Android实现简单的下拉刷新pulltorefresh

2024-03-15 13:52:03 36

网上下拉刷新的DEMO很多，但是总有各种不满意的地方，有些会下拉卡住，有些回弹不流畅，有些性能太低会各种卡顿，有些emptyView无法下拉......

自己写的才是最合适自己的，代码很简单，也很容易修改，稍微阅读下代码就能改出自己需要的各种效果。

首先，重写ListView，自定义Touch事件，为了使emptyView也可下拉，emptyView也加上Touch事件。如果要实现GridView，把这里的ListView改成GridView即可。

PullableListView：

publicclassPullableListViewextendsListView{
privatebooleaninited;
privatefloatdensity;
privateintmDownY,mMoveY;
privateintmPullY;
privatebooleanisPull;
privatePullListenermPullListener;
privateVelocityTrackermVelocityTracker;

publicinterfacePullListener{

publicbooleanonPullDownStart();

publicvoidonPullDown(intmoveY);

publicvoidonPullDownDrop();
}

publicPullableListView(Contextcontext,AttributeSetattrs,intdefStyle){
super(context,attrs,defStyle);
init();
}

publicPullableListView(Contextcontext,AttributeSetattrs){
super(context,attrs);
init();
}

publicPullableListView(Contextcontext){
super(context);
init();
}

privatevoidinit(){
if(!inited){
density=getResources().getDisplayMetrics().density;
}
}

publicvoidsetPullListener(PullListenermPullListener){
this.mPullListener=mPullListener;
}

publicbooleanisPulling(){
returnisPull;
}

@Override
publicvoidsetEmptyView(ViewemptyView){
super.setEmptyView(emptyView);
//重写emptyView的Touch事件，使显示emptyView时也可以下拉刷新
emptyView.setOnTouchListener(newOnTouchListener(){
@Override
publicbooleanonTouch(Viewv,MotionEventev){
if(mVelocityTracker==null){
mVelocityTracker=VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
switch(ev.getAction()){
caseMotionEvent.ACTION_DOWN:
mDownY=(int)ev.getY();
break;
caseMotionEvent.ACTION_MOVE:
mMoveY=(int)ev.getY();
if(!isPull){
mVelocityTracker.computeCurrentVelocity(1000,8000f);
if(mVelocityTracker.getYVelocity()>500//下拉速度大于500
&&Math.abs(mMoveY-mDownY)>20*density){//下拉距离超过20dp
mPullY=mMoveY;
if(mPullListener.onPullDownStart()){
isPull=true;
}
}
}else{
//阻尼下拉(随着下拉距离增加，阻力增加)
mPullListener.onPullDown(mMoveY-mPullY+v.getScrollY());
//等阻力下拉(阻力恒定，不随下拉距离增加而增加)
//mPullListener.onPullDown(mMoveY-mPullY);
if(mMoveY<mPullY){
isPull=false;
}
returntrue;
}
break;
caseMotionEvent.ACTION_UP:
if(mVelocityTracker!=null){
mVelocityTracker.clear();
mVelocityTracker.recycle();
mVelocityTracker=null;
}
if(isPull){
mPullY=0;
isPull=false;
mPullListener.onPullDownDrop();
returntrue;
}
break;
}
returntrue;
}
});
}

@Override
publicbooleanonInterceptTouchEvent(MotionEventev){
if(isPull){
//正在下拉时，阻住Touch事件向下传递，同时会向各个ChildView发送ACTION_CANLE事件，
//使之前捕捉到了ACTION_DOWN事件的ChildView回复到正常状态
returntrue;
}

returnsuper.onInterceptTouchEvent(ev);
}

@Override
publicbooleanonTouchEvent(MotionEventev){
if(mVelocityTracker==null){
mVelocityTracker=VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
switch(ev.getAction()){
caseMotionEvent.ACTION_DOWN:
mDownY=(int)ev.getY();
break;
caseMotionEvent.ACTION_MOVE:
mMoveY=(int)ev.getY();
if(!isPull){
if(getFirstVisiblePosition()==0){
Viewview=getChildAt(0);
mVelocityTracker.computeCurrentVelocity(1000,8000f);
if(mVelocityTracker.getYVelocity()>500//下拉速度大于500
&&(view==null||view.getTop()==getPaddingTop())//已拉动到顶部
&&Math.abs(mMoveY-mDownY)>15*density){//下拉距离超过20dp
mPullY=mMoveY;
if(mPullListener.onPullDownStart()){
//根据返回值确认是否进入下拉状态
isPull=true;
}
}
}
}else{
//阻尼下拉(随着下拉距离增加，阻力增加)
mPullListener.onPullDown(mMoveY-mPullY);
//等阻力下拉(阻力恒定，不随下拉距离增加而增加)
//mPullListener.onPullDown(mMoveY-mPullY-getScrollY());
if(mMoveY<mPullY){
isPull=false;
}
returntrue;
}
break;
caseMotionEvent.ACTION_UP:
if(mVelocityTracker!=null){
mVelocityTracker.clear();
mVelocityTracker.recycle();
mVelocityTracker=null;
}
if(isPull){
mPullY=0;
isPull=false;
mPullListener.onPullDownDrop();
returntrue;
}
break;
caseMotionEvent.ACTION_CANCEL:
break;
}
returnsuper.onTouchEvent(ev);
}
}

然后是外层的LinearyLayer，监听PullableListView的下拉回调，实现下拉效果。同时提供ListView(GridView)的外部接口，如setEmptyView(Viewview),setAdapter(ListAdapteradapter)...等等，这里只提供部分我需要使用的，可以根据自身需求去提供外部接口。
代码中R.drawable.pulltorefresh和R.drawable.loading分别是下拉箭头和刷新滚动条的图片，这里不提供了，自己随意找两张图片贴上就行了。

PullToRefreshView：

publicclassPullToRefreshViewextendsLinearLayout{

protectedstaticfinalStringTAG="PullToRefreshView";

/**
*下拉阻力系数
*/
privatestaticfinalfloatSCALL_PULL_DOWW=2.0f;

privateViewmView;

privatePullableListViewmListView;

privateTextViewmPullTv;

privateImageViewmProgressBar;

privateViewmPullV;

privateViewmEmptyView;

privatebooleanisInited;

privatebooleancanRefresh;

privatebooleanisRefreshing;

privatebooleanisPullable=true;

privateintmOrMargin;

privateObjectAnimatormArrowRotateAnimator;

privateAnimationmProAnimation;

privatePullToRefreshListenermPullToRefreshListener;

publicPullToRefreshView(Contextcontext,AttributeSetattrs,intdefStyle){
super(context,attrs,defStyle);
initView(context);
}

publicPullToRefreshView(Contextcontext,AttributeSetattrs){
super(context,attrs);
initView(context);
}

publicPullToRefreshView(Contextcontext){
super(context);
initView(context);
}

publicinterfacePullToRefreshListener{
/**
*dodatarefreshhere
*/
publicvoidonRefreshStart();

/**
*doviewupdatehere
*/
publicvoidonRefreshFinished();
}

privatevoidinitView(Contextcontext){
if(!isInited){
isInited=true;
mView=LayoutInflater.from(context).inflate(R.layout.view_pulltorefresh,null);
mProgressBar=(ImageView)mView.findViewById(R.id.iv_pulltorefresh_arrow);
mProgressBar.setImageResource(R.drawable.pulltorefresh);
mPullTv=(TextView)mView.findViewById(R.id.tv_pulltorefresh);
mPullV=mView.findViewById(R.id.ly_pulltorefresh_pull);
mListView=(PullableListView)mView.findViewById(R.id.gv_smarturc_urcs);
mListView.setPullListener(mPullListener);
LayoutParamslp=newLayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT);
addView(mView,lp);
LayoutParamslParams=(LayoutParams)mPullV.getLayoutParams();
mOrMargin=lParams.topMargin;
mProAnimation=AnimationUtils.loadAnimation(getContext(),
R.anim.anim_progressbar);
}
}

privatePullListenermPullListener=newPullListener(){

@Override
publicbooleanonPullDownStart(){
if(isRefreshing||!isPullable){
returnfalse;
}
mPullTv.setText("下拉刷新");
mProgressBar.setRotation(0f);
mProgressBar.setImageResource(R.drawable.pulltorefresh);
if(mProgressBar.getAnimation()!=null){
mProgressBar.clearAnimation();
}
returntrue;
}

@Override
publicvoidonPullDown(intmoveY){
if(isRefreshing||!isPullable){
return;
}
moveY=(int)Math.max(0,moveY/SCALL_PULL_DOWW);
mView.scrollTo(0,-moveY);
mEmptyView.scrollTo(0,-moveY);
if(!canRefresh
&&Math.abs(mView.getScrollY())>Math.abs(mOrMargin)){
mPullTv.setText("松开刷新");
canRefresh=true;
if(mArrowRotateAnimator!=null){
mArrowRotateAnimator.cancel();
}
floatrotation=mProgressBar.getRotation();
mArrowRotateAnimator=ObjectAnimator.ofFloat(mProgressBar,"rotation",
rotation,180f);
mArrowRotateAnimator.setDuration(100).start();
}elseif(canRefresh
&&Math.abs(mView.getScrollY())<=Math.abs(mOrMargin)){
mPullTv.setText("下拉刷新");
canRefresh=false;
if(mArrowRotateAnimator!=null){
mArrowRotateAnimator.cancel();
}
floatrotation=mProgressBar.getRotation();
mArrowRotateAnimator=ObjectAnimator.ofFloat(mProgressBar,"rotation",
rotation,0f);
mArrowRotateAnimator.setDuration(100).start();
}
}

@Override
publicvoidonPullDownDrop(){
if(canRefresh){
setRefreshing();
}else{
isRefreshing=false;
backTo(mView.getScrollY(),0);
}
}
};

privatevoidbackTo(finalintfrom,finalintto){
ObjectAnimator.ofInt(mView,"scrollY",from,to).setDuration(300)
.start();
ObjectAnimator.ofInt(mEmptyView,"scrollY",from,to).setDuration(300)
.start();
}

/**
*设置为正在刷新状态
*/
publicvoidsetRefreshing(){
isRefreshing=true;
mProgressBar.setImageResource(R.drawable.loading);
mProgressBar.startAnimation(mProAnimation);
mPullTv.setText("正在刷新");
backTo(mView.getScrollY(),mOrMargin);
if(mPullToRefreshListener!=null){
mPullToRefreshListener.onRefreshStart();
}
}

/**
*刷新完成
*/
publicvoidsetRrefreshFinish(){
if(isRefreshing){
isRefreshing=false;
backTo(mView.getScrollY(),0);
}
if(mPullToRefreshListener!=null){
mPullToRefreshListener.onRefreshFinished();
}
}

publicvoidsetPullable(booleanpullable){
isPullable=pullable;
}

publicvoidsetPullToRefreshListener(
PullToRefreshListenermPullToRefreshListener){
this.mPullToRefreshListener=mPullToRefreshListener;
}

publicvoidsetAdapter(ListAdapteradapter){
mListView.setAdapter(adapter);
}

publicvoidsetEmptyView(ViewemptyView){
mListView.setEmptyView(emptyView);
this.mEmptyView=emptyView;
}

publicvoidsetOnItemClickListener(OnItemClickListeneritemClickListener){
mListView.setOnItemClickListener(itemClickListener);
}

publicvoidsetOnItemLongClickListener(OnItemLongClickListeneritemLongClickListener){
mListView.setOnItemLongClickListener(itemLongClickListener);
}
}

layout-view_pulltorefresh:

<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#cccccc"
android:orientation="vertical">

<LinearLayout
android:id="@+id/ly_pulltorefresh_pull"
android:layout_width="wrap_content"
android:layout_height="48dp"
android:layout_gravity="center_horizontal"
android:layout_marginTop="-48dp">

<ImageView
android:id="@+id/iv_pulltorefresh_arrow"
android:layout_width="20dp"
android:layout_height="match_parent"
android:scaleType="fitCenter"
android:src="@drawable/pulltorefresh"/>

<TextView
android:id="@+id/tv_pulltorefresh"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_marginBottom="4dp"
android:layout_marginLeft="8dp"
android:gravity="center"
android:textColor="@android:color/white"
android:textSize="16sp"/>
</LinearLayout>

<com.example.pulltorefresh.PullableListView
android:id="@+id/gv_smarturc_urcs"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/transparent"
android:overScrollMode="never"
android:scrollingCache="false">
</com.example.pulltorefresh.PullableListView>

</LinearLayout>

anim-anim_progressbar:

<?xmlversion="1.0"encoding="utf-8"?>
<rotatexmlns:android="http://schemas.android.com/apk/res/android"
android:fromDegrees="0"
android:toDegrees="360"
android:pivotX="50%"
android:pivotY="50%"
android:repeatCount="infinite"
android:repeatMode="restart"
android:duration="800"
android:interpolator="@android:anim/linear_interpolator"/>

最后是DEMOACTIVITY：

publicclassPullToRefreshActivityextendsActivity{

privatePullToRefreshViewmPullToRefreshView;
privateList<String>data=newArrayList<String>();
privateMyAdaptermAdapter;
privateHandlermHandler;

@Override
protectedvoidonCreate(BundlesavedInstanceState){
//TODOAuto-generatedmethodstub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pulltorefresh);
mHandler=newHandler();
mPullToRefreshView=(PullToRefreshView)findViewById(R.id.pullToRefreshView1);
mAdapter=newMyAdapter();
mPullToRefreshView.setAdapter(mAdapter);
mPullToRefreshView.setEmptyView(findViewById(R.id.empty));
mPullToRefreshView.setOnItemLongClickListener(newOnItemLongClickListener(){
@Override
publicbooleanonItemLongClick(AdapterView<?>parent,Viewview,intposition,longid){
Toast.makeText(getApplicationContext(),"Longclick:"+data.get(position),
Toast.LENGTH_SHORT).show();
returntrue;
}
});
mPullToRefreshView.setOnItemClickListener(newOnItemClickListener(){
@Override
publicvoidonItemClick(AdapterView<?>parent,Viewview,intposition,longid){
Toast.makeText(getApplicationContext(),data.get(position),Toast.LENGTH_SHORT)
.show();
}
});
mPullToRefreshView.setPullToRefreshListener(newPullToRefreshListener(){
@Override
publicvoidonRefreshStart(){
//模拟刷新数据
mHandler.postDelayed(newRunnable(){
@Override
publicvoidrun(){
data.add(String.valueOf((int)(Math.random()*1000)));
mPullToRefreshView.setRrefreshFinish();
}
},2000);
}

@Override
publicvoidonRefreshFinished(){
//更新视图
mAdapter.notifyDataSetChanged();
}
});
//mHandler.postDelayed(newRunnable(){
//@Override
//publicvoidrun(){
////TODOAuto-generatedmethodstub
//mPullToRefreshView.setRefreshing();
//}
//},500);
}

publicclassMyAdapterextendsBaseAdapter{

@Override
publicintgetCount(){
//TODOAuto-generatedmethodstub
returndata.size();
}

@Override
publicObjectgetItem(intposition){
//TODOAuto-generatedmethodstub
returndata.get(position);
}

@Override
publiclonggetItemId(intposition){
//TODOAuto-generatedmethodstub
returnposition;
}

@Override
publicViewgetView(intposition,ViewconvertView,ViewGroupparent){
//TODOAuto-generatedmethodstub
if(convertView==null){
convertView=newTextView(PullToRefreshActivity.this);
}
TextViewtextView=(TextView)convertView;
textView.setTextSize(TypedValue.COMPLEX_UNIT_SP,40f);
textView.setPadding(30,30,30,30);
textView.setText(data.get(position));
returnconvertView;
}

}
}

layout-activity_pulltorefresh:

<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">

<com.example.pulltorefresh.PullToRefreshView
android:id="@+id/pullToRefreshView1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true">
</com.example.pulltorefresh.PullToRefreshView>

<LinearLayout
android:id="@+id/empty"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical"
android:padding="60dp">

<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_launcher"/>

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="NODATA"/>
</LinearLayout>

</RelativeLayout>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。

Android实现简单的下拉刷新pulltorefresh

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