android:Handler整理總結(jié)當(dāng)我們在處理下載或是其他需要長時間執(zhí)行的任務(wù)時，如果直接把處理函數(shù)放Activity的OnCreate或是OnStart中，會導(dǎo)致執(zhí)行過程中整個Activity無響應(yīng)，如果時間過長，程序還會掛掉。Handler就是把這些功能放到一個單獨(dú)的線程里執(zhí)行，與Activity互不影響。我們簡單用例子來說明：小實(shí)例一：5秒鐘更新一下Title（標(biāo)題），如圖：代碼如下：viewplaincopytoclipboardprint?packagecom.android.tutor;importjava.util.Timer;importjava.util.TimerTask;importandroid.app.Activity;importandroid.os.Bundle;importandroid.os.Handler;importandroid.os.Message;publicclassHandlerDemoextendsActivity{//title為setTitle方法提供變量,這里為了方便我設(shè)置成了int型privateinttitle=0;privateHandlermHandler=newHandler(){publicvoidhandleMessage(Messagemsg){switch(msg.what){case1:updateTitle();break;}};};publicvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);Timertimer=newTimer();timer.scheduleAtFixedRate(newMyTask(),1,5000);}privateclassMyTaskextendsTimerTask{@Overridepublicvoidrun(){Messagemessage=newMessage();message.what=1;mHandler.sendMessage(message);}}publicvoidupdateTitle(){setTitle("WelcometoMrWei'sblog"+title);title++;}}packagecom.android.tutor;importjava.util.Timer;importjava.util.TimerTask;importandroid.app.Activity;importandroid.os.Bundle;importandroid.os.Handler;importandroid.os.Message;publicclassHandlerDemoextendsActivity{ //title為setTitle方法提供變量,這里為了方便我設(shè)置成了int型 privateinttitle=0; privateHandlermHandler=newHandler(){ publicvoidhandleMessage(Messagemsg){ switch(msg.what){ case1: updateTitle(); break; } }; }; publicvoidonCreate(BundlesavedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.main); Timertimer=newTimer(); timer.scheduleAtFixedRate(newMyTask(),1,5000); } privateclassMyTaskextendsTimerTask{ @Override publicvoidrun(){ Messagemessage=newMessage(); message.what=1; mHandler.sendMessage(message); } } publicvoidupdateTitle(){ setTitle("WelcometoMrWei'sblog"+title); title++; }}小實(shí)例二：用Handler更新進(jìn)度條ProgressBar；如圖：當(dāng)按開始按鈕時，進(jìn)度條會每隔500毫秒加1,直到加到100或者按停止時停止代碼：viewplaincopytoclipboardprint?importandroid.app.Activity;importandroid.os.Bundle;importandroid.os.Handler;importandroid.view.View;importandroid.view.View.OnClickListener;importandroid.widget.Button;importandroid.widget.ProgressBar;publicclassmainextendsActivity{/**Calledwhentheactivityisfirstcreated.*/ProgressBarpb1;Handlerhandle=newHandler();//新建一個Handler對象Buttonb1;Buttonb2;@OverridepublicvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);pb1=(ProgressBar)findViewById(R.id.pb1);pb1.setProgress(0);b1=(Button)findViewById(R.id.b1);b1.setOnClickListener(b1Lis);b2=(Button)findViewById(R.id.b2);b2.setOnClickListener(b2Lis);}privateOnClickListenerb1Lis=newOnClickListener(){@OverridepublicvoidonClick(Viewv){//TODOAuto-generatedmethodstubhandle.post(add);//開始執(zhí)行add}};privateOnClickListenerb2Lis=newOnClickListener(){@OverridepublicvoidonClick(Viewv){//TODOAuto-generatedmethodstubhandle.removeCallbacks(add);//停止執(zhí)行pb1.setProgress(0);}};intpro=0;Runnableadd=newRunnable(){//定義add@Overridepublicvoidrun(){//TODOAuto-generatedmethodstubpro=pb1.getProgress()+1;pb1.setProgress(pro);setTitle(String.valueOf(pro));if(pro<100){handle.postDelayed(add,500);//如果進(jìn)度小于100,，則延遲500毫秒后重復(fù)執(zhí)行add}}};}importandroid.app.Activity;importandroid.os.Bundle;importandroid.os.Handler;importandroid.view.View;importandroid.view.View.OnClickListener;importandroid.widget.Button;importandroid.widget.ProgressBar;publicclassmainextendsActivity{ /**Calledwhentheactivityisfirstcreated.*/ ProgressBarpb1; Handlerhandle=newHandler(); //新建一個Handler對象 Buttonb1; Buttonb2; @Override publicvoidonCreate(BundlesavedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.main); pb1=(ProgressBar)findViewById(R.id.pb1); pb1.setProgress(0); b1=(Button)findViewById(R.id.b1); b1.setOnClickListener(b1Lis); b2=(Button)findViewById(R.id.b2); b2.setOnClickListener(b2Lis); } privateOnClickListenerb1Lis=newOnClickListener(){ @Override publicvoidonClick(Viewv){ //TODOAuto-generatedmethodstub handle.post(add); //開始執(zhí)行add } }; privateOnClickListenerb2Lis=newOnClickListener(){ @Override publicvoidonClick(Viewv){ //TODOAuto-generatedmethodstub handle.removeCallbacks(add); //停止執(zhí)行 pb1.setProgress(0); } }; intpro=0; Runnable