模仿QQ空间的下拉更新的功能实现

 

首先看看布局

1.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" >    <EditText        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:drawableLeft="@drawable/write"        android:lines="1"        android:padding="5px"        android:singleLine="true"        android:text="写说说" />    <TabHost        android:id="@+id/tabhost"        android:background="@drawable/bg"        android:layout_width="match_parent"        android:layout_height="match_parent" >        <LinearLayout            android:id="@+id/linearLayout1"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:orientation="vertical" >            <TabWidget                android:id="@android:id/tabs"                android:layout_width="match_parent"                android:layout_height="wrap_content" >            </TabWidget>            <FrameLayout                android:id="@android:id/tabcontent"                android:layout_width="match_parent"                android:layout_height="match_parent" >                <LinearLayout                    android:id="@+id/tab1"                    android:layout_width="match_parent"                    android:layout_height="match_parent"                    >                    <com.wang.MyListView                        android:id="@+id/listView"                        android:layout_width="fill_parent"                        android:layout_height="fill_parent"                        />                </LinearLayout>                <LinearLayout                    android:id="@+id/tab2"                    android:layout_width="match_parent"                    android:layout_height="match_parent"                     >                </LinearLayout>                <LinearLayout                    android:id="@+id/tab3"                    android:layout_width="match_parent"                    android:layout_height="match_parent"                     >                </LinearLayout>            </FrameLayout>        </LinearLayout>    </TabHost></LinearLayout>

2.list的条目布局list_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:orientation="horizontal" >    <ImageView        android:id="@+id/imageView_item"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginLeft="5dp"        android:src="@drawable/icon" />    <TextView        android:id="@+id/textView_item"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginLeft="10dp"        android:textColor="#FFFFFF"        /></LinearLayout>

3, 刷新布局refresh.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="wrap_content" >    <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/down" />            <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:textSize="15dp" />            <TextView                android:id="@+id/head_lastUpdatedTextView"                android:layout_width="wrap_content"                android:layout_height="wrap_content"                android:text="上次更新时间："                android:textSize="12dp" />        </LinearLayout>    </RelativeLayout></LinearLayout>

4.看看主活动实现的过程PullrefreshDemoActivity.xml

package com.wang;import java.util.LinkedList;import com.wang.MyListView.OnRefreshListener;import android.app.Activity;import android.content.res.Resources;import android.os.AsyncTask;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.Window;import android.view.WindowManager;import android.widget.BaseAdapter;import android.widget.TabHost;import android.widget.TextView;public class PullrefreshDemoActivity extends Activity {private LinkedList<String> data;private BaseAdapter adapter;public void onCreate(Bundle savedInstanceState) {// 去除标题栏requestWindowFeature(Window.FEATURE_NO_TITLE);// 设置全屏，取消状态栏this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);super.onCreate(savedInstanceState);setContentView(R.layout.main); TabHost tabhost=(TabHost)findViewById(R.id.tabhost);        tabhost.setup();        tabhost.addTab(tabhost.newTabSpec("tab1").setIndicator("好友动态").setContent(R.id.tab1));                tabhost.addTab(tabhost.newTabSpec("tab2").setIndicator("我的动态").setContent(R.id.tab2));        tabhost.addTab(tabhost.newTabSpec("tab3").setIndicator("我的应用").setContent(R.id.tab3));data = new LinkedList<String>();for (int i = 30; i < 40; i++) {// 输出list——item上的数据data.add(String.valueOf("暑假第" + i + "天，我们一直很宅，想家ing ..."));}final MyListView listView = (MyListView) findViewById(R.id.listView);adapter = new BaseAdapter() {// 得到一个视图,显示在指定位置上的数据在数据集，可以创建一个视图从XML布局文件public View getView(int position, View convertView, ViewGroup parent) {// 上下文全局应用程序对象convertView = LayoutInflater.from(getApplicationContext()).inflate(R.layout.list_item, null);// 实例化组件TextView textView = (TextView) convertView.findViewById(R.id.textView_item);// 设置文本本内容textView.setText(data.get(position));return convertView;}// 得到行相关联id列表中指定的位置。public long getItemId(int position) {return position;}// 获得相关的数据项中的指定位置的数据集public Object getItem(int position) {return data.get(position);}// 获得项目在数据集适配器的个数。public int getCount() {return data.size();}};listView.setAdapter(adapter);listView.setonRefreshListener(new OnRefreshListener() {public void onRefresh() {new AsyncTask<Void, Void, Void>() {// ...b表示多个参数protected Void doInBackground(Void... params) {try {// Thread.sleep(1000);} catch (Exception e) {e.printStackTrace();}// 增加一条数据到list中data.addFirst("刷新后内容：每天都是新的一天！！！，親！要努力奋斗哦！！！");return null;}protected void onPostExecute(Void result) {adapter.notifyDataSetChanged();listView.onRefreshComplete();}}.execute(null);}});}}

5.接着是列表实现个过程MyListView.xml

package com.wang;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 = "listview";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 headContentWidth;private int headContentHeight;private int startY;private int firstItemIndex;private int state;private boolean isBack;private OnRefreshListener refreshListener;private boolean isRefreshable;public MyListView(Context context) {super(context);// 调用下面初始化的函数init(context);}public MyListView(Context context, AttributeSet attrs) {super(context, attrs);// 调用下面初始化的函数init(context);}private void init(Context context) {// 获得LayoutInflater从给定的上下文。inflater = LayoutInflater.from(context);// 实例化布局XML文件转换成相应的视图对象。headView = (LinearLayout) inflater.inflate(R.layout.refresh, null);arrowImageView = (ImageView) headView.findViewById(R.id.head_arrowImageView);// 设置最小宽度 和高度arrowImageView.setMinimumWidth(70);arrowImageView.setMinimumHeight(50);// 实例化布局XML文件转换成相应的视图对象。progressBar = (ProgressBar) headView.findViewById(R.id.head_progressBar);tipsTextview = (TextView) headView.findViewById(R.id.head_tipsTextView);lastUpdatedTextView = (TextView) headView.findViewById(R.id.head_lastUpdatedTextView);// 调用下拉刷新的方法measureView(headView);// d得到原始高度和宽度headContentHeight = headView.getMeasuredHeight();headContentWidth = headView.getMeasuredWidth();// 设置填充。视图可能添加的空间要求显示滚动条,这取决于风格和知名度的滚动条headView.setPadding(0, -1 * headContentHeight, 0, 0);headView.invalidate();// 标签用来识别一个日志消息的来源。标识类或活动日志调用发生Log.v("size", "width:" + headContentWidth + " height:"+ headContentHeight);// 添加一个固定视图出现在列表的顶部addHeaderView(headView, null, false);// 设置监听事件setOnScrollListener(this);// 动画效果实现下拉和松开时候图片的 180度 旋转 注意0, -180,和他是有区别的 -180, 0,animation = new RotateAnimation(0, -180,RotateAnimation.RELATIVE_TO_SELF, 0.5f,RotateAnimation.RELATIVE_TO_SELF, 0.5f);// 设置加速度曲线为这个动画。默认值为一个线性插值。animation.setInterpolator(new LinearInterpolator());animation.setDuration(300);// 如果fillAfter是真的,转换,该动画执行完成时将会持续下去animation.setFillAfter(true);reverseAnimation = new RotateAnimation(-180, 0,RotateAnimation.RELATIVE_TO_SELF, 0.5f,RotateAnimation.RELATIVE_TO_SELF, 0.5f);// 设置加速度曲线为这个动画。默认值为一个线性插值。reverseAnimation.setInterpolator(new LinearInterpolator());reverseAnimation.setDuration(300);// 如果fillAfter是真的,转换,该动画执行完成时将会持续下去reverseAnimation.setFillAfter(true);// 设置状态state = DONE;// 设置不可刷新状态isRefreshable = false;}// 回调方法时要调用的列表或网格已经滚动。这将完成之后调用的滚动方法public void onScroll(AbsListView arg0, int firstVisiableItem, int arg2,int arg3) {firstItemIndex = firstVisiableItem;}/* * 回调方法调用而列表视图或网格视图被滚动。 如果这个视图被滚动,将调用此方法在接下来的一局画卷的呈现 * */public void onScrollStateChanged(AbsListView arg0, int arg1) {}// 触摸事件监听public boolean onTouchEvent(MotionEvent event) {// 判断是否可以刷新if (isRefreshable) {// 根据动作相应不同的方法switch (event.getAction()) {// 当按住屏幕向下拉屏幕的时候case MotionEvent.ACTION_DOWN:if (firstItemIndex == 0 && !isRecored) {isRecored = true;startY = (int) event.getY();Log.v(TAG, "在下拉的时候记录当前位置‘");}break;// 当按住屏幕向上松屏幕的时候case MotionEvent.ACTION_UP:if (state != REFRESHING && state != LOADING) {if (state == DONE) {}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;// 当按住屏幕移动时候case MotionEvent.ACTION_MOVE:int tempY = (int) event.getY();if (!isRecored && firstItemIndex == 0) {Log.v(TAG, "在move时候记录下位置");isRecored = true;startY = tempY;}if (state != REFRESHING && isRecored && state != LOADING) {/*** * ， 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else if (tempY - startY <= 0) {state = DONE;// 调用改变时候的方法，更新UIchangeHeaderViewByState();Log.v(TAG, "由松开刷新状态转变到done状态");} else {}}// 还没有到达显示松开刷新的时候if (state == PULL_To_REFRESH) {setSelection(0);// 下拉到可以进入RELEASE_TO_REFRESH的状态if ((tempY - startY) / RATIO >= headContentHeight) {state = RELEASE_To_REFRESH;isBack = true;// 调用改变时候的方法，更新UIchangeHeaderViewByState();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;// 调用改变时候的方法，更新UIchangeHeaderViewByState();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;// 调用改变时候的方法，更新UIchangeHeaderViewByState();}}// 更新headView的sizeif (state == PULL_To_REFRESH) {headView.setPadding(0, -1 * headContentHeight+ (tempY - startY) / RATIO, 0, 0);}// 更新headView的paddingTopif (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() {// 根据当前的状态进行判断switch (state) {// 下拉时候，松开既可刷新case RELEASE_To_REFRESH:// 设置视图 VISIBLE 可见 ，GONE 不可见arrowImageView.setVisibility(View.VISIBLE);progressBar.setVisibility(View.GONE);tipsTextview.setVisibility(View.VISIBLE);lastUpdatedTextView.setVisibility(View.VISIBLE);// 现在开始指定的动画。arrowImageView.clearAnimation();arrowImageView.startAnimation(animation);tipsTextview.setText("松开既可刷新");Log.v(TAG, "当前状态，松开即可刷新");break;// 开始时候，下拉刷新case PULL_To_REFRESH:// 设置视图 VISIBLE 可见 ，GONE 不可见progressBar.setVisibility(View.GONE);tipsTextview.setVisibility(View.VISIBLE);lastUpdatedTextView.setVisibility(View.VISIBLE);// 现在开始指定的动画。arrowImageView.clearAnimation();arrowImageView.setVisibility(View.VISIBLE);if (isBack) {isBack = false;// 现在开始指定的动画。arrowImageView.clearAnimation();arrowImageView.startAnimation(reverseAnimation);tipsTextview.setText("下拉刷新");} else {tipsTextview.setText("下拉刷新");}Log.v(TAG, "当前状态，下拉刷新");break;case REFRESHING:headView.setPadding(0, 0, 0, 0);// 设置视图 VISIBLE 可见 ，GONE 不可见progressBar.setVisibility(View.VISIBLE);// 现在开始指定的动画。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:// 设置填充。视图可能添加的空间要求显示滚动条headView.setPadding(0, -1 * headContentHeight, 0, 0);// 设置视图 VISIBLE 可见 ，GONE 不可见progressBar.setVisibility(View.GONE);// 现在开始指定的动画。arrowImageView.clearAnimation();arrowImageView.setImageResource(R.drawable.down);tipsTextview.setText("下拉刷新");lastUpdatedTextView.setVisibility(View.VISIBLE);Log.v(TAG, "当前状态");break;}}public void setonRefreshListener(OnRefreshListener refreshListener) {this.refreshListener = refreshListener;isRefreshable = true;}public interface OnRefreshListener {public void onRefresh();}// 设置更新时间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();}}// 下拉刷新的private void measureView(View child) {// v这组布局参数宽度和高度ViewGroup.LayoutParams p = child.getLayoutParams();if (p == null) {// 创建一个新组布局参数指定的宽度(填充)和高度（包裹）。p = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);}// d得到childWidthSpec(高度或宽度)的子视图int childWidthSpec = ViewGroup.getChildMeasureSpec(0, 0 + 0, p.width);int lpHeight = p.height;int childHeightSpec;if (lpHeight > 0) {// 创建一个测量规范基于所提供的大小和模式childHeightSpec = MeasureSpec.makeMeasureSpec(lpHeight,MeasureSpec.EXACTLY);} else {childHeightSpec = MeasureSpec.makeMeasureSpec(0,MeasureSpec.UNSPECIFIED);}// 找出一个视图应该多大。父供应约束信息在宽度和高度参数child.measure(childWidthSpec, childHeightSpec);}public void setAdapter(BaseAdapter adapter) {// 设置最近刷新的时间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);}}

6.接着就可以看到运行结果了，运行结果如下：