Android中实现下拉刷新
Android中实现下拉刷新
分类:Android 2012-03-23 15:43 1404人阅读 评论(1) 收藏 举报需求:项目中的消息列表界面要求实现类似sina微博的下拉刷新;
思路:一般的消息列表为ListView类型,将list加载到adapter中,再将adapter加载到ListView中,从而实现消息列表的展示。而下拉刷新要求给消息列表加一个头部,其中有图片(向上/向下箭头)和提示字样(下拉刷新/松开刷新),从而我们需要做的事情:1.需要做一个head.xm来实现头部的样式定义;2.需要自定义一个继承了ListView的MsgListView,在该类中将head加在MsgListView对象的头部;3.将原有的消息界面布局文件中的ListView改为cn.xd.microblogging.tools.MsgListView(包名.MsgListView);4.将原有的消息界面后台代码中创建的ListView对象改为MsgListView对象,注意消息界面Activity要继承ListActivity,并且实现其刷新监听。
说明:实现下拉刷新很简单,仅需要4个文件:MsgRcvListActivity.java(消息列表界面的后台文件,真正的刷新动作在这里完成,下拉刷新相关code下面列出),msgrcvlistactivity.xml(消息列表界面的前台文件,下拉刷新相关code下面列出),MsgListView.java(本文件拿来主义即可不用改,下拉刷新自定义的列表类,监听并执行下拉刷新、松开刷新、正在刷新、完成刷新等状态的改变,但真正的刷新动作不在这里完成,完整code下面列出),head.xml(本文件拿来主义即可不用改,下拉刷新的样式定义文件,包括向上、向下箭头,刷新状态提示等,完整code下面列出);
效果:
代码:
1.MsgRcvListActivity.java :
[java] view plain copy- publicclassMsgRcvListActivityextendsListActivity{//注意:要继承ListActivity
- …………//变量定义,略
- MsgListViewlist;
- @Override
- protectedvoidonCreate(BundlesavedInstanceState){
- super.onCreate(savedInstanceState);
- setContentView(R.layout.msgrcvlistactivity);
- list=(MsgListView)findViewById(android.R.id.list);//继承ListActivity,id要写成android.R.id.list,否则报异常
- …………//其他代码,略
- //刷新监听,此处实现真正刷新
- list.setonRefreshListener(newOnRefreshListener(){
- publicvoidonRefresh(){
- newAsyncTask<Void,Void,Void>(){
- protectedVoiddoInBackground(Void...params){
- try{
- Thread.sleep(1000);
- }catch(Exceptione){
- e.printStackTrace();
- }
- returnnull;
- }
- @Override
- protectedvoidonPostExecute(Voidresult){
- adapter.notifyDataSetChanged();
- newMsgLoad().execute();//刷新监听中,真正执行刷新动作
- list.onRefreshComplete();
- }
- }.execute(null);
- }
- });
- list.setItemsCanFocus(false);
- list.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
- }
- …………//其他代码,略
- publicclassMsgLoadextendsAsyncTask<Void,Void,List<MsgBean>>{
- …………//其他代码,略
- }
- }
2.msgrcvlistactivity.xml:
[html] view plain copy- <?xmlversion="1.0"encoding="utf-8"?>
- <RelativeLayout
- xmlns:android="http://schemas.android.com/apk/res/android"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- >
- <LinearLayoutandroid:orientation="vertical"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:background="#000000">
- //将ListView改为包名.自定义的列表类名,MsgListView.java代码见后,此代码不需改通用,下拉刷新相关即此处,其他无关
- <cn.xd.microblogging.tools.MsgListView
- android:id="@android:id/list"
- android:layout_height="wrap_content"
- android:layout_width="fill_parent"
- android:layout_weight="1.0"
- android:drawSelectorOnTop="false"
- android:scrollbars="vertical"
- android:fadingEdgeLength="0dip"
- android:divider="@drawable/line"
- android:dividerHeight="3.0dip"
- android:cacheColorHint="#00000000"
- android:paddingBottom="40dp"/>
- </LinearLayout>
- <LinearLayout
- android:id="@+id/msg_list_load"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <LinearLayoutandroid:id="@android:id/empty"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <include
- android:id="@android:id/empty"
- layout="@layout/empty_loading"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"/>
- </LinearLayout>
- </LinearLayout>
- </RelativeLayout>
3.MsgListView.java,拷进项目基本不需改:
[java] view plain copy- packagecn.xd.microblogging.tools;
- importjava.util.Date;
- importcn.xd.microblogging.R;
- importandroid.content.Context;
- importandroid.util.AttributeSet;
- importandroid.util.Log;
- importandroid.view.LayoutInflater;
- importandroid.view.MotionEvent;
- importandroid.view.View;
- importandroid.view.ViewGroup;
- importandroid.view.animation.LinearInterpolator;
- importandroid.view.animation.RotateAnimation;
- importandroid.widget.AbsListView;
- importandroid.widget.BaseAdapter;
- importandroid.widget.ImageView;
- importandroid.widget.LinearLayout;
- importandroid.widget.ListView;
- importandroid.widget.AbsListView.OnScrollListener;
- importandroid.widget.ProgressBar;
- importandroid.widget.TextView;
- /**
- *
- *自定义MsgListView,继承了ListView,
- *但填充了listview的头部,即下拉刷新样式,并实现其功能
- *@authoryanbo
- *
- */
- publicclassMsgListViewextendsListViewimplementsOnScrollListener{
- privatefinalstaticintRELEASE_To_REFRESH=0;
- privatefinalstaticintPULL_To_REFRESH=1;
- privatefinalstaticintREFRESHING=2;
- privatefinalstaticintDONE=3;
- privateLayoutInflaterinflater;
- privateLinearLayoutheadView;//头部
- privateTextViewtipsTextview;//下拉刷新
- privateTextViewlastUpdatedTextView;//最新更新
- privateImageViewarrowImageView;//箭头
- privateProgressBarprogressBar;//刷新进度条
- privateRotateAnimationanimation;//旋转特效刷新中箭头翻转向下变向上
- privateRotateAnimationreverseAnimation;
- //用于保证startY的值在一个完整的touch事件中只被记录一次
- privatebooleanisRecored;
- privateintheadContentWidth;//头部宽度
- privateintheadContentHeight;//头部高度
- privateintstartY;//高度起始位置,用来记录与头部距离
- privateintfirstItemIndex;//列表中首行索引,用来记录其与头部距离
- privateintstate;//下拉刷新中、松开刷新中、正在刷新中、完成刷新
- privatebooleanisBack;
- publicOnRefreshListenerrefreshListener;//刷新监听
- privatefinalstaticStringTAG="abc";
- publicMsgListView(Contextcontext,AttributeSetattrs){
- super(context,attrs);
- init(context);
- }
- privatevoidinit(Contextcontext){
- inflater=LayoutInflater.from(context);
- headView=(LinearLayout)inflater.inflate(R.layout.head,null);//listview拼接headview
- arrowImageView=(ImageView)headView
- .findViewById(R.id.head_arrowImageView);//headview中各view
- arrowImageView.setMinimumWidth(50);
- arrowImageView.setMinimumHeight(50);
- progressBar=(ProgressBar)headView
- .findViewById(R.id.head_progressBar);//headview中各view
- tipsTextview=(TextView)headView.findViewById(R.id.head_tipsTextView);//headview中各view
- lastUpdatedTextView=(TextView)headView
- .findViewById(R.id.head_lastUpdatedTextView);//headview中各view
- measureView(headView);
- headContentHeight=headView.getMeasuredHeight();//头部高度
- headContentWidth=headView.getMeasuredWidth();//头部宽度
- headView.setPadding(0,-1*headContentHeight,0,0);//setPadding(intleft,inttop,intright,intbottom)
- headView.invalidate();//Invalidatethewholeview
- Log.v("size","width:"+headContentWidth+"height:"
- +headContentHeight);
- addHeaderView(headView);//添加进headview
- setOnScrollListener(this);//滚动监听
- animation=newRotateAnimation(0,-180,
- RotateAnimation.RELATIVE_TO_SELF,0.5f,
- RotateAnimation.RELATIVE_TO_SELF,0.5f);
- animation.setInterpolator(newLinearInterpolator());
- animation.setDuration(250);
- animation.setFillAfter(true);//特效animation设置
- reverseAnimation=newRotateAnimation(-180,0,
- RotateAnimation.RELATIVE_TO_SELF,0.5f,
- RotateAnimation.RELATIVE_TO_SELF,0.5f);
- reverseAnimation.setInterpolator(newLinearInterpolator());
- reverseAnimation.setDuration(250);
- reverseAnimation.setFillAfter(true);//特效reverseAnimation设置
- }
- publicvoidonScroll(AbsListViewarg0,intfirstVisiableItem,intarg2,//滚动事件
- intarg3){
- firstItemIndex=firstVisiableItem;//得到首item索引
- }
- publicvoidonScrollStateChanged(AbsListViewarg0,intarg1){
- }
- publicbooleanonTouchEvent(MotionEventevent){//触摸事件
- switch(event.getAction()){
- caseMotionEvent.ACTION_DOWN://手按下对应下拉刷新状态
- if(firstItemIndex==0&&!isRecored){//如果首item索引为0,且尚未记录startY,则在下拉时记录之,并执行isRecored=true;
- startY=(int)event.getY();
- isRecored=true;
- Log.v(TAG,"在down时候记录当前位置‘");
- }
- break;
- caseMotionEvent.ACTION_UP://手松开对应松开刷新状态
- if(state!=REFRESHING){//手松开有4个状态:下拉刷新、松开刷新、正在刷新、完成刷新。如果当前不是正在刷新
- if(state==DONE){//如果当前是完成刷新,什么都不做
- }
- if(state==PULL_To_REFRESH){//如果当前是下拉刷新,状态设为完成刷新(意即下拉刷新中就松开了,实际未完成刷新),执行changeHeaderViewByState()
- state=DONE;
- changeHeaderViewByState();
- Log.v(TAG,"由下拉刷新状态,到done状态");
- }
- if(state==RELEASE_To_REFRESH){//如果当前是松开刷新,状态设为正在刷新(意即松开刷新中松开手,才是真正地刷新),执行changeHeaderViewByState()
- state=REFRESHING;
- changeHeaderViewByState();
- onRefresh();//真正刷新,所以执行onrefresh,执行后状态设为完成刷新
- Log.v(TAG,"由松开刷新状态,到done状态");
- }
- }
- isRecored=false;//手松开,则无论怎样,可以重新记录startY,因为只要手松开就认为一次刷新已完成
- isBack=false;
- break;
- caseMotionEvent.ACTION_MOVE://手拖动,拖动过程中不断地实时记录当前位置
- inttempY=(int)event.getY();
- if(!isRecored&&firstItemIndex==0){//如果首item索引为0,且尚未记录startY,则在拖动时记录之,并执行isRecored=true;
- Log.v(TAG,"在move时候记录下位置");
- isRecored=true;
- startY=tempY;
- }
- if(state!=REFRESHING&&isRecored){//如果状态不是正在刷新,且已记录startY:tempY为拖动过程中一直在变的高度,startY为拖动起始高度
- //可以松手去刷新了
- if(state==RELEASE_To_REFRESH){//如果状态是松开刷新
- //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<headContentHeight)//如果实时高度大于起始高度,且两者之差小于头部高度,则状态设为下拉刷新
- &&(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
- elseif(tempY-startY<=0){//如果实时高度小于等于起始高度了,则说明到顶了,状态设为完成刷新
- state=DONE;
- changeHeaderViewByState();
- Log.v(TAG,"由松开刷新状态转变到done状态");
- }
- //往下拉了,或者还没有上推到屏幕顶部掩盖head的地步
- else{//如果当前拖动过程中既没有到下拉刷新的地步,也没有到完成刷新(到顶)的地步,则保持松开刷新状态
- //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){//如果状态是下拉刷新
- //下拉到可以进入RELEASE_TO_REFRESH的状态
- if(tempY-startY>=headContentHeight){//如果实时高度与起始高度之差大于等于头部高度,则状态设为松开刷新
- 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
- elseif(tempY-startY<=0){//如果实时高度小于等于起始高度了,则说明到顶了,状态设为完成刷新
- 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){//如果状态是完成刷新
- if(tempY-startY>0){//如果实时高度大于起始高度了,则状态设为下拉刷新
- state=PULL_To_REFRESH;
- changeHeaderViewByState();
- }
- }
- //更新headView的size
- if(state==PULL_To_REFRESH){//如果状态是下拉刷新,更新headview的size?
- headView.setPadding(0,-1*headContentHeight
- +(tempY-startY),0,0);
- headView.invalidate();
- }
- //更新headView的paddingTop
- if(state==RELEASE_To_REFRESH){//如果状态是松开刷新,更新headview的paddingtop?
- headView.setPadding(0,tempY-startY-headContentHeight,
- 0,0);
- headView.invalidate();
- }
- }
- break;
- }
- returnsuper.onTouchEvent(event);
- }
- //当状态改变时候,调用该方法,以更新界面
- privatevoidchangeHeaderViewByState(){
- switch(state){
- caseRELEASE_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;
- casePULL_To_REFRESH:
- progressBar.setVisibility(View.GONE);
- tipsTextview.setVisibility(View.VISIBLE);
- lastUpdatedTextView.setVisibility(View.VISIBLE);
- arrowImageView.clearAnimation();
- arrowImageView.setVisibility(View.VISIBLE);
- //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");
- }else{
- tipsTextview.setText("下拉刷新");
- }
- Log.v(TAG,"当前状态,下拉刷新");
- break;
- caseREFRESHING:
- headView.setPadding(0,0,0,0);
- headView.invalidate();
- 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;
- caseDONE:
- headView.setPadding(0,-1*headContentHeight,0,0);
- headView.invalidate();
- progressBar.setVisibility(View.GONE);
- arrowImageView.clearAnimation();
- arrowImageView
- .setImageResource(R.drawable.ic_pulltorefresh_arrow);
- tipsTextview.setText("下拉刷新");
- lastUpdatedTextView.setVisibility(View.VISIBLE);
- Log.v(TAG,"当前状态,done");
- break;
- }
- }
- publicvoidsetonRefreshListener(OnRefreshListenerrefreshListener){
- this.refreshListener=refreshListener;
- }
- publicinterfaceOnRefreshListener{
- publicvoidonRefresh();
- }
- publicvoidonRefreshComplete(){
- state=DONE;
- lastUpdatedTextView.setText("最近更新:"+newDate().toLocaleString());//刷新完成时,头部提醒的刷新日期
- changeHeaderViewByState();
- }
- privatevoidonRefresh(){
- 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
- privatevoidmeasureView(Viewchild){
- ViewGroup.LayoutParamsp=child.getLayoutParams();
- if(p==null){
- p=newViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
- ViewGroup.LayoutParams.WRAP_CONTENT);
- }
- intchildWidthSpec=ViewGroup.getChildMeasureSpec(0,0+0,p.width);
- intlpHeight=p.height;
- intchildHeightSpec;
- if(lpHeight>0){
- childHeightSpec=MeasureSpec.makeMeasureSpec(lpHeight,
- MeasureSpec.EXACTLY);
- }else{
- childHeightSpec=MeasureSpec.makeMeasureSpec(0,
- MeasureSpec.UNSPECIFIED);
- }
- child.measure(childWidthSpec,childHeightSpec);
- }
- }
4.head.xml,拷进项目基本不需改:
[html] view plain copy- <?xmlversion="1.0"encoding="utf-8"?>
- <!--ListView的头部-->
- <LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
- android:id="@+id/head_rootLayout"
- android:layout_width="fill_parent"
- android:layout_height="wrap_content">
- <!--内容-->
- <RelativeLayout
- xmlns:android="http://schemas.android.com/apk/res/android"
- android:id="@+id/head_contentLayout"
- android:layout_width="fill_parent"
- android:layout_height="wrap_content"
- 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:id="@+id/head_arrowImageView"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_gravity="center"
- android:src="@drawable/ic_pulltorefresh_arrow"
- android:contentDescription="@string/app_name"/>
- <!--进度条-->
- <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>
- <!--提示、最近更新-->
- <LinearLayout
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_centerHorizontal="true"
- android:gravity="center_horizontal"
- android:orientation="vertical">
- <!--提示-->
- <TextView
- android:id="@+id/head_tipsTextView"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="@string/pulltorefresh"
- android:textColor="#ffffff"
- android:textSize="20sp"/>
- <!--最近更新-->
- <TextView
- android:id="@+id/head_lastUpdatedTextView"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:text="@string/lastupdate"
- android:textColor="#cc6600"
- android:textSize="10sp"/>
- </LinearLayout>
- </RelativeLayout>
- </LinearLayout>
殊途同归,扩展借鉴其他下拉刷新方式:
http://blog.csdn.net/nono_love_lilith/article/details/7100845
http://blog.csdn.net/nono_love_lilith/article/details/7202651
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