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1、word对Android近期任务列表（Recent Applications）的简单分析分类：Android开发2013-12-31 11:061599人阅读评论(0)收藏举报这里的近期任务列表就是长按Home键出来的那个Dialog，里面放着近期打开过的应用，当然3.0以上系统的多任务切换键也是。这个Dialog的实现在Android源码的中。接下来就对这个源码分析一下。javaview plaincopy1. publicclassRecentApplicationsDialogextendsDialogimplementsOnClickListener2. /Elementsfordeb
2、uggingsupport3. /privatestaticfinalStringLOG_TAG=RecentApplicationsDialog;4. privatestaticfinalbooleanDBG_FORCE_EMPTY_LIST=false;5. 6. staticprivateStatusBarManagersStatusBar;7. 8. privatestaticfinalintNUM_BUTTONS=8;9. privatestaticfinalintMAX_RECENT_TASKS=NUM_BUTTONS*2;/allowforsomediscards10. 11.
3、finalTextViewmIcons=newTextViewNUM_BUTTONS;12. ViewmNoAppsText;13. IntentFiltermBroadcastIntentFilter=newIntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);14. 15. classRecentTag16. ActivityManager.RecentTaskInfoinfo;17. Intentintent;18. 19. 20. HandlermHandler=newHandler();21. RunnablemCleanup=newRun
4、nable()22. publicvoidrun()23. /dumpextramemorywerehangingonto24. for(TextViewicon:mIcons)25. icon.setpoundDrawables(null,null,null,null);26. icon.setTag(null);27. 28. 29. ;30. 31. publicRecentApplicationsDialog(Contextcontext)32. super(context,.android.internal.R.style.Theme_Dialog_RecentApplication
5、s);33. 34. 35. 36. /*37. *Wecreatetherecentapplicationsdialogjustonce,anditstaysaround(hidden)38. *untilactivatedbytheuser.39. *40. *seePhoneWindowManager#showRecentAppsDialog41. */42. Override43. protectedvoidonCreate(BundlesavedInstanceState)44. super.onCreate(savedInstanceState);45. 46. Contextco
6、ntext=getContext();47. 48. if(sStatusBar=null)49. sStatusBar=(StatusBarManager)context.getSystemService(Context.STATUS_BAR_SERVICE);50. 51. 52. Windowwindow=getWindow();53. window.requestFeature(Window.FEATURE_NO_TITLE);54. window.setType(WindowManager.LayoutParams.TYPE_SYSTEM_DIALOG);55. window.set
7、Flags(WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM,56. WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);57. window.setTitle(Recents);58. 59. setContentView(.android.internal.R.layout.recent_apps_dialog);60. 61. finalWindowManager.LayoutParamsparams=window.getAttributes();62. params.width=Window
8、Manager.LayoutParams.MATCH_PARENT;63. params.height=WindowManager.LayoutParams.MATCH_PARENT;64. window.setAttributes(params);65. window.setFlags(0,WindowManager.LayoutParams.FLAG_DIM_BEHIND);66. 67. /默认显示8个68. mIcons0=(TextView)findViewById(.android.internal.R.id.button0);69. mIcons1=(TextView)findV
9、iewById(.android.internal.R.id.button1);70. mIcons2=(TextView)findViewById(.android.internal.R.id.button2);71. mIcons3=(TextView)findViewById(.android.internal.R.id.button3);72. mIcons4=(TextView)findViewById(.android.internal.R.id.button4);73. mIcons5=(TextView)findViewById(.android.internal.R.id.b
10、utton5);74. mIcons6=(TextView)findViewById(.android.internal.R.id.button6);75. mIcons7=(TextView)findViewById(.android.internal.R.id.button7);76. mNoAppsText=findViewById(.android.internal.R.id.no_applications_message);77. 78. /关键在哪，你懂得.79. for(TextViewb:mIcons)80. b.setOnClickListener(this);81. 82.
11、 83. 84. Override85. publicbooleanonKeyDown(intkeyCode,KeyEventevent)86. if(keyCode=KeyEvent.KEYCODE_TAB)87. /IgnoreallmetakeysotherthanSHIFT.Theappswitchkeycouldbea88. /fallbackactionchordedwithALT,METAorevenCTRLdependingonthekeymap.89. /DPadnavigationishandledbytheViewRootelsewhere.90. finalboolea
12、nbackward=event.isShiftPressed();91. finalintnumIcons=mIcons.length;92. intnumButtons=0;93. while(numButtonsnumIcons&mIconsnumButtons.getVisibility()=View.VISIBLE)94. numButtons+=1;95. 96. if(numButtons!=0)97. intnextFocus=backward?numButtons-1:0;98. for(inti=0;inumButtons;i+)99. if(mIconsi.hasFocus(
