对Android近期任务列表Recent Applications的简单分析Word下载.docx
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mIcons）{
25icon.setCompoundDrawables（null,null,null,null）;
26icon.setTag（null）;
27}
28}
29};
30
31publicRecentApplicationsDialog（Contextcontext）{
32super（context,com.android.internal.R.style.Theme_Dialog_RecentApplications）;
33
34}
35
36/**
37*Wecreatetherecentapplicationsdialogjustonce,anditstaysaround（hidden）
38*untilactivatedbytheuser.
39*
40*@seePhoneWindowManager#showRecentAppsDialog
41*/
42@Override
43protectedvoidonCreate（BundlesavedInstanceState）{
44super.onCreate（savedInstanceState）;
45
46Contextcontext=getContext（）;
47
48if（sStatusBar==null）{
49sStatusBar=（StatusBarManager）context.getSystemService（Context.STATUS_BAR_SERVICE）;
50}
51
52Windowwindow=getWindow（）;
53window.requestFeature（Window.FEATURE_NO_TITLE）;
54window.setType（WindowManager.LayoutParams.TYPE_SYSTEM_DIALOG）;
55window.setFlags（WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM,
56WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM）;
57window.setTitle（"
Recents"
）;
58
59setContentView（com.android.internal.R.layout.recent_apps_dialog）;
60
61finalWindowManager.LayoutParamsparams=window.getAttributes（）;
62params.width=WindowManager.LayoutParams.MATCH_PARENT;
63params.height=WindowManager.LayoutParams.MATCH_PARENT;
64window.setAttributes（params）;
65window.setFlags（0,WindowManager.LayoutParams.FLAG_DIM_BEHIND）;
66
67//默认显示8个
68mIcons[0]=（TextView）findViewById（com.android.internal.R.id.button0）;
69mIcons[1]=（TextView）findViewById（com.android.internal.R.id.button1）;
70mIcons[2]=（TextView）findViewById（com.android.internal.R.id.button2）;
71mIcons[3]=（TextView）findViewById（com.android.internal.R.id.button3）;
72mIcons[4]=（TextView）findViewById（com.android.internal.R.id.button4）;
73mIcons[5]=（TextView）findViewById（com.android.internal.R.id.button5）;
74mIcons[6]=（TextView）findViewById（com.android.internal.R.id.button6）;
75mIcons[7]=（TextView）findViewById（com.android.internal.R.id.button7）;
76mNoAppsText=findViewById（com.android.internal.R.id.no_applications_message）;
77
78//关键在哪，你懂得...
79for（TextViewb:
80b.setOnClickListener（this）;
81}
82}
83
84@Override
85publicbooleanonKeyDown（intkeyCode,KeyEventevent）{
86if（keyCode==KeyEvent.KEYCODE_TAB）{
87//IgnoreallmetakeysotherthanSHIFT.Theappswitchkeycouldbea
88//fallbackactionchordedwithALT,METAorevenCTRLdependingonthekeymap.
89//DPadnavigationishandledbytheViewRootelsewhere.
90finalbooleanbackward=event.isShiftPressed（）;
91finalintnumIcons=mIcons.length;
92intnumButtons=0;
93while（numButtons<
numIcons&
&
mIcons[numButtons].getVisibility（）==View.VISIBLE）{
94numButtons+=1;
95}
96if（numButtons!
=0）{
97intnextFocus=backward?
numButtons-1:
0;
98for（inti=0;
i<
numButtons;
i++）{
99if（mIcons[i].hasFocus（））{
100if（backward）{
101nextFocus=（i+numButtons-1）%numButtons;
102}else{
103nextFocus=（i+1）%numButtons;
104}
105break;
106}
107}
108finalintdirection=backward?
View.FOCUS_BACKWARD:
View.FOCUS_FORWARD;
109if（mIcons[nextFocus].requestFocus（direction））{
110mIcons[nextFocus].playSoundEffect（
111SoundEffectConstants.getContantForFocusDirection（direction））;
112}
113}
114
115//ThedialogalwayshandlesthekeytopreventtheViewRootfrom
116//performingthedefaultnavigationitself.
117returntrue;
118}
119
120returnsuper.onKeyDown（keyCode,event）;
121}
122
123/**
124*Dismissthedialogandswitchtotheselectedapplication.
125*/
126publicvoiddismissAndSwitch（）{
127finalintnumIcons=mIcons.length;
128RecentTagtag=null;
129for（inti=0;
numIcons;
130if（mIcons[i].getVisibility（）!
=View.VISIBLE）{
131break;
132}
133if（i==0||mIcons[i].hasFocus（））{
134tag=（RecentTag）mIcons[i].getTag（）;
135if（mIcons[i].hasFocus（））{
136break;
137}
138}
139}
140if（tag!
=null）{
141switchTo（tag）;
142}
143dismiss（）;
144}
145
146/**
147*Handlerforuserclicks.Ifabuttonwasclicked,launchthecorrespondingactivity.
148*/
149publicvoidonClick（Viewv）{
150for（TextViewb:
151if（b==v）{
152RecentTagtag=（RecentTag）b.getTag（）;
153switchTo（tag）;
154break;
155}
156}
157dismiss（）;
158}
159
160//
161privatevoidswitchTo（RecentTagtag）{
162if（tag.info.id>
163//Thisisanactivetask;
itshouldjustgototheforeground.
164finalActivityManageram=（ActivityManager）
165getContext（）.getSystemService（Context.ACTIVITY_SERVICE）;
166am.moveTaskToFront（tag.info.id,ActivityManager.MOVE_TASK_WITH_HOME）;
167}elseif（tag.intent!
168tag.intent.addFlags（Intent.FLAG_ACTIVITY_LAUNCHED_FROM_HISTORY
169|Intent.FLAG_ACTIVITY_TASK_ON_HOME）;
170try{
171getContext（）.startActivity（tag.intent）;
172}catch（ActivityNotFoundExceptione）{
173Log.w（"
Recent"
"
Unabletolaunchrecenttask"
e）;
174}
175}
176}
177
178/**
179*Setupandshowtherecentactivitiesdialog.
180*/
181@Override
182publicvoidonStart（）{
183super.onStart（）;
184reloadButtons（）;
185if（sStatusBar!
186sStatusBar.disable（StatusBarManager.DISABLE_EXPAND）;
187}
188
189//receivebroadcasts
190getContext（）.registerReceiver（mBroadcastReceiver,mBroadcastIntentFilter）;
191
192mHandler.removeCallbacks（mCleanup）;
193}
194
195/**
196*Dismisstherecentactivitiesdialog.
197*/
198@Override
199publicvoidonStop（）{
200super.onStop（）;
201
202if（sStatusBar!
203sStatusBar.disable（StatusBarManager.DISABLE_NONE）;
204}
205
206//stopreceivingbroadcasts
207getContext（）.unregisterReceiver（mBroadcastReceiver）;
208
209mHandler.postDelayed（mCleanup,100）;
210}
211
212/**
213*Reloadthe6buttonswithrecentactivities
214*/
215privatevoidreloadButtons（）{
216
217finalContextcontext=getContext（）;
218finalPackageManagerpm=context.getPackageManager（）;
219finalActivityManageram=（ActivityManager）
220context.getSystemService（Context.ACTIVITY_SERVICE）;
221finalList<
ActivityManager.RecentTaskInfo>
recentTasks=
222am.getRecentTasks（MAX_RECENT_TASKS,ActivityManager.RECENT_IGNORE_UNAVAILABLE）;
223
224ActivityInfohomeInfo=
225newIntent（Intent.ACTION_MAIN）.addCategory（Intent.CATEGORY_HOME）
226.resolveActivityInfo（pm,0）;
227
228IconUtilitiesiconUtilities=newIconUtilities（getContext（））;
229
230//Performancenote:
OurandroidperformanceguidesaystopreferIteratorwhen
231//usingaListclass,butbecauseweknowthatgetRecentTasks（）alwaysreturns
232//anArrayList<
>
we'
lluseasimpleindexinstead.
233intindex=0;
234intnumTasks=recentTasks.size（）;
235for（inti=0;
numTasks&
（index<
NUM_BUTTONS）;
++i）{
236finalActivityManager.RecentTaskInfoinfo=recentTasks.get（i）;
237
238//fordebugpurposesonly,disallowfirstresulttocreateemptylists
239if（DBG_FORCE_EMPTY_LIST&
（i==0））continue;
240
241Intentintent=newIntent（info.baseIntent）;
242if（info.origActivity!
243intent.setComponent（info.origActivity）;
244}
245
246//Skipthecurrenthomeactivity.
247if（homeInfo!
248if（homeInfo.packageName.equals（
249intent.getComponent（）.getPackageName（））
250&
homeInfo.name.equals（
251intent.getComponent（）.getClassName（）））{
252continue;
253}
254}
255
256intent.setFlags（（intent.getFlags（）&
~Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED）
257|Intent.FLAG_ACTIVITY_NEW_TASK）;
258finalResolveInforesolveInfo=pm.resolveActivity（intent,0）;
259if（resolveInfo!
260finalActivityInfoactivityInfo=resolveInfo.activityInfo;
261finalStringtitle=activityInfo.loadLabel（pm）.toString（）;
262Drawableicon=activityInfo.loadIcon（pm）;
263
264if（title!
=null&
title.length（）>
0&
icon!
265finalTextViewtv=mIcons[index];
266tv.setText（title）;
267icon=iconUtilities.createIconDrawable（icon）;
268tv.setCompoundDrawables（null,icon,null,null）;
269RecentTagtag=newRecentTag（）;
270tag.info=info;
271tag.intent=intent;
272tv.setTag（tag）;
273tv.setVisibility（View.VISIBLE）;
274tv.setPressed（false）;
275tv.clearFocus（）;
276++index;
277}
278}
279}
280
281//handlethecaseof"
noiconstoshow"
282mNoAppsText.setVisibility（（index==0）?
View.VISIBLE:
View.GONE）;
283
284//hidetherest
285for（;
index<
NUM_BUTTONS;
++index）{
286mIcons[index].setVisibility（View.GONE）;
287}
288}
289
290/**
291*ThisisthelistenerfortheACTION_CLOSE_SYSTEM_DIALOGSintent.I
升级会员 