【移動(dòng)應(yīng)用開發(fā)技術(shù)】PullToRefreshScrollView+GridView，實(shí)現(xiàn)向下滑動(dòng)中隱藏自定義Action布局

最近電商類項(xiàng)目有個(gè)需求挺頭疼，要求用GridView去顯示商品，滑動(dòng)到底部下拉能加載更多商品，向下滑動(dòng)過程中需要隱藏掉自定義的Action布局，向上滑動(dòng)能顯示出來，整體效果類似淘寶APP搜索結(jié)果頁(yè)那樣。

起初覺得挺簡(jiǎn)單的，但是后來才發(fā)現(xiàn)還是得轉(zhuǎn)一點(diǎn)腦子。最開始我想用PullToRefreshGridView，但是后來發(fā)現(xiàn)GridView沒有添加headview的方法，只能采用PullToRefreshScrollView內(nèi)嵌套GridView的方法，Scrollview里多放一個(gè)空白布局當(dāng)GridView的headview，高度和Action布局一樣就行。這時(shí)還有一個(gè)問題，ScrollView和GridView會(huì)產(chǎn)生滑動(dòng)沖突，還好網(wǎng)上很容易找到解決辦法，我這里采用自定義GridView，最后就是監(jiān)聽方法了，最為關(guān)鍵的點(diǎn),還是直接上代碼吧：自定義GridView：packagecom.example.ztestscrollview;importandroid.content.Context;importandroid.util.AttributeSet;importandroid.view.View.MeasureSpec;importandroid.widget.GridView;publicclassMyGridViewextendsGridView{publicMyGridView(Contextcontext,AttributeSetattrs){

super(context,attrs);}publicMyGridView(Contextcontext){

super(context);}publicMyGridView(Contextcontext,AttributeSetattrs,intdefStyle){

super(context,attrs,defStyle);}@Override

publicvoidonMeasure(intwidthMeasureSpec,intheightMeasureSpec){

intexpandSpec=MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE>>2,

MeasureSpec.AT_MOST);

super.onMeasure(widthMeasureSpec,expandSpec);}

}主界面：packagecom.example.ztestscrollview;importandroid.app.Activity;importandroid.os.Bundle;importandroid.util.Log;importandroid.view.Menu;importandroid.view.MotionEvent;importandroid.view.View;importandroid.view.View.OnTouchListener;importandroid.view.ViewGroup;importandroid.widget.BaseAdapter;importandroid.widget.ScrollView;importcom.handmark.pulltorefresh.library.PullToRefreshBase;importcom.handmark.pulltorefresh.library.PullToRefreshBase.Mode;importcom.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;importcom.handmark.pulltorefresh.library.PullToRefreshScrollView;publicclassMainActivityextendsActivity{

intnum=10;

privateGridAdapteradapter;

privateScrollViewscrollView;

privatePullToRefreshScrollViewptr_scrollview;

privateViewactionLayout;

privateMyGridViewmyGridview;

@Override

protectedvoidonCreate(BundlesavedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

actionLayout=findViewById(R.id.actionlayout);

ptr_scrollview=(PullToRefreshScrollView)findViewById(R.id.ptr_scrollview);

ptr_scrollview.setMode(Mode.PULL_UP_TO_REFRESH);

ptr_scrollview.setOnRefreshListener(newOnRefreshListener<ScrollView>()

{

@Override

publicvoidonRefresh(PullToRefreshBase<ScrollView>refreshView)

{

num+=10;

adapter.notifyDataSetChanged();

ptr_scrollview.onRefreshComplete();

}

});

myGridview=(MyGridView)findViewById(R.id.myGridView1);

adapter=newGridAdapter();

myGridview.setAdapter(adapter);

scrollView=ptr_scrollview.getRefreshableView();

scrollView.setOnTouchListener(newOnTouchListener()

{

//判斷是否第一個(gè)滑動(dòng)值

booleanisFirst=true;

//Scrollview滑動(dòng)的ScrollY值

privateintScrollY_Move;

//第一個(gè)滑動(dòng)的ScrollY值

privateintFirst_ScrollY_Move;

//手指抬起時(shí)ScrollY值

privateintScrollY_Up;

//ScrollY_Move和First_ScrollY_Move的差值

privateintCha;

@Override

publicbooleanonTouch(Viewv,MotionEventevent)

{

switch(event.getAction())

{

//ACTIN_DOWN沒用，不用監(jiān)聽

caseMotionEvent.ACTION_MOVE:

if(isFirst)

{

//記錄下第一個(gè)滑動(dòng)的ScrollY值

First_ScrollY_Move=v.getScrollY();

isFirst=false;

}

//記錄下Scrollview滑動(dòng)的ScrollY值

ScrollY_Move=v.getScrollY();

//計(jì)算出ScrollY_Move和First_ScrollY_Move的差值

Cha=ScrollY_Move-First_ScrollY_Move;

//當(dāng)ScrollY_Move>First_ScrollY_Move時(shí)證明滑動(dòng)方向是向下；

//加上判斷差值的目的：當(dāng)Actionbar顯示的時(shí)候，手指按住往下滑過一段距離還未抬起時(shí)，Actionbar也能隱藏

if(First_ScrollY_Move<ScrollY_Move||Cha>200)

{

//隱藏Actionbar

actionLayout.setVisibility(View.GONE);

}

//當(dāng)ScrollY_Move<First_ScrollY_Move時(shí)證明滑動(dòng)方向是向上；

//加上判斷差值的目的：當(dāng)Actionbar顯示的時(shí)候，手指按住往上滑過一段距離還未抬起時(shí)，Actionbar也能顯示

//判斷ScrollY_Move<150目的：當(dāng)Scrollview滑動(dòng)接近頂端時(shí)必須顯示Actionbar

elseif(First_ScrollY_Move>ScrollY_Move||Cha<-200

||ScrollY_Move<150)

{

actionLayout.setVisibility(View.VISIBLE);

}

break;

caseMotionEvent.ACTION_UP:

ScrollY_Up=v.getScrollY();//記錄下手指抬起時(shí)ScrollY值

isFirst=true;//將isFirst還原為初始化

if(ScrollY_Up==0)

{

actionLayout.setVisibility(View.VISIBLE);

}

//Log.e("ACTION_UP>","scrollY_up:"+scrollY_up+"

"

//+"eventY_up:"+eventY_up);

break;

default:

break;

}

returnfalse;

}

});

}

classGridAdapterextendsBaseAdapter

{

@Override

publicViewgetView(intposition,ViewconvertView,ViewGroupparent)

{

Viewinflate=getLayoutInflater().inflate(R.layout.griditem,null);

returninflate;

}

@Override

publicintgetCount()

{

//TODOAuto-generatedmethodstub

returnnum;

}

@Override

publicObjectgetItem(intposition)

{

//TODOAuto-generatedmethodstub

returnnull;

}

@Override

publiclonggetItemId(intposition)

{

//TODOAuto-generatedmethodstub

return0;

}

}

@Override

publicbooleanonCreateOptionsMenu(Menumenu)

{

//Inflatethemenu;thisaddsitemstotheactionbarifitispresent.

getMenuInflater().inflate(R.menu.main,menu);

returntrue;

}}布局：<RelativeLayoutxmlns:android="/apk/res/android"

xmlns:tools="/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".MainActivity">

<com.handmark.pulltorefresh.library.PullToRefreshScrollView

android:id="@+id/ptr_scrollview"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layout_alignParentLeft="true"

android:layout_alignParentTop="true">

<RelativeLayout

android:layout_width="match_parent"

android:layout_height="match_parent"

android:descendantFocusability="blocksDescendants">

<RelativeLayout

android:id="@+id/headview"

android:layout_width="match_parent"

android:layout_height="120dp"

android:layout_alignParentLeft="true"

android:layout_alignParentTop="true">

</RelativeLayout>

<com.example.ztestscrollview.MyGridView

android:id="@+id/myGridView1"

android:layout_width="match_parent"