Android-- Launcher拖拽事件详解

痛定思痛。 2022-03-17 10:09 410阅读 0赞

分享一下我老师大神的人工智能教程。零基础！通俗易懂！风趣幽默！还带黄段子！希望你也加入到我们人工智能的队伍中来！[https://blog.csdn.net/jiangjunshow][https_blog.csdn.net_jiangjunshow]

转自：

[http://blog.csdn.net/wdaming1986/article/details/7585649][http_blog.csdn.net_wdaming1986_article_details_7585649]

[http://blog.csdn.net/wdaming1986/article/details/7671318][http_blog.csdn.net_wdaming1986_article_details_7671318]

最近研究ICS4.0的Launcher，发现4.0和2.3有稍微点区别，但是区别不是特别大，所以我就先整理一下Launcher启动的大致流程。Launcher其实是贯彻于手机的整个系统的，时时刻刻都在运行，要是Launcher不运行了，手机就得黑屏了。Launcher的LauncherMode=singletask，所以说不管Launcher启动了哪个应用，总有个Launcher的实例在堆栈中，并且位于栈底。点击[Home键][Home]进入到Launcher，上篇[Android的全局键（home键/长按耳机键）详解【android源码解析八】][Android_home_android]中有详细的介绍。大致思路其实就是启动launcher的时候，新启动一个task。大致先说这么多，先看截图：

大明原创，转载请标明出处：[http://blog.csdn.net/wdaming1986/article/details/7585649][http_blog.csdn.net_wdaming1986_article_details_7585649]

![1337478073_9125.png][]

图（1）

上图是4.0的Launcher界面，下面我们分步来解析一下Launcher的启动过程。

Step 0：首先要给大家介绍一下Launcher的数据库，这个数据库中存放着待机界面的图标，主屏底部的应用程序图标和桌面folder中各应用程序的图标，ICS4.0的folder中只能放应用程序的快捷方式，shortcut不能放到这个folder中，先看截图：

![1337520386_7883.PNG][]

图（2）

说说各字段的含义：

title：表示桌面应用程序的名字，有的title为空，表示是widget的快捷方式；

intent：表示启动这个图标的intent放到数据库中，当click的时候就会调用这个字段，启动相应的应用程序；

container：表示应用程序的容器，folder的容器为整数，-100：表示在桌面的程序，-101：表示是主屏底部的程序；

screen：表示在第几个屏，folder的screen都是0, container=-101的为0,1,3,4；2为allapp的按钮；

cellX：表示在屏幕X轴的位置，（0,1,2,3），左上角为0点，往右依次增加；

cellY：表示在屏幕Y轴的位置，（0,1,2,3），左上角为0点，往下依次增加；

spallX：表示占X轴几个格；

spallY：表示占Y轴几个格；

itemType：应用程序用0表示，shortcut用1表示，folder用2表示，widget用4表示；

appWidgetId：-1表示不是widget，数字大于0表示才是widget；

isShortCut：值为0表示不是应用程序的ShortCut，值为1表示是应用程序的ShortCut；

iconType：值为0表示图标的名字被定义为包名的资源id，值为1表示图标用bitmap保存；

icon：表示应用程序的图标，二进制的；显示为一张图片；

说明：**folder中的应用快捷方式绑定folder---->是用container的值绑定folder的id的；**

详细的讲解请参考LauncherSettings.java这个类，有数据库字段的详细讲解；

手机是在第一次烧机完成后，数据库的值还没有，这时候launcher解析default\_workspace.xml把这个值存到数据库中；所以说想定制什么样的开机桌面就在default\_workspace.xml中做相应的配置，具体参照我前面的博客：

[Android中源码Launcher主屏幕程序排列详解【安卓Launcher进化一】][Android_Launcher_Launcher]中有详细的介绍：

i f (!convertDatabase(db)) \{  
// Populate favorites table with initial favorites  
loadFavorites(db, R.xml.default\_workspace);  
\}

Step 1：开机后先启动LauncherApplication.java这个类的onCreate（）方法，下面看代码：

**\[java\]** [view plain][] [copy][view plain] [print][view plain] [?][view plain]

1.  @Override
2.  public void onCreate() \{
3.  super.onCreate();
4.  
5.  // set sIsScreenXLarge and sScreenDensity \*before\* creating icon cache
6.  // 在创建图标缓存之前先设置sIsScreenXLarge和屏幕设备的分辨率
7.  final int screenSize = getResources().getConfiguration().screenLayout &
8.  Configuration.SCREENLAYOUT\_SIZE\_MASK;
9.  sIsScreenLarge = screenSize == Configuration.SCREENLAYOUT\_SIZE\_LARGE ||
10. screenSize == Configuration.SCREENLAYOUT\_SIZE\_XLARGE;
11. sScreenDensity = getResources().getDisplayMetrics().density;
12. 
13. // 实例化图标缓存区的对象
14. mIconCache = new IconCache(this);
15. // 实例化一个LauncherModel对象，这个类是保存Launcher的内存启动状态，更新Launcher的数据库的作用
16. mModel = new LauncherModel(this, mIconCache);
17. 
18. // Register intent receivers
19. // 注册监听，应用package增加，删除，改变的监听。
20. IntentFilter filter = new IntentFilter(Intent.ACTION\_PACKAGE\_ADDED);
21. filter.addAction(Intent.ACTION\_PACKAGE\_REMOVED);
22. filter.addAction(Intent.ACTION\_PACKAGE\_CHANGED);
23. filter.addDataScheme("package");
24. registerReceiver(mModel, filter);
25. filter = new IntentFilter();
26. // 注册application是否可用，语言改变，方向改变的监听。4.0支持横竖屏
27. filter.addAction(Intent.ACTION\_EXTERNAL\_APPLICATIONS\_AVAILABLE);
28. filter.addAction(Intent.ACTION\_EXTERNAL\_APPLICATIONS\_UNAVAILABLE);
29. filter.addAction(Intent.ACTION\_LOCALE\_CHANGED);
30. filter.addAction(Intent.ACTION\_CONFIGURATION\_CHANGED);
31. registerReceiver(mModel, filter);
32. filter = new IntentFilter();
33. filter.addAction(SearchManager.INTENT\_GLOBAL\_SEARCH\_ACTIVITY\_CHANGED);
34. registerReceiver(mModel, filter);
35. filter = new IntentFilter();
36. filter.addAction(SearchManager.INTENT\_ACTION\_SEARCHABLES\_CHANGED);
37. registerReceiver(mModel, filter);
38. 
39. // Register for changes to the favorites
40. // 注册favorites应用程序数据库改变的监听
41. ContentResolver resolver = getContentResolver();
42. resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT\_URI,true,
43. mFavoritesObserver);
44. \}

@Override    public void onCreate() {        super.onCreate();        // set sIsScreenXLarge and sScreenDensity *before* creating icon cache        // 在创建图标缓存之前先设置sIsScreenXLarge和屏幕设备的分辨率        final int screenSize = getResources().getConfiguration().screenLayout &                Configuration.SCREENLAYOUT_SIZE_MASK;        sIsScreenLarge = screenSize == Configuration.SCREENLAYOUT_SIZE_LARGE ||            screenSize == Configuration.SCREENLAYOUT_SIZE_XLARGE;        sScreenDensity = getResources().getDisplayMetrics().density;        // 实例化图标缓存区的对象        mIconCache = new IconCache(this);        // 实例化一个LauncherModel对象，这个类是保存Launcher的内存启动状态，更新Launcher的数据库的作用        mModel = new LauncherModel(this, mIconCache);        // Register intent receivers        // 注册监听，应用package增加，删除，改变的监听。        IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);        filter.addAction(Intent.ACTION_PACKAGE_REMOVED);        filter.addAction(Intent.ACTION_PACKAGE_CHANGED);        filter.addDataScheme("package");        registerReceiver(mModel, filter);        filter = new IntentFilter();        // 注册application是否可用，语言改变，方向改变的监听。4.0支持横竖屏        filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);        filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);        filter.addAction(Intent.ACTION_LOCALE_CHANGED);        filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);        registerReceiver(mModel, filter);        filter = new IntentFilter();        filter.addAction(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED);        registerReceiver(mModel, filter);        filter = new IntentFilter();        filter.addAction(SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED);        registerReceiver(mModel, filter);        // Register for changes to the favorites        // 注册favorites应用程序数据库改变的监听        ContentResolver resolver = getContentResolver();        resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT_URI, true,                mFavoritesObserver);    }

Step 2：在LauncherApplication.java中onTerminate（）的方法，解除监听的绑定；

**\[java\]** [view plain][] [copy][view plain] [print][view plain] [?][view plain]

1.  /\*\*
2.   \* There's no guarantee that this function is ever called.
3.   \*/
4.  @Override
5.  public void onTerminate() \{
6.  super.onTerminate();
7.  
8.  unregisterReceiver(mModel);
9.  
10. ContentResolver resolver = getContentResolver();
11. resolver.unregisterContentObserver(mFavoritesObserver);
12. \}

/**     * There's no guarantee that this function is ever called.     */    @Override    public void onTerminate() {        super.onTerminate();        unregisterReceiver(mModel);        ContentResolver resolver = getContentResolver();        resolver.unregisterContentObserver(mFavoritesObserver);    }

Step 3：Step1中的数据库mFavoritesObserver监听内部类如下：

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1.  /\*\*
2.   \* Receives notifications whenever the user favorites have changed.
3.   \*/
4.  private final ContentObserver mFavoritesObserver =new ContentObserver(new Handler()) \{
5.  @Override
6.  public void onChange(boolean selfChange) \{
7.  mModel.startLoader(LauncherApplication.this,false);
8.  \}
9.  \};

/**     * Receives notifications whenever the user favorites have changed.     */    private final ContentObserver mFavoritesObserver = new ContentObserver(new Handler()) {        @Override        public void onChange(boolean selfChange) {            mModel.startLoader(LauncherApplication.this, false);        }    };

说明：mModel.startLoader（。。，。。）是开启一个线程，设置线程的优先级NORM\_PRIORITY，开始load桌面图标对应的数据库，这个过程是和Launcher.onCreate()同时进行的；

Step 4: 接着我们来看看mModel.startLoader(LauncherApplication.this, false)的方法：

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1.  public void startLoader(Context context,boolean isLaunching) \{
2.  synchronized (mLock) \{
3.  if (DEBUG\_LOADERS) \{
4.  Log.d(TAG, "startLoader isLaunching=" \+ isLaunching);
5.  \}
6.  
7.  // Don't bother to start the thread if we know it's not going to do anything
8.  if (mCallbacks != null && mCallbacks.get() !=null) \{
9.  // If there is already one running, tell it to stop.
10. // also, don't downgrade isLaunching if we're already running
11. isLaunching = isLaunching || stopLoaderLocked();
12. mLoaderTask = new LoaderTask(context, isLaunching);
13. sWorkerThread.setPriority(Thread.NORM\_PRIORITY);
14. sWorker.post(mLoaderTask);
15. \}
16. \}
17. \}

public void startLoader(Context context, boolean isLaunching) {        synchronized (mLock) {            if (DEBUG_LOADERS) {                Log.d(TAG, "startLoader isLaunching=" + isLaunching);            }            // Don't bother to start the thread if we know it's not going to do anything            if (mCallbacks != null && mCallbacks.get() != null) {                // If there is already one running, tell it to stop.                // also, don't downgrade isLaunching if we're already running                isLaunching = isLaunching || stopLoaderLocked();                mLoaderTask = new LoaderTask(context, isLaunching);                sWorkerThread.setPriority(Thread.NORM_PRIORITY);                sWorker.post(mLoaderTask);            }        }    }

Step 5：接着我们来看看LoaderTask.java的run（）方法：

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1.  public void run() \{
2.  // Optimize for end-user experience: if the Launcher is up and // running with the
3.  // All Apps interface in the foreground, load All Apps first. Otherwise, load the
4.  // workspace first (default).
5.  final Callbacks cbk = mCallbacks.get();
6.  final boolean loadWorkspaceFirst = cbk !=null ? (!cbk.isAllAppsVisible()) : true;
7.  
8.  keep\_running: \{
9.  // Elevate priority when Home launches for the first time to avoid
10. // starving at boot time. Staring at a blank home is not cool.
11. synchronized (mLock) \{
12. if (DEBUG\_LOADERS) Log.d(TAG,"Setting thread priority to " \+
13. (mIsLaunching ? "DEFAULT" :"BACKGROUND"));
14. android.os.Process.setThreadPriority(mIsLaunching
15. ? Process.THREAD\_PRIORITY\_DEFAULT : Process.THREAD\_PRIORITY\_BACKGROUND);
16. \}
17. if (loadWorkspaceFirst) \{
18. if (DEBUG\_LOADERS) Log.d(TAG,"step 1: loading workspace");
19. loadAndBindWorkspace();
20. \} else \{
21. if (DEBUG\_LOADERS) Log.d(TAG,"step 1: special: loading all apps");
22. loadAndBindAllApps();
23. \}
24. 
25. if (mStopped) \{
26. break keep\_running;
27. \}
28. 
29. // Whew! Hard work done. Slow us down, and wait until the UI thread has
30. // settled down.
31. synchronized (mLock) \{
32. if (mIsLaunching) \{
33. if (DEBUG\_LOADERS) Log.d(TAG,"Setting thread priority to BACKGROUND");
34. android.os.Process.setThreadPriority(Process.THREAD\_PRIORITY\_BACKGROUND);
35. \}
36. \}
37. waitForIdle();
38. 
39. // second step
40. if (loadWorkspaceFirst) \{
41. if (DEBUG\_LOADERS) Log.d(TAG,"step 2: loading all apps");
42. loadAndBindAllApps();
43. \} else \{
44. if (DEBUG\_LOADERS) Log.d(TAG,"step 2: special: loading workspace");
45. loadAndBindWorkspace();
46. \}
47. 
48. // Restore the default thread priority after we are done loading items
49. synchronized (mLock) \{
50. android.os.Process.setThreadPriority(Process.THREAD\_PRIORITY\_DEFAULT);
51. \}
52. \}
53. 
54. 
55. // Update the saved icons if necessary
56. if (DEBUG\_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons");
57. for (Object key : sDbIconCache.keySet()) \{
58. updateSavedIcon(mContext, (ShortcutInfo) key, sDbIconCache.get(key));
59. \}
60. sDbIconCache.clear();
61. 
62. // Clear out this reference, otherwise we end up holding it until all of the
63. // callback runnables are done.
64. mContext = null;
65. 
66. synchronized (mLock) \{
67. // If we are still the last one to be scheduled, remove ourselves.
68. if (mLoaderTask == this) \{
69. mLoaderTask = null;
70. \}
71. \}
72. \}
73. 
74. public void stopLocked() \{
75. synchronized (LoaderTask.this) \{
76. mStopped = true;
77. this.notify();
78. \}
79. \}

public void run() {            // Optimize for end-user experience: if the Launcher is up and // running with the            // All Apps interface in the foreground, load All Apps first. Otherwise, load the            // workspace first (default).            final Callbacks cbk = mCallbacks.get();            final boolean loadWorkspaceFirst = cbk != null ? (!cbk.isAllAppsVisible()) : true;            keep_running: {                // Elevate priority when Home launches for the first time to avoid                // starving at boot time. Staring at a blank home is not cool.                synchronized (mLock) {                    if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to " +                            (mIsLaunching ? "DEFAULT" : "BACKGROUND"));                    android.os.Process.setThreadPriority(mIsLaunching                            ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);                }                if (loadWorkspaceFirst) {                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");                    loadAndBindWorkspace();                } else {                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: special: loading all apps");                    loadAndBindAllApps();                }                if (mStopped) {                    break keep_running;                }                // Whew! Hard work done.  Slow us down, and wait until the UI thread has                // settled down.                synchronized (mLock) {                    if (mIsLaunching) {                        if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to BACKGROUND");                        android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);                    }                }                waitForIdle();                // second step                if (loadWorkspaceFirst) {                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: loading all apps");                    loadAndBindAllApps();                } else {                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: special: loading workspace");                    loadAndBindWorkspace();                }                // Restore the default thread priority after we are done loading items                synchronized (mLock) {                    android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);                }            }            // Update the saved icons if necessary            if (DEBUG_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons");            for (Object key : sDbIconCache.keySet()) {                updateSavedIcon(mContext, (ShortcutInfo) key, sDbIconCache.get(key));            }            sDbIconCache.clear();            // Clear out this reference, otherwise we end up holding it until all of the            // callback runnables are done.            mContext = null;            synchronized (mLock) {                // If we are still the last one to be scheduled, remove ourselves.                if (mLoaderTask == this) {                    mLoaderTask = null;                }            }        }        public void stopLocked() {            synchronized (LoaderTask.this) {                mStopped = true;                this.notify();            }        }

加载桌面图标对应的数据库的值，这些值能把这些图标显示在屏幕上。

Step 6：LauncherApplication.onCreate()方法启动完成后，接着开始调用Launcher.java的onCreate()方法。代码如下：

**\[java\]** [view plain][] [copy][view plain] [print][view plain] [?][view plain]

1.  @Override
2.  protected void onCreate(Bundle savedInstanceState) \{
3.  super.onCreate(savedInstanceState);
4.  // 得到LauncherApplication的对象app
5.  LauncherApplication app = ((LauncherApplication)getApplication());
6.  // 得到LauncherModel对象mModel,设置一个mCallbacks = new WeakReference<Callbacks>(callbacks)的
7.  // 回调callbacks
8.  mModel = app.setLauncher(this);
9.  // 得到图标缓存的对象mIconCache
10. mIconCache = app.getIconCache();
11. // 得到拖拽控制类DragController的对象
12. mDragController = new DragController(this);
13. // 得到一个LayoutInflater布局的对象
14. mInflater = getLayoutInflater();
15. 
16. // 得到一个AppWidgetManager的对象
17. mAppWidgetManager = AppWidgetManager.getInstance(this);
18. // 得到LauncherAppWidgetHost的一个对象
19. mAppWidgetHost = new LauncherAppWidgetHost(this, APPWIDGET\_HOST\_ID);
20. // Start receiving onAppWidgetChanged calls for your AppWidgets.
21. mAppWidgetHost.startListening();
22. 
23. if (PROFILE\_STARTUP) \{
24. android.os.Debug.startMethodTracing(
25. Environment.getExternalStorageDirectory() +"/launcher");
26. \}
27. 
28. // 检查Locale的语言级别，mcc, mnc的改变
29. checkForLocaleChange();
30. // 加载Launcher.xml布局文件
31. setContentView(R.layout.launcher);
32. // Launcher的布局的初始化
33. setupViews();
34. // 第一次启动Android的展示设置向导,
35. // 这个SharedPreferences中存在
36. // <boolean name="cling.workspace.dismissed" value="true" />
37. // 如果值为true，则不显示设置向导，为false，则显示设置向导。
38. showFirstRunWorkspaceCling();
39. 
40. // 注册数据库观察者
41. registerContentObservers();
42. 
43. lockAllApps();
44. 
45. mSavedState = savedInstanceState;
46. restoreState(mSavedState);
47. 
48. // Update customization drawer \_after\_ restoring the states
49. if (mAppsCustomizeContent !=null) \{
50. mAppsCustomizeContent.onPackagesUpdated();
51. \}
52. 
53. if (PROFILE\_STARTUP) \{
54. android.os.Debug.stopMethodTracing();
55. \}
56. 
57. if (!mRestoring) \{
58. mModel.startLoader(this, true);
59. \}
60. 
61. if (!mModel.isAllAppsLoaded()) \{
62. ViewGroup appsCustomizeContentParent = (ViewGroup) mAppsCustomizeContent.getParent();
63. mInflater.inflate(R.layout.apps\_customize\_progressbar, appsCustomizeContentParent);
64. \}
65. 
66. // For handling default keys
67. mDefaultKeySsb = new SpannableStringBuilder();
68. Selection.setSelection(mDefaultKeySsb, 0);
69. 
70. // 注册系统对话框消失的监听
71. IntentFilter filter = new IntentFilter(Intent.ACTION\_CLOSE\_SYSTEM\_DIALOGS);
72. registerReceiver(mCloseSystemDialogsReceiver, filter);
73. 
74. boolean searchVisible = false;
75. boolean voiceVisible =false;
76. // If we have a saved version of these external icons, we load them up immediately
77. // 如果我们已经保存了外部图标的版本，我们立即加载它们
78. int coi = getCurrentOrientationIndexForGlobalIcons();
79. if (sGlobalSearchIcon\[coi\] ==null || sVoiceSearchIcon\[coi\] == null ||
80. sAppMarketIcon\[coi\] == null) \{
81. updateAppMarketIcon();
82. searchVisible = updateGlobalSearchIcon();
83. voiceVisible = updateVoiceSearchIcon(searchVisible);
84. \}
85. if (sGlobalSearchIcon\[coi\] !=null) \{
86. updateGlobalSearchIcon(sGlobalSearchIcon\[coi\]);
87. searchVisible = true;
88. \}
89. if (sVoiceSearchIcon\[coi\] !=null) \{
90. updateVoiceSearchIcon(sVoiceSearchIcon\[coi\]);
91. voiceVisible = true;
92. \}
93. if (sAppMarketIcon\[coi\] !=null) \{
94. updateAppMarketIcon(sAppMarketIcon\[coi\]);
95. \}
96. mSearchDropTargetBar.onSearchPackagesChanged(searchVisible, voiceVisible);
97. 
98. // On large interfaces, we want the screen to auto-rotate based on the current orientation
99. if (LauncherApplication.isScreenLarge() || Build.TYPE.contentEquals("eng")) \{
100. setRequestedOrientation(ActivityInfo.SCREEN\_ORIENTATION\_UNSPECIFIED);
101. \}
102. \}

@Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        // 得到LauncherApplication的对象app        LauncherApplication app = ((LauncherApplication)getApplication());        // 得到LauncherModel对象mModel,设置一个mCallbacks = new WeakReference<Callbacks>(callbacks)的        // 回调callbacks        mModel = app.setLauncher(this);        // 得到图标缓存的对象mIconCache        mIconCache = app.getIconCache();        // 得到拖拽控制类DragController的对象        mDragController = new DragController(this);        // 得到一个LayoutInflater布局的对象        mInflater = getLayoutInflater();        // 得到一个AppWidgetManager的对象        mAppWidgetManager = AppWidgetManager.getInstance(this);        // 得到LauncherAppWidgetHost的一个对象        mAppWidgetHost = new LauncherAppWidgetHost(this, APPWIDGET_HOST_ID);        // Start receiving onAppWidgetChanged calls for your AppWidgets.        mAppWidgetHost.startListening();        if (PROFILE_STARTUP) {            android.os.Debug.startMethodTracing(                    Environment.getExternalStorageDirectory() + "/launcher");        }        // 检查Locale的语言级别，mcc, mnc的改变        checkForLocaleChange();        // 加载Launcher.xml布局文件        setContentView(R.layout.launcher);        // Launcher的布局的初始化        setupViews();        // 第一次启动Android的展示设置向导,        // 这个SharedPreferences中存在        // <boolean name="cling.workspace.dismissed" value="true" />        // 如果值为true，则不显示设置向导，为false，则显示设置向导。        showFirstRunWorkspaceCling();        // 注册数据库观察者        registerContentObservers();        lockAllApps();        mSavedState = savedInstanceState;        restoreState(mSavedState);        // Update customization drawer _after_ restoring the states        if (mAppsCustomizeContent != null) {            mAppsCustomizeContent.onPackagesUpdated();        }        if (PROFILE_STARTUP) {            android.os.Debug.stopMethodTracing();        }        if (!mRestoring) {            mModel.startLoader(this, true);        }        if (!mModel.isAllAppsLoaded()) {            ViewGroup appsCustomizeContentParent = (ViewGroup) mAppsCustomizeContent.getParent();            mInflater.inflate(R.layout.apps_customize_progressbar, appsCustomizeContentParent);        }        // For handling default keys        mDefaultKeySsb = new SpannableStringBuilder();        Selection.setSelection(mDefaultKeySsb, 0);        // 注册系统对话框消失的监听        IntentFilter filter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);        registerReceiver(mCloseSystemDialogsReceiver, filter);        boolean searchVisible = false;        boolean voiceVisible = false;        // If we have a saved version of these external icons, we load them up immediately        // 如果我们已经保存了外部图标的版本，我们立即加载它们        int coi = getCurrentOrientationIndexForGlobalIcons();        if (sGlobalSearchIcon[coi] == null || sVoiceSearchIcon[coi] == null ||                sAppMarketIcon[coi] == null) {            updateAppMarketIcon();            searchVisible = updateGlobalSearchIcon();            voiceVisible = updateVoiceSearchIcon(searchVisible);        }        if (sGlobalSearchIcon[coi] != null) {             updateGlobalSearchIcon(sGlobalSearchIcon[coi]);             searchVisible = true;        }        if (sVoiceSearchIcon[coi] != null) {            updateVoiceSearchIcon(sVoiceSearchIcon[coi]);            voiceVisible = true;        }        if (sAppMarketIcon[coi] != null) {            updateAppMarketIcon(sAppMarketIcon[coi]);        }        mSearchDropTargetBar.onSearchPackagesChanged(searchVisible, voiceVisible);        // On large interfaces, we want the screen to auto-rotate based on the current orientation        if (LauncherApplication.isScreenLarge() || Build.TYPE.contentEquals("eng")) {            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);        }    }

Step 7：其中LauncherModel这个类中有个回调接口，具体定义如下：

**\[java\]** [view plain][] [copy][view plain] [print][view plain] [?][view plain]

1.  public interface Callbacks \{
2.  public boolean setLoadOnResume();
3.  public int getCurrentWorkspaceScreen();
4.  public void startBinding();
5.  public void bindItems(ArrayList<ItemInfo> shortcuts,int start, int end);
6.  public void bindFolders(HashMap<Long,FolderInfo> folders);
7.  public void finishBindingItems();
8.  public void bindAppWidget(LauncherAppWidgetInfo info);
9.  public void bindAllApplications(ArrayList<ApplicationInfo> apps);
10. public void bindAppsAdded(ArrayList<ApplicationInfo> apps);
11. public void bindAppsUpdated(ArrayList<ApplicationInfo> apps);
12. public void bindAppsRemoved(ArrayList<ApplicationInfo> apps,boolean permanent);
13. public void bindPackagesUpdated();
14. public boolean isAllAppsVisible();
15. public void bindSearchablesChanged();
16. \}

public interface Callbacks {        public boolean setLoadOnResume();        public int getCurrentWorkspaceScreen();        public void startBinding();        public void bindItems(ArrayList<ItemInfo> shortcuts, int start, int end);        public void bindFolders(HashMap<Long,FolderInfo> folders);        public void finishBindingItems();        public void bindAppWidget(LauncherAppWidgetInfo info);        public void bindAllApplications(ArrayList<ApplicationInfo> apps);        public void bindAppsAdded(ArrayList<ApplicationInfo> apps);        public void bindAppsUpdated(ArrayList<ApplicationInfo> apps);        public void bindAppsRemoved(ArrayList<ApplicationInfo> apps, boolean permanent);        public void bindPackagesUpdated();        public boolean isAllAppsVisible();        public void bindSearchablesChanged();    }

对LauncherModel进行初始化的时候 mModel = app.setLauncher(this);---->mModel.initialize(launcher);----->

public void initialize(Callbacks callbacks) \{  
synchronized (mLock) \{  
mCallbacks = new WeakReference<Callbacks>(callbacks);  
\}  
\}

这个callbacks就是定义的接口回调，具体实现是在Launcher.java中定义的，启动Launcher的过程中，这些实现是异步来实现的。还有Launcher.java的onResume（）方法没有讲解，到这儿基本上Android的Launcher已经启动起来了，这个onResume（）我研究后再更新。

AndroidICS4.0版本的launcher拖拽的流程，基本和2.3的相似。就是比2.3写的封装的接口多了一些，比如删除类的写法就多了个类。等等。4.0的改变有一些，但是不是特别大。这个月一直在改动Launcher的缩略图的效果，4.0的缩略图的功能没有实现，还得从2.3的Launcher中摘出来。通过做这个缩略图对Launcher的模块有一点点了解，拿来分享一下Launcher拖拽的工作流程。![微笑][smile.gif]**有图有真相！![吐舌头][tongue.gif]**

**转载请标明出处：[http://blog.csdn.net/wdaming1986/article/details/7671318][http_blog.csdn.net_wdaming1986_article_details_7671318]**

**（1）****先来看看类之间的继承关系**

![1339929258_8122.PNG][]

**图（1）**

**（2）再来看看Launcher拖拽流程的时序图**

![1339929475_3267.PNG][]

**图（2）**

**下面咱们分步来解析Launcher拖拽的详细过程：**

**step 1 ：先来看看Launcher.java这个类的onCreate（）方法中的setupViews（）方法中的一部分代码：**

**\[java\]** [view plain][view plain 1] [copy][view plain 1] [print][view plain 1] [?][view plain 1]

1.  <strong> </strong><span style="color: rgb(0, 0, 0); font-size: 16px;">// Setup the workspace
2.  mWorkspace.setHapticFeedbackEnabled(false);
3.  mWorkspace.setOnLongClickListener(this);
4.  mWorkspace.setup(dragController);
5.  dragController.addDragListener(mWorkspace);</span>

// Setup the workspace        mWorkspace.setHapticFeedbackEnabled(false);        mWorkspace.setOnLongClickListener(this);        mWorkspace.setup(dragController);        dragController.addDragListener(mWorkspace);

**Workspace设置长按事件的监听交给了Launcher.java这个类了。所以在主屏上长按事件会走到Launcher.java----->**

**onLongClick()这个方法中去；**

**step 2 ：接着我们来看看Launcher.java中onLongClick()的代码：**

**\[java\]** [view plain][view plain 1] [copy][view plain 1] [print][view plain 1] [?][view plain 1]

1.  public boolean onLongClick(View v) \{
2.  ··············
3.  // The hotseat touch handling does not go through Workspace, and we always allow long press
4.  // on hotseat items.
5.  final View itemUnderLongClick = longClickCellInfo.cell;
6.  boolean allowLongPress = isHotseatLayout(v) || mWorkspace.allowLongPress();
7.  if (allowLongPress && !mDragController.isDragging()) \{
8.  if (itemUnderLongClick ==null) \{
9.  // User long pressed on empty space
10. mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG\_PRESS,
11. HapticFeedbackConstants.FLAG\_IGNORE\_VIEW\_SETTING);
12. startWallpaper();
13. \} else \{
14. if (!(itemUnderLongClickinstanceof Folder)) \{
15. // User long pressed on an item
16. mWorkspace.startDrag(longClickCellInfo);
17. \}
18. \}
19. \}
20. return true;
21. \}

public boolean onLongClick(View v) {         ·············· // The hotseat touch handling does not go through Workspace, and we always allow long press        // on hotseat items.        final View itemUnderLongClick = longClickCellInfo.cell;        boolean allowLongPress = isHotseatLayout(v) || mWorkspace.allowLongPress();        if (allowLongPress && !mDragController.isDragging()) {            if (itemUnderLongClick == null) {                // User long pressed on empty space                mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS,                        HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING);                startWallpaper();            } else {                if (!(itemUnderLongClick instanceof Folder)) {                    // User long pressed on an item                    mWorkspace.startDrag(longClickCellInfo);                }            }        }        return true;    }

通过itemUnderLongClick == null 来判断，在屏幕上触发长按事件是否选中了shortcut或者widget。如果为空，就启动桌面的壁纸，else，就把拖拽事件往Workspace.java这个类传递。

Step 3 ：通过mWorkspace.startDrag(longClickCellInfo)，把长按事件传递给workspace来处理，具体来看代码：

**\[java\]** [view plain][view plain 1] [copy][view plain 1] [print][view plain 1] [?][view plain 1]

1.  void startDrag(CellLayout.CellInfo cellInfo) \{
2.  View child = cellInfo.cell;
3.  
4.  // Make sure the drag was started by a long press as opposed to a long click.
5.  if (!child.isInTouchMode()) \{
6.  return;
7.  \}
8.  
9.  mDragInfo = cellInfo;
10. //隐藏拖拽的child
11. child.setVisibility(GONE);
12. 
13. child.clearFocus();
14. child.setPressed(false);
15. 
16. final Canvas canvas = new Canvas();
17. 
18. // We need to add extra padding to the bitmap to make room for the glow effect
19. final int bitmapPadding = HolographicOutlineHelper.MAX\_OUTER\_BLUR\_RADIUS;
20. 
21. // The outline is used to visualize where the item will land if dropped
22. mDragOutline = createDragOutline(child, canvas, bitmapPadding);
23. beginDragShared(child, this);
24. \}

void startDrag(CellLayout.CellInfo cellInfo) {        View child = cellInfo.cell;        // Make sure the drag was started by a long press as opposed to a long click.        if (!child.isInTouchMode()) {            return;        }        mDragInfo = cellInfo;        //隐藏拖拽的child        child.setVisibility(GONE);        child.clearFocus();        child.setPressed(false);        final Canvas canvas = new Canvas();        // We need to add extra padding to the bitmap to make room for the glow effect        final int bitmapPadding = HolographicOutlineHelper.MAX_OUTER_BLUR_RADIUS;        // The outline is used to visualize where the item will land if dropped        mDragOutline = createDragOutline(child, canvas, bitmapPadding);        beginDragShared(child, this);    }

上面的代码主要做的工作是：把正在拖拽的这个view隐藏掉，在主屏幕上绘制一个蓝色的，大小和图标相似的一个边框，以表示能在主屏的这个位置放置。

Step 4 ：接着调用beginDragShared(child, this)这个方法，代码如下：

**\[java\]** [view plain][view plain 1] [copy][view plain 1] [print][view plain 1] [?][view plain 1]

1.  public void beginDragShared(View child, DragSource source) \{
2.  ··· ···
3.  // Clear the pressed state if necessary
4.  if (child instanceof BubbleTextView) \{
5.  BubbleTextView icon = (BubbleTextView) child;
6.  icon.clearPressedOrFocusedBackground();
7.  \}
8.  
9.  mDragController.startDrag(b, dragLayerX, dragLayerY, source, child.getTag(),
10. DragController.DRAG\_ACTION\_MOVE, dragVisualizeOffset, dragRect);
11. b.recycle();
12. \}

public void beginDragShared(View child, DragSource source) {    ··· ···// Clear the pressed state if necessary        if (child instanceof BubbleTextView) {            BubbleTextView icon = (BubbleTextView) child;            icon.clearPressedOrFocusedBackground();        }        mDragController.startDrag(b, dragLayerX, dragLayerY, source, child.getTag(),                DragController.DRAG_ACTION_MOVE, dragVisualizeOffset, dragRect);        b.recycle();    }

这个方法做的工作是：开始进行拖拽，绘制正在拖拽的图片，把拖拽的事件交给DragController来处理。

Step 5 ：接着来看看mDragController.startDrag(b, dragLayerX, dragLayerY, source, child.getTag(), DragController.DRAG\_ACTION\_MOVE, dragVisualizeOffset, dragRect)这个方法，代码如下：

**\[java\]** [view plain][view plain 1] [copy][view plain 1] [print][view plain 1] [?][view plain 1]

1.  public void startDrag(Bitmap b, int dragLayerX,int dragLayerY,
2.  DragSource source, Object dragInfo, int dragAction, Point dragOffset, Rect dragRegion) \{
3.  ··· ···
4.  mDragObject.dragComplete = false;
5.  mDragObject.xOffset = mMotionDownX - (dragLayerX + dragRegionLeft);
6.  mDragObject.yOffset = mMotionDownY - (dragLayerY + dragRegionTop);
7.  mDragObject.dragSource = source;
8.  mDragObject.dragInfo = dragInfo;
9.  mVibrator.vibrate(VIBRATE\_DURATION);
10. 
11. final DragView dragView = mDragObject.dragView =new DragView(mLauncher, b, registrationX,
12. registrationY, 0, 0, b.getWidth(), b.getHeight());
13. 
14. if (dragOffset != null) \{
15. dragView.setDragVisualizeOffset(new Point(dragOffset));
16. \}
17. if (dragRegion !=null) \{
18. dragView.setDragRegion(new Rect(dragRegion));
19. \}
20. 
21. dragView.show(mMotionDownX, mMotionDownY);
22. handleMoveEvent(mMotionDownX, mMotionDownY);
23. \}

public void startDrag(Bitmap b, int dragLayerX, int dragLayerY,            DragSource source, Object dragInfo, int dragAction, Point dragOffset, Rect dragRegion) {··· ··· mDragObject.dragComplete = false;        mDragObject.xOffset = mMotionDownX - (dragLayerX + dragRegionLeft);        mDragObject.yOffset = mMotionDownY - (dragLayerY + dragRegionTop);        mDragObject.dragSource = source;        mDragObject.dragInfo = dragInfo;mVibrator.vibrate(VIBRATE_DURATION);        final DragView dragView = mDragObject.dragView = new DragView(mLauncher, b, registrationX,                registrationY, 0, 0, b.getWidth(), b.getHeight());        if (dragOffset != null) {            dragView.setDragVisualizeOffset(new Point(dragOffset));        }        if (dragRegion != null) {            dragView.setDragRegion(new Rect(dragRegion));        }        dragView.show(mMotionDownX, mMotionDownY);        handleMoveEvent(mMotionDownX, mMotionDownY);    }

这个方法的作用是：计算要拖拽的view的大小，显示在workspace上，dragView.show(mMotionDownX, mMotionDownY);这个show（）会根据手指的移动而移动的。然后在通过handleMoveEvent（）方法来分发拖拽的目标到底在哪个目标上。DropTarget一共有3个：workspace，ButtonDropTarget（删除类），Folder；他们分别实现了DropTarget这个接口。

下面来看看这个接口有一下几个方法：

**\[java\]** [view plain][view plain 1] [copy][view plain 1] [print][view plain 1] [?][view plain 1]

1.  boolean isDropEnabled();
2.  void onDrop(DragObject dragObject);
3.  
4.  void onDragEnter(DragObject dragObject);
5.  
6.  void onDragOver(DragObject dragObject);
7.  
8.  void onDragExit(DragObject dragObject);
9.  DropTarget getDropTargetDelegate(DragObject dragObject);
10. boolean acceptDrop(DragObject dragObject);
11. 
12. // These methods are implemented in Views
13. void getHitRect(Rect outRect);
14. void getLocationInDragLayer(int\[\] loc);
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