Android Launcher 详解

扶醉桌前 提交于 2020-01-22 08:17:24

(1)      Launcher的定义:Android系统启动后,加载的第一个程序,是其他应用程序的入口。

(2)      Launcher的构成:HomeScreen(1.workspace(AppWidget,Wallpaper,Livefolder,ShortCut),2.HotSeats,3.AllApps/allApplist:GridView)


(3)      针对Launcher的开发类型:

    1.      开发自定义的Launcher

2.      与Workspace相关的开发(AppWidget,Wallpaper,Livefolder,ShortCut)

(4)      解读Launcher源代码(以ShortCut为例),Launcher为系统级应用,位于Applications层。源代码位于MyAndroid\packages\apps\Launcher2中,可讲它导入eclipse中。

(5)      看Manifest文件可知,Launcher的主Activity为:com.android.launcher2.Launcher。下面是它的部分配置信息:

<activity
android:name="com.android.launcher2.Launcher"
android:launchMode="singleTask">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.MONKEY"/>
</intent-filter>
</activity>

(6)      关于Activity的四种加载模式(android:launchMode):在多Activity开发中,有可能是自己应用之间的Activity跳转,或者夹带其他应用的可复用Activity。有可能会希望跳转到原来某个Activity实例,而不是产生大量重复的Activity。这就需要为Activity配置特定的加载模式,而不是默认的加载模式。

1.      Standard:默认模式,每次激活Activity时都会创建Activity,并放入任务栈中。

2.      singleTop:如果在任务栈栈顶正好存在该Activity的实例,就重用该实例(会调用实例的onNewIntent()),否则就会创建新的实例并放入栈顶,即使栈中已经存在该Activity的实例。

3.      singleTask:如果在栈中已经有该Activity的实例,就会重用该实例,重用时,会让该实例回到栈顶,因此在它上面的实例将会被移出栈。

4.      singleInstance:在一个新栈中创建该Activity的实例,并让多个应用共享该栈中的该Activity实例。一旦该模式的Activity实例已经存在于某个栈中,任何应用再激活该Activity时都会重用该栈中的实例( 会调用实例的onNewIntent() )。其效果相当于多个应用共享一个应用,不管谁激活该 Activity 都会进入同一个应用中。


(7)      当用户按菜单键中的添加按钮或者长按workspace中的空白区域,会弹出一个对话框(如下图所示):





@Override
publicbooleanonOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
caseMENU_ADD:
addItems(); /* 按菜单键,添加按钮*/
returntrue;
caseMENU_MANAGE_APPS:
manageApps();
returntrue;
caseMENU_WALLPAPER_SETTINGS:
startWallpaper();
returntrue;
caseMENU_SEARCH:

@Override
publicbooleanonOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
caseMENU_ADD:
addItems(); /* 按菜单键,添加按钮*/
returntrue;
caseMENU_MANAGE_APPS:
manageApps();
returntrue;
caseMENU_WALLPAPER_SETTINGS:
startWallpaper();
returntrue;
caseMENU_SEARCH:
onSearchRequested();
returntrue;
caseMENU_NOTIFICATIONS:
showNotifications();
returntrue;
        }

returnsuper.onOptionsItemSelected(item);
    }

privatevoidaddItems() {
closeAllApps(true);
showAddDialog(mMenuAddInfo); /* 显示对话框 */
}

// 长按workspace空白区域
if (mWorkspace.allowLongPress()) {
if (cellInfo.cell == null) {
if (cellInfo.valid) {
// User long pressed on empty space
mWorkspace.setAllowLongPress(false);
mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS,
HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING);
showAddDialog(cellInfo);/* 显示对话框 */
                }
            } else {
if (!(cellInfo.cellinstanceof Folder)) {
// User long pressed on an item
mWorkspace.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS,
HapticFeedbackConstants.FLAG_IGNORE_VIEW_SETTING);
mWorkspace.startDrag(cellInfo);
                }
            }
        }
// showAddDialog方法
privatevoidshowAddDialog(CellLayout.CellInfocellInfo) {
mAddItemCellInfo = cellInfo;
mWaitingForResult = true;
showDialog(DIALOG_CREATE_SHORTCUT);
    }

// showDialog方法会调用下面这个方法创建对话框
protected Dialog onCreateDialog(int id) {
switch (id) {
caseDIALOG_CREATE_SHORTCUT: // 注意这里的常量
returnnewCreateShortcut().createDialog();
caseDIALOG_RENAME_FOLDER:
returnnewRenameFolder().createDialog();
        }

returnsuper.onCreateDialog(id);
    }

// CreateShortcut为Launcher的内部类,看其中的pickShortcut()
// 方法,它实现很多接口

/**
     * Displays the shortcut creation dialog and launches, if necessary, theappropriate activity.
     */
privateclassCreateShortcutimplementsDialogInterface.OnClickListener,
DialogInterface.OnCancelListener, DialogInterface.OnDismissListener,
DialogInterface.OnShowListener {

privateAddAdaptermAdapter;

        Dialog createDialog() {
mAdapter = newAddAdapter(Launcher.this);

finalAlertDialog.Builder builder = newAlertDialog.Builder(Launcher.this);
builder.setTitle(getString(R.string.menu_item_add_item));
builder.setAdapter(mAdapter, this);

builder.setInverseBackgroundForced(true);

AlertDialog dialog = builder.create();
dialog.setOnCancelListener(this);
dialog.setOnDismissListener(this);
dialog.setOnShowListener(this);

return dialog;
        }

publicvoidonCancel(DialogInterface dialog) {
mWaitingForResult = false;
            cleanup();
        }

publicvoidonDismiss(DialogInterface dialog) {
        }

privatevoid cleanup() {
try {
dismissDialog(DIALOG_CREATE_SHORTCUT);
            } catch (Exception e) {
// An exception is thrown if the dialog is not visible, which is fine
            }
        }

/**
         * Handle the action clicked in the “Add to home” dialog.
         */
publicvoidonClick(DialogInterface dialog, int which) {
            Resources res = getResources();
            cleanup();

switch (which) {
caseAddAdapter.ITEM_SHORTCUT: {
// Insert extra item to handle picking application
pickShortcut(); //当点击对话框中的快捷方式项,会//调用此方法
break;
                }

caseAddAdapter.ITEM_APPWIDGET: {
intappWidgetId = Launcher.this.mAppWidgetHost.allocateAppWidgetId();

                    Intent pickIntent = new Intent(AppWidgetManager.ACTION_APPWIDGET_PICK);
pickIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId);
// start the pick activity
startActivityForResult(pickIntent, REQUEST_PICK_APPWIDGET);
break;
                }

caseAddAdapter.ITEM_LIVE_FOLDER: {
// Insert extra item to handle inserting folder
                    Bundle bundle = new Bundle();

ArrayList<String>shortcutNames = newArrayList<String>();
shortcutNames.add(res.getString(R.string.group_folder));
bundle.putStringArrayList(Intent.EXTRA_SHORTCUT_NAME, shortcutNames);

ArrayList<ShortcutIconResource>shortcutIcons =
newArrayList<ShortcutIconResource>();
                    shortcutIcons.add(ShortcutIconResource.fromContext(Launcher.this,
R.drawable.ic_launcher_folder));
                    bundle.putParcelableArrayList(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, shortcutIcons);

                    Intent pickIntent = new Intent(Intent.ACTION_PICK_ACTIVITY);
pickIntent.putExtra(Intent.EXTRA_INTENT,
new Intent(LiveFolders.ACTION_CREATE_LIVE_FOLDER));
pickIntent.putExtra(Intent.EXTRA_TITLE,
getText(R.string.title_select_live_folder));
pickIntent.putExtras(bundle);

startActivityForResult(pickIntent, REQUEST_PICK_LIVE_FOLDER);
break;
                }

caseAddAdapter.ITEM_WALLPAPER: {
startWallpaper();
break;
                }
            }
        }

publicvoidonShow(DialogInterface dialog) {
mWaitingForResult = true;            
        }
    }


// pickShortcut()方法
privatevoidpickShortcut() {
        Bundle bundle = new Bundle();

ArrayList<String>shortcutNames = newArrayList<String>();
shortcutNames.add(getString(R.string.group_applications));
bundle.putStringArrayList(Intent.EXTRA_SHORTCUT_NAME, shortcutNames);

ArrayList<ShortcutIconResource>shortcutIcons = newArrayList<ShortcutIconResource>();
        shortcutIcons.add(ShortcutIconResource.fromContext(Launcher.this,
R.drawable.ic_launcher_application));
        bundle.putParcelableArrayList(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, shortcutIcons);

        Intent pickIntent = new Intent(Intent.ACTION_PICK_ACTIVITY);
pickIntent.putExtra(Intent.EXTRA_INTENT, new Intent(Intent.ACTION_CREATE_SHORTCUT));
pickIntent.putExtra(Intent.EXTRA_TITLE, getText(R.string.title_select_shortcut));
pickIntent.putExtras(bundle);

startActivityForResult(pickIntent,REQUEST_PICK_SHORTCUT); // 启动了一个Activity,其实是一个快捷方式//列表,一个回调方法
    }


// 在onActivityResult()中

caseREQUEST_PICK_SHORTCUT:
processShortcut(data); // 回调此方法,data为Intent
break;

voidprocessShortcut(Intent intent) {
// Handle case where user selected "Applications"
        String applicationName = getResources().getString(R.string.group_applications);
        String shortcutName = intent.getStringExtra(Intent.EXTRA_SHORTCUT_NAME);

if (applicationName != null&&applicationName.equals(shortcutName)) {
            Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

            Intent pickIntent = new Intent(Intent.ACTION_PICK_ACTIVITY);
pickIntent.putExtra(Intent.EXTRA_INTENT, mainIntent);
pickIntent.putExtra(Intent.EXTRA_TITLE, getText(R.string.title_select_application));
startActivityForResultSafely(pickIntent, REQUEST_PICK_APPLICATION);
        } else {
startActivityForResultSafely(intent, REQUEST_CREATE_SHORTCUT); //这里还要启动一个Activity
        }
    }


caseREQUEST_CREATE_SHORTCUT:
completeAddShortcut(data, mAddItemCellInfo);
break;


/**
     * Add a shortcut to the workspace.
     *
     * @param data The intent describing the shortcut.
     * @paramcellInfo The position on screen where to create the shortcut.
     */
privatevoidcompleteAddShortcut(Intent data, CellLayout.CellInfocellInfo) {
cellInfo.screen = mWorkspace.getCurrentScreen();
if (!findSingleSlot(cellInfo)) return;

finalShortcutInfo info = mModel.addShortcut(this, data, cellInfo, false);

if (!mRestoring) {
final View view = createShortcut(info);
mWorkspace.addInCurrentScreen(view, cellInfo.cellX, cellInfo.cellY, 1, 1,
isWorkspaceLocked());
        }
    }

(8)      如何让你的应用支持创建Shortcut,即你的应用能够出现在快捷方式列表中。

//  单独创建一个Activity,例如ShortCut.java
//  配置此Activity
<activity 
android:name=".ShortCut">
<intent-filter>
<actionandroid:name="android.intent.action.CREATE_SHORTCUT"/>
</intent-filter>
</activity>
// 以下是它的代码,这个startActivityForResultSafely(intent, //REQUEST_CREATE_SHORTCUT)方法会跳到这个Activity
publicclassShortCutextends Activity {

	@Override
	protectedvoidonCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		if(getIntent().getAction().equals(Intent.ACTION_CREATE_SHORTCUT)) {
			Intent returnIntent = new Intent();
			returnIntent.putExtra(Intent.EXTRA_SHORTCUT_NAME, "应用管理器");
			returnIntent.putExtra(Intent.EXTRA_SHORTCUT_INTENT, new Intent(this, ShowAppActivity.class));
			/* returnIntent.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, 
			Intent.ShortcutIconResource.fromContext(this, R.drawable.icon)); */
			returnIntent.putExtra(Intent.EXTRA_SHORTCUT_ICON, R.drawable.icon);
			setResult(RESULT_OK, returnIntent);
			finish();
		}
	}

}


(9)      如何在用户第一次启动应用后,提示用户是否要创建Shortcut:现在Manifest文件中添加一个权限(<permission android:name="com.android.launcher.permission.INSTALL_SHORTCUT"></permission>)只要向Launcher发送一个广播,数据为一个Intent。此Intent与上面代码中的returnIntent类似,只要这个Intent添加一个Action(

intent.setAction("com.android.launcher.action.INSTALL_SHORTCUT"))。然后sendBroadcast(intent)。在Launcher中有个InstallShortcutReceiver.java,接受这个广播。





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