使用AndroidSwipeRefreshLayout了解Android的嵌套滑動機(jī)制SwipeRefreshLayout是在AndroidSupportLibrary,revision19.1.0添加到supportv4庫中的一個下拉刷新控件，關(guān)于android的下拉刷新框架現(xiàn)在有好多，曾經(jīng)用過XListView，現(xiàn)在工作中基本上無需用到下拉刷新的功能。廢話不多說了，這里來記錄一下android自帶的刷新控件SwipeRefreshLayout的使用，借此順便來熟悉一下android在Lollipop版本推出的嵌套滑動機(jī)制(NestedScrolli)g。首先來看SwipeRefreshLayout的使用，使用很簡單，看一下布局文件[html]viewplaincopyC<?xmlversion=T.0"encoding="utf-8"?><android.support?v4?widget.SwipeRefreshLayoutxmlns:android="/apk/res/android"xmlns:tools="/tools"android:id="@+id/swiperefresh"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".recyclerviewdemo.RecyclerViewActivity">8.<android.support?v7?widget.RecyclerViewandroid:id="@+id/my_recycler_view"android:layout_width="match_parent"android:layout_height="wrap_content"/></android.support?v4?widget.SwipeRefreshLayout〉注意SwipeRefreshLayout只能有一個直接的子View。這里用了RecyclerView，因?yàn)榍懊鎰倓傊v過它。其實(shí)用啥子View都行，只要你想通過豎直方向的滑動來刷新該View的顯示內(nèi)容。關(guān)于SwipeRefreshLayout的一些API:

..1.22.swipeRefreshLayout=(SwipeRefreshLayout)findViewByld(R.id.swiperefresh);mRecyclerView=(RecyclerView)findViewById(R.id.my_recycler_view);swipeRefreshLayout.setSize(SwipeRefreshLayout.LARGE);//swipeRefreshLayout.setSize(SwipeRefreshLayout.DEFAULT);//默認(rèn)設(shè)置進(jìn)度圈的大小，只有兩個值：DEFAULT、LARGE//swipeRefreshLayout.setProgressBackgroundColorSchemeColor(Color.RED);//設(shè)置進(jìn)度圈的背景色。//swipeRefreshLayout.setColorSchemeResources(R.color.colorPrimaryDark,R.color.colorPrimary,R.color.cardViewcolor);//設(shè)置進(jìn)度動畫的顏色swipeRefreshLayout.setOnRefreshListener(newSwipeRefreshLayout.OnRefreshListener(){@OverridepublicvoidonRefresh(){Log.d(”test","onRefresh");datas.add(0,newContact("xiaochen",T0086"));handler.postDelayed(newRunnable(){@Overridepublicvoidrun(){mAdapter.notifyDataSetChanged();swipeRefreshLayout.setRefreshing(false);//設(shè)置刷新狀態(tài)false停止刷新}},5000);}});

這里還是根據(jù)前文的demo來寫的，就刷新的時候，在第一個位置添加一條數(shù)據(jù)，咱看效果:KEftonhen10066130^221111133333T111如口亡hwi13Q44441111MH9H1306664*^111XFBDhO<H}13Q77771111SwipeRefreshLayout的使用沒啥好講的，比較簡單。咱再一張效果圖：m鋼斤畫卻瑪喬—->刪棄第's—->down刪棄、N->Move刪棄、—->up刪棄'滉刮卻亠一」凹龍爍営Move刪棄罟罠和母SwipeRefreshLayout(圧営ffi^H)甘Recyc-erview()幾厚隔7'iclja四畫前甜①于Andl-oid謬耕刪棄洋隔汩歴—邸卻亠一」卩于(4'android<-Q?i'11K滉越?—瞑咄犧修制凹龍克聖—->刪棄第畫母母Jvhview^隔'iSwipeRefreshLayout甘Recyc-erview迓謬耕刪亠￡g^隔^諭克7—冊^隔。耳lu?^##swipeRefreshLayout甘Recyc-erviewS前甜禰冊瑪莎制訊?于*亠_」前甜#*=,昴卜厚隔刪棄'-〔html〕viewp-aincopyn1?publicclassswipeRe-FreshLayour+exr+endsViewGroupimplemenr+sNesr+edscrollingparenr2?Nesr+edscrollingchild宀[html]viewplaincopyprivatefinalNestedScrollingParentHelpermNestedScrollingParentHelper;privatefinalNestedScrollingChildHelpermNestedScrollingChildHelper;SwipeRefreshLayout實(shí)現(xiàn)了NestedScrollingParent接口，同時它也有一個成員變量是NestedScrollingParentHelper類型[html]viewplaincopyC1.publicclassRecyclerViewextendsViewGroupimplementsScrollingView,NestedScrollingChild{[html]viewplaincopy1.privateNestedScrollingChildHelpermScrollingChildHelper;RecyclerView實(shí)現(xiàn)了NestedScrollingChild接口，同時它也有一個成員變量是NestedScrollingChildHelper類型發(fā)現(xiàn)了四個新的對象NestedScrollingParent,NestedScrollingChild,NestedScrollingChildHelper,NestedScrollingParentHelper。前面說嵌套滑動機(jī)制主要由上面四個對象來實(shí)現(xiàn)的，SwipeRefreshLayout和RecyclerView之間就是利用嵌套滑動來實(shí)現(xiàn)下拉刷新的，大家有興趣可以閱讀源碼去分析。下面講一下android這個嵌套滑動機(jī)制Android在發(fā)布Lollipop版本之后，為了更好的用戶體驗(yàn)，Google為Android的滑動機(jī)制提供了NestedScrolling特性理解嵌套滑動，需要理解以下幾個類（接口）：NestedScrollingChildNestedScrollingParentNestedScrollingChildHelperNestedScrollingParentHelper以上四個類都在support-v4包(AndroidSupportLibrary,revision22.1.0添加的)中提供，Lollipop的View默認(rèn)實(shí)現(xiàn)了幾種方法。先來看NestedScrollingChild接口，顧名思義，這個是子View應(yīng)該實(shí)現(xiàn)的接口:[java]viewplaincopy1./**Copyright(C)2015TheAndroidOpenSourceProjectTOC\o"1-5"\h\z**LicensedundertheApacheLicense,Version2.0(the"License");*youmaynotusethisfileexceptincompliancewiththeLicense.*YoumayobtainacopyoftheLicenseat** /licenses/LICENSE-2.0** Unlessrequiredbyapplicablelaworagreedtoinwriting,software* distributedundertheLicenseisdistributedonan"ASIS"BASIS,* WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.* SeetheLicenseforthespecificlanguagegoverningpermissionsand* limitationsundertheLicense.*/16.17.packageandroid.support.v4.view;19.importandroid.view.MotionEvent;importandroid.view.VelocityTracker;importandroid.view.View;importandroid.view.ViewConfiguration;24.import24.importandroid.view.ViewParent;/***Thisinterfaceshouldbeimplementedby{@linkandroid.view.ViewView}subclassesthatwish*tosupportdispatchingnestedscrollingoperationstoacooperatingparent*{@linkandroid.view.ViewGroupViewGroup}.**<p>Classesimplementingthisinterfaceshouldcreateafinalinstanceofa*{@linkNestedScrollingChildHelper}asafieldanddelegateanyViewmethodstothe*<code>NestedScrollingChildHelper</code>methodsofthesamesignature.</p>**<p>Viewsinvokingnestedscrollingfunctionalityshouldalwaysdosofromtherelevant*{@linkViewCompat},{@linkViewGroupCompat}or{@linkViewParentCompat}compatibility*shimstaticmethods.ThisensuresinteroperabilitywithnestedscrollingviewsonAndroid*5.0Lollipopandnewer.</p>TOC\o"1-5"\h\z*/publicinterfaceNestedScrollingChild{/***Enableordisablenestedscrollingforthisview.**<p>Ifthispropertyissettotruetheviewwillbepermittedtoinitiatenested*scrollingoperationswithacompatibleparentviewinthecurrenthierarchy.Ifthis

0.viewdoesnotimplementnestedscrollingthiswillhavenoeffect.Disablingnestedscrollingwhileanestedscrollisinprogresshastheeffectof{@link#stopNestedScroll()stopping}thenestedscroll.</p>*@paramenabledtruetoenablenestedscrolling,falsetodisable*@see#isNestedScrollingEnabled()*/publicvoidsetNestedScrollingEnabled(booleanenabled);/**Returnstrueifnestedscrollingisenabledforthisview.*<p>IfnestedscrollingisenabledandthisViewclassimplementationsupportsit,thisviewwillactasanestedscrollingchildviewwhenapplicable,forwardingdataaboutthescrolloperationinprogresstoacompatibleandcooperatingnestedscrollingparent.</p>*@returntrueifnestedscrollingisenabled**@see#setNestedScrollingEnabled(boolean)*/publicbooleanisNestedScrollingEnabled();/**

7.88.*<p>Aviewstartinganestedscrollpromisestoabidebythefollowingcontract:</p>*<p>TheviewwillcallstartNestedScrolluponinitiatingascrolloperation.Inthecaseofatouchscrollthiscorrespondstotheinitial{@linkMotionEvent#ACTION_DOWN}.Inthecaseoftouchscrollingthenestedscrollwillbeterminatedautomaticallyinthesamemanneras{@linkViewParent#requestDisallowInterceptTouchEvent(boolean)}.Intheeventofprogrammaticscrollingthecallermustexplicitlycall{@link#stopNestedScroll()}toindicatetheendofthenestedscroll.</p>*<p>If<code>startNestedScroll</code>returnstrue,acooperativeparentwasfound.Ifitreturnsfalsethecallermayignoretherestofthiscontractuntilthenextscroll.CallingstartNestedScrollwhileanestedscrollisalreadyinprogresswillreturntrue.</p>*<p>Ateachincrementalstepofthescrollthecallershouldinvoke{@link#dispatchNestedPreScroll(int,int,int[],int[])dispatchNestedPreScroll}onceithascalculatedtherequestedscrollingdelta.Ifitreturnstruethenestedscrolling*parentatleastpartiallyconsumedthescrollandthecallershouldadjusttheamountit*scrollsby.</p>**<p>Afterapplyingtheremainderofthescrolldeltathecallershouldinvoke*{@link#dispatchNestedScroll(int,int,int,int,int[])dispatchNestedScroll},passing*boththedeltaconsumedandthedeltaunconsumed.Anestedscrollingparentmaytreat* these values differently. See* {@link NestedScrollingParent#onNestedScroll(View,int,int,int,int)}.* </p>**@paramaxesFlagsconsistingofacombinationof{@linkViewCompat#SCROLL_AXIS_HORIZONTAL}* and/or{@linkViewCompat#SCROLL_AXIS_VERTICAL}.*@returntrueifacooperativeparentwasfoundandnestedscrollinghasbeenenabledfor* thecurrentgesture.TOC\o"1-5"\h\z** @see #stopNestedScroll()* @see #dispatchNestedPreScroll(int, int, int[], int[])* @see #dispatchNestedScroll(int, int, int, int, int[])*/publicbooleanstartNestedScroll(intaxes);109./***Stopanestedscrollinprogress.

112.*113.*<p>Callingthismethodwhenanestedscrollisnotcurrentlyinprogressisharmless.</p>114.*115.*@see#startNestedScroll(int)116.*/117.publicvoidstopNestedScroll();118.119./**120.*Returnstrueifthisviewhasanestedscrollingparent?121.*122.*<p>Thepreseneeofanestedscrollingparentindicatesthatthisviewhasinitiated123.*anestedscrollanditwasacceptedbyanancestorviewfurtheruptheviewhierarchy.</p>124.*125.*@returnwhetherthisviewhasanestedscrollingparent126.*/127.publicbooleanhasNestedScrollingParent();128.129./**130.*Dispatchonestepofanestedscrollinprogress?131.*132.*<p>Implementationsofviewsthatsupportnestedscrollingshouldcallthistoreport133.*infoaboutascrollinprogresstothecurrentnestedscrollingparent.Ifanestedscroll134.*isnotcurrentlyinprogressornestedscrollingisnot135.*{@link#isNestedScrollingEnabled()enabled}forthisviewthismethoddoesnothing.</p>136137138139140141142143144145146147148149150151152153154155, @returntrueiftheeventwasdispatched,falseifitcouldnotbedispatched.@returntrueiftheeventwasdispatched,falseifitcouldnotbedispatched.*@see#dispatchNestedPreScroll(int,int,int[],int[])*/publicbooleandispatchNestedScroll(intdxConsumed,intdyConsumed,intdxUnconsumed,intdyUnconsumed,int[]offsetInWindow);, *{@link#dispatchNestedPreScroll(int,int,int[],int[])dispatchNestedPreScroll}before, *consumingacomponentofthescrolleventthemselves.</p>*, *@paramdxConsumedHorizontaldistanceinpixelsconsumedbythisviewduringthisscrollstep, *@paramdyConsumedVerticaldistanceinpixelsconsumedbythisviewduringthisscrollstep@paramdxUnconsumedHorizontalscrolldistanceinpixelsnotconsumedbythisview@paramdyUnconsumedHorizontalscrolldistanceinpixelsnotconsumedbythisview@paramoffsetInWindowOptional.Ifnotnull,onreturnthiswillcontaintheoffsetinlocalviewcoordinatesofthisviewfrombeforethisoperationtoafteritcompletes.Viewimplementationsmansumesanyportionofit.yusethistoadjust*expectedinputcoordinatetracking.yusethistoadjust*expectedinputcoordinatetracking.*<p>Nestedpre-scrolleventsaretonestedscrolleventswhattouchinterceptistotouch.<code>dispatchNestedPreScroll</code>offersanopportunityfortheparentviewinanestedscrollingoperationtoconsumesomeorallofthescrolloperationbeforethechildview. toafteritcompletes.Viewimplementationsmausethistoadjusttoafteritcompletes.Viewimplementationsmausethistoadjustexpectedinputcoordinatetracking.*@returntrueiftheparentconsumedsomeorallofthescrolldelta*@see#dispatchNestedScroll(int,int,int,int,int[])*/publicbooleandispatchNestedPreScroll(intdx,intdy,int[]consumed,int[]offsetInWindow);*@paramdxHorizontalscrolldistanceinpixels@paramdyVerticalscrolldistanceinpixels@paramconsumedOutput.Ifnotnull,consumed[0]willcontaintheconsumedcomponentofdxandconsumed[1]theconsumeddy.*@paramoffsetInWindowOptional.Ifnotnull,onreturnthiswillcon156157158159160161162163164165166167168169170171172173174175176taintheoffsettaintheoffsetinlocalviewcoordinatesofthisviewfrombeforethisoperationforethisoperation

*. *<p>Thismethodshouldbeusedtoindicatethatanestedscrollingchildhasdetected. *suitableconditionsforafling.Generallythismeansthatatouchscrollhasendedwitha. *{@linkVelocityTrackervelocity}inthedirectionofscrollingthatmeetsorexceeds. *the{@linkViewConfiguration#getScaledMinimumFlingVelocity()minimumflingvelocity}. *alongascrollableaxis.</p>*. *<p>Ifanestedscrollingchildviewwouldnormallyflingbutitisattheedgeof. *itsowncontent,itcanusethismethodtodelegatetheflingtoitsnestedscrolling. *parentinstead.Theparentmayoptionallyconsumetheflingorobserveachildfling.</p>*. *@paramvelocityXHorizontalflingvelocityinpixelspersecond. *@paramvelocityYVerticalflingvelocityinpixelspersecond. *@paramconsumedtrueifthechildconsumedthefling,falseotherwise. *@returntrueifthenestedscrollingparentconsumedorotherwisereactedtothefling.*/publicbooleandispatchNestedFlingfloatvelocityX,floatvelocityY,bo177178179180181182183184185186187188189190191192193194195196oleanconsumed);bythisview.198.*199.*<p>Nestedpre-flingeventsaretonestedflingeventswhattouchinterceptistotouch200.*andwhatnestedpre-scrollistonestedscroll.<code>dispatchNestedPreFling</code>201.*offsetsanopportunityfortheparentviewinanestedflingtofullyconsumethefling202.*beforethechildviewconsumesit.Ifthismethodreturns<code>true</code>,anested203.*parentviewconsumedtheflingandthisviewshouldnotscrollasaresult.</p>204.*205.*<p>Forabetteruserexperienee,onlyoneviewinanestedscrollingchainshouldconsume206.*theflingatatime.Ifaparentviewconsumedtheflingthismethodwillreturnfalse.207.*Customviewimplementationsshouldaccountforthisintwoways:</p>208.*209.*<ul>210.* <li>Ifacustomviewispagedandneedstosettletoafixedpoint,donot211.* call<code>dispatchNestedPreFling</code>;consumetheflingandsettletoavalid212.* positionregardless.</li>213.* <li>Ifanestedparentdoesconsumethefling,thisviewshouldnotscrollatall,214.* eventosettlebacktoavalididleposition.</li>215.*</ul>216.*217.*<p>Viewsshouldalsonotofferflingvelocitiestonestedparentviewsalonganaxis218.*wherescrollingisnotcurrentlysupported;a{@linkandroid.widget.ScrollViewScrollview}219.*shouldnotofferahorizontalflingvelocitytoitsparentssincescrollingalongthat220.*axisisnotpermittedandcarryingvelocityalongthatmotiondoesnotmakesense.</p>221.*222.*@paramvelocityXHorizontalflingvelocityinpixelspersecond223.*@paramvelocityYVerticalflingvelocityinpixelspersecond224.*@returntrueifanestedscrollingparentconsumedthefling225.*/226.publicbooleandispatchNestedPreFlingfloatvelocityX,floatvelocityY)227.}有9個函數(shù)，簡單說明一下:setNestedScrollingEnabled實(shí)現(xiàn)該接口的View要調(diào)用setNestedScrollingEnabled(true)才可以使用嵌套滾動.2,isNestedScrollingEnabled判斷當(dāng)前view能否使用嵌套滾動.startNestedScroll和stopNestedScroll.是配對使用的.startNestedScroll表示view開始滾動了，一般是在ACTION_DOWN中調(diào)用，是來查找是否有嵌套處理的父View.在事件結(jié)束比如ACTION_UP或者ACTION_CANCLE中調(diào)用stopNestedScroll,告訴父布局滾動結(jié)束.4dispatchNestedPreScroll,在該view消費(fèi)滾動距離之前把總得滑動距離傳給父布局.dispatchNestedScroll,在該view消費(fèi)滾動距離之后，把剩下的滑動距離再次傳給父布局.dispatchNestedFling和dispatchNestedPreFling就是把view傳遞滑動的信息給父布局的.比如滑動速度NestedScrollingChildHelper這個類是一個輔助類就來把View的消息傳遞嵌套的父View。所以上面函數(shù)內(nèi)部實(shí)現(xiàn)基本上都是調(diào)用NestedScrollingChildHelper這類的函數(shù)，咱看一個：NestedScrollingChildHelper的startNestedScroll()函數(shù)，一般就是在NestedScrollingChild的startNestedScroll()函數(shù)里調(diào)用，參數(shù)表示方向，有兩個值ViewCompat.SCROLL_AXIS_HORIZONTAL,ViewCompat.SCROLL_AXIS_VERTICAL[java]viewplaincopy1.publicbooleanstartNestedScroll(intaxes){2.if(hasNestedScrollingParent()){3.//Alreadyinprogress2.if(hasNestedScrollingParent()){3.//Alreadyinprogress4.6.if(isNestedScrollingEnabled()){4.6.if(isNestedScrollingEnabled()){returntrue;5.7.8.Viewchild=mView;9.while(p!=null){10.if(ViewParentCompat.onStartNestedScroll(p,child,mView,ax4.15.es))axes);if7.8.Viewchild=mView;9.while(p!=null){10.if(ViewParentCompat.onStartNestedScroll(p,child,mView,ax4.15.es))axes);ifmNestedScrollingParent=p;ViewParentCompat.onNestedScrollAccepted(p,child,mView,returntrue;(pinstanceofView){ViewParentp=mView.getParent();16.16.18.p=p.getParent();19.child=(View)p;18.p=p.getParent();19.returnfalse;}上面就是尋找能夠響應(yīng)嵌套滑動的父View，也就是調(diào)用父類的onStartNestedScroll(),這個函數(shù)是NestedScrollingParent接口的函數(shù)，所以嵌套滑動的父View要實(shí)現(xiàn)這個接口，接著往下看，最后會有一個demo測試嵌套滑動接著來看NestedScrollingParent這個接口：[html]viewplaincopy1./*2.*Copyright(C)2015TheAndroidOpenSourceProject2.3.4.*LicensedundertheApacheLicense,Version2.0(the"License");4.5.*youmaynotusethisfileexceptincompliancewiththeLicense.6.*YoumayobtainacopyoftheLicenseat7.8./licenses/LICENSE-2.09.10.Unlessrequiredbyapplicablelaworagreedtoinwriting,software11.distributedundertheLicenseisdistributedonan"ASIS"BASIS,12.*WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.13.*SeetheLicenseforthespecificlanguagegoverningpermissionsand14.*limitationsundertheLicense.15.5.*youmaynotusethisfileexceptincompliancewiththeLicense.6.*YoumayobtainacopyoftheLicenseat7.8./licenses/LICENSE-2.09.10.Unlessrequiredbyapplicablelaworagreedtoinwriting,software11.distributedundertheLicenseisdistributedonan"ASIS"BASIS,12.*WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.13.*SeetheLicenseforthespecificlanguagegoverningpermissionsand14.*limitationsundertheLicense.15.*/18.packageandroid.support.v4.view;19.20.importandroid.view.MotionEvent;9.40.41.importandroid.view.VelocityTracker;importandroid.view.View;importandroid.view.ViewConfiguration;Thisinterfaceshouldbeimplementedby{@linkandroid.view.ViewGroupViewGroup}subclassesthatwishtosupportscrollingoperationsdelegatedbyanestedchildview.*<p>Classesimplementingthisinterfaceshouldcreateafinalinstanceofa{@linkNestedScrollingParentHelper}asafieldanddelegateanyVieworViewGroupmethodstothe<code>NestedScrollingParentHelper</code>methodsofthesamesignature.</p>*<p>Viewsinvokingnestedscrollingfunctionalityshouldalwaysdosofromtherelevant{@linkViewCompat},{@linkViewGroupCompat}or{@linkViewParentCompat}compatibilityshimstaticmethods.ThisensuresinteroperabilitywithnestedscrollingviewsonAndroid5.0Lollipopandnewer.</p>*/publicinterfaceNestedScrollingParent{/***Reacttoadescendantviewinitiatinganestablescrolloperation,claimingthe*nestedscrolloperationifappropriate.

0.61.<p>Thismethodwillbecalledinresponsetoadescendantviewinvoking{@linkViewCompat#startNestedScroll(View,int)}.Eachparentuptheviewhierarchywillbegivenanopportunitytorespondandclaimthenestedscrollingoperationbyreturning<code>true</code>.</p>*<p>ThismethodmaybeoverriddenbyViewParentimplementationstoindicatewhentheviewiswillingtosupportanestedscrollingoperationthatisabouttobegin.Ifitreturnstrue,thisViewParentwillbecomethetargetview'snestedscrollingparentforthedurationofthescrolloperationinprogress.WhenthenestedscrollisfinishedthisViewParentwillreceiveacallto{@link#onStopNestedScroll(View)}.</p>*@paramchildDirectchildofthisViewParentcontainingtarget@paramtargetViewthatinitiatedthenestedscroll@paramnestedScrollAxesFlagsconsistingof{@linkViewCompat#SCROLL_AXIS_HORIZONTAL},{@linkViewCompat#SCROLL_AXIS_VERTICAL}orboth@returntrueifthisViewParentacceptsthenestedscrolloperation*/publicbooleanonStartNestedScroll(Viewchild,Viewtarget,intnestedScrollAxes);

3.84./ Reacttoanestedscrolloperationending.* Reacttoanestedscrolloperationending.**<p>Performcleanupafteranestedscrollingoperation.Reacttothesuccessfulclaimingofanestedscrolloperation.*<p>Thismethodwillbecalledafter{@link#onStartNestedScroll(View,View,int)onStartNestedScroll}returnstrue.Itoffersanopportunityfortheviewanditssuperclassestoperforminitialconfigurationforthenestedscroll.Implementationsofthismethodshouldalwayscalltheirsuperclass'simplementationofthismethodifoneispresent.</p>*@paramchildDirectchildofthisViewParentcontainingtarget@paramtargetViewthatinitiatedthenestedscroll@paramnestedScrollAxesFlagsconsistingof{@linkViewCompat#SCROLL_AXIS_HORIZONTAL},{@linkViewCompat#SCROLL_AXIS_VERTICAL}orboth@see#onStartNestedScroll(View,View,int)@see#onStopNestedScroll(View)*/publicvoidonNestedScrollAccepted(Viewchild,Viewtarget,intnestedScrollAxes);

00101102103104105Thismethodwillbecalledwhenanestedscrollstops,forexamplewhenanestedtouchscrollendswitha{@linkMotionEvent#ACTION_UP}or{@linkMotionEvent#ACTION_CANCEL}event.Implementationsofthismethodshouldalwayscalltheirsuperclass'simplementationofthismethodifoneispresent.</p>*@paramtargetViewthatinitiatedthenestedscroll*/publicvoidonStopNestedScroll(Viewtarget);/**Reacttoanestedscrollinprogress.*<p>ThismethodwillbecalledwhentheViewParent'scurrentnestedscrollingchildviewdispatchesanestedscrollevent.ToreceivecallstothismethodtheViewParentmusthavepreviouslyreturned<code>true</code>foracallto, *{@link#onStartNestedScroll(View,View,int)}.</p>*, *<p>Boththeconsumedandunconsumedportionsofthescrolldistancearereportedtothe, *ViewParent.Animplementationmaychoosetousetheconsumedportiontomatchorchasescroll, *positionofmultiplechildelements,forexample.Theunconsumedportionmaybeusedto, *allowcontinuousdraggingofmultiplescrollingordraggableelements,suchasscrolling

106107108109110111112113114115116117118119120121122123124125, *alistwithinaverticaldrawerwherethedrawerbeginsdraggingoneetheedgeofinnerscrollingeontentisreached.</p>*, *@paramtargetThedescendentviewcontrollingthenestedscroll, *@paramdxConsumedHorizontalscrolldistanceinpixelsalreadyconsumedbytarget, *@paramdyConsumedVerticalscrolldistanceinpixelsalreadyconsumedbytarget, *@paramdxUnconsumedHorizontalscrolldistanceinpixelsnotconsumedbytarget, *@paramdyUnconsumedVerticalscrolldistanceinpixelsnotconsumedbytarget*/,publicvoidonNestedScroll(Viewtarget,intdxConsumed,intdyConsumed,, intdxUnconsumed,intdyUnconsumed);/**, *Reacttoanestedscrollinprogressbeforethetargetviewconsumesaportionofthescroll.*, *<p>Whenworkingwithnestedscrollingoftentheparentviewmaywantanopportunity, *toconsumethescrollbeforethenestedscrollingchilddoes.Anexampleofthisisa, *drawerthatcontainsascrollablelist.Theuserwillwanttobeabletoscrollthelist*fullyintoviewbeforethelistitselfbeginsscrolling.</p>

{@linkVelocityTrackervelocity}inthedirectionofscrollingthat<p><code>onNestedPreScroll</code>iscalledwhenanestedscrollingchildinvokes{@linkVelocityTrackervelocity}inthedirectionofscrollingthat*{@linkView#dispatchNestedPreScroll(int,int,int[],int[])}.Theimplementationshould*reporthowanypixelsofthescrollreportedbydx,dywereconsumedinthe*<code>consumed</code>array.Index0correspondstodxandindex1correspondstody.*Thisparameterwillneverbenull.Initialvaluesforconsumed[0]andconsumed[1]* willalwaysbe0.</p>**@paramtargetViewthatinitiatedthenestedscroll* @param dx Horizontalscroll distancein pixels* @param dy Verticalscroll distance inpixels*@paramconsumedOutput.ThehorizontalandverticalscrolldistanceconsumedbythisparentTOC\o"1-5"\h\z*/publicvoidonNestedPreScroll(Viewtarget,intdx,intdy,int[]consumed);139./meetsorexceedsmeetsorexceeds*Requestaflingfromanestedscroll.*144.145.*<p>Thismethodsignifiesthatanestedscrollingchildhasdetectedsuitableconditions144.145.*forafling.Generallythismeansthatatouchscrollhasendedwith

146147148149150151152153154155156157158159160161162163164165, *the{@linkViewConfiguration#getScaledMinimumFlingVelocity()minimumflingvelocity}alongascrollableaxis.</p>*, *<p>Ifanestedscrollingchildviewwouldnormallyflingbutitisattheedgeof, *itsowncontent,itcanusethismethodtodelegatetheflingtoitsnestedscrolling, *parentinstead.Theparentmayoptionallyconsumetheflingorobserveachildfling.</p>*, *@paramtargetViewthatinitiatedthenestedscroll, *@paramvelocityXHorizontalvelocityinpixelspersecond, *@paramvelocityYVerticalvelocityinpixelspersecond, *@paramconsumedtrueifthechildconsumedthefling,falseotherwise, *@returntrueifthisparentconsumedorotherwisereactedtothefling*/,publicbooleanonNestedFling(Viewtarget,floatvelocityX,floatvelocityY,booleanconsumed);/**, *Reacttoanestedflingbeforethetargetviewconsumesit.*, *<p>Thismethodsiginfiesthatanestedscrollingchildhasdetectedaflingwiththegiven, *velocityalongeachaxis.Generallythismeansthatatouchscrollhasendedwitha

166.*{@linkVelocityTrackervelocity}inthedirectionofscrollingthatmeetsorexceeds167.*the{@linkViewConfiguration#getScaledMinimumFlingVelocity()minimumflingvelocity}168.*alongascrollableaxis.</p>169.*170.*<p>Ifanestedscrollingparentisconsumingmotionaspartofa171.*{@link#onNestedPreScroll(View,int,int,int[])pre-scroll},itmaybeappropriatefor172.*ittoalsoconsumethepre-flingtocompletethatsamemotion.Byreturning173.*<code>true</code>fromthismethod,theparentindicatesthatthechildshouldnot174.*flingitsowninternalcontentaswell.</p>175.*176.*@paramtargetViewthatinitiatedthenestedscroll177.*@paramvelocityXHorizontalvelocityinpixelspersecond178.*@paramvelocityYVerticalvelocityinpixelspersecond179.*@returntrueifthisparentconsumedtheflingaheadofthetargetview180.*/181.publicbooleanonNestedPreFling(Viewtarget,floatvelocityX,floatvelocityY);182.183./**184.*ReturnthecurrentaxesofnestedscrollingforthisNestedScrollingParent.185.*186.*<p>ANestedScrollingParentreturningsomethingotherthan{@linkViewCompat#SCROLL_AXIS_NONE}

*iscurrentlyactingasanestedscrollingparentforoneormoredescendantviewsin*thehierarchy.</p>**@returnFlagsindicatingthecurrentaxesofnestedscrolling* @see ViewCompat#SCROLL_AXIS_HORIZONTAL* @see ViewCompat#SCROLL_AXIS_VERTICAL* @see ViewCompat#SCROLL_AXIS_NONE*/publicintgetNestedScrollAxes();}8個函數(shù)，簡單介紹一下：l,onStartNestedScroll.當(dāng)子view的調(diào)用NestedScrollingChild的方法startNestedScroll時，會調(diào)用該方法.前面分析到了2,onNestedScrollAccepted.如果onStartNestedScroll方法返回的是true的話,那么緊接著就會調(diào)用該方法.它是讓嵌套滾動在開始滾動之前，讓布局容器(viewGroup)或者它的父類執(zhí)行一些配置的初始化的.3,onStopNestedScroll停止?jié)L動了，當(dāng)子view調(diào)用stopNestedScroll時會調(diào)用該方法.4,onNestedScroll,當(dāng)子view調(diào)用dispatchNestedScroll方法時，會調(diào)用該方法.5,onNestedPreScroll,當(dāng)子view調(diào)用dispatchNestedPreScroll方法是，會調(diào)用該方法.6,dispatchNestedFling和