.invalidate();progressBar.setVisibility(View.GONE);arrowImageView.clearAnimation();// 此处更换图标arrowImageView.setImageResource(R.drawable.ic_pulltorefresh_arrow);tipsTextview.setText("下拉可以刷新");lastUpdatedTextView.setVisibility(View.VISIBLE);Log.v(TAG, "当前状态，done");break;}}public void setonRefreshListener(OnRefreshListener refreshListener) {this.refreshListener = refreshListener;}public interface OnRefreshListener {public void onRefresh();}public void onRefreshComplete() {state = DONE;lastUpdatedTextView.setText("最近更新:" + new Date().toLocaleString());changeHeaderViewByState();}private void onRefresh() {if (refreshListener != null) {refreshListener.onRefresh();}}// 此处是“估计”headView的width以及heightprivate void measureView(View child) {ViewGroup.LayoutParams p = child.getLayoutParams();if (p == 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);}}

收工，有不足的地方欢迎大家指正。