Launcher是系統啓動後第一個啓動的程序,是其它應用程序的入口,也就是我們的手機程序的桌面程序;
一、Launcher的定義及構成:
<1>通過查看官方提供的Launcher源碼可以知道其實Launcher也是一個Activity,不過它的intent-fliter有點特殊;
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<activity
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Android:name="Launcher"
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android:launchMode="singleTask"
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android:clearTaskOnLaunch="true"
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android:stateNotNeeded="true"
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android:theme="@android:style/Theme.Wallpaper.NoTitleBar"
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android:screenOrientation="nosensor"
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android:windowSoftInputMode="stateUnspecified|adjustPan">
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<intent-filter>
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<action android:name="android.intent.action.MAIN" />
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<category android:name="android.intent.category.HOME"/>
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<category android:name="android.intent.category.DEFAULT" />
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<category android:name="android.intent.category.MONKEY" />
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</intent-filter>
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</activity>
Launcher的intent-filter中,action爲intent.action.MAIN,表示該Activity是程序的主入口,但是它的category是category.HOME,和一般的app不一樣,category.HOME則標識了這個Activity是一個Launcher,其實就是對應的按下HOME鍵所跳轉到的Activity,也就是我們的桌面;
下面我們再來看一下一個普通的App的程序主入口Activity的配置:
<action android:name="android.intent.action.MAIN" /> 表示該類是程序主入口;
<category android:name="android.intent.category.LAUNCHER" />
category.LAUNCHER表示該Activity在Launcher上可見,所以這一個Activity會被添加到Launcher;
<2>Launcher構成:
HomeScreen(WorkSpace+HotSeats), Shortcut(快捷方式), LiveFolder(文件夾), AppWidget(窗口小部件), WallPaper(壁紙); AllAppList:
下面我們就來分別研究探討這四個元素
1、Shortcut
在Launcher的配置文件裏面有這樣一個廣播接收者用於監聽添加快捷方式,查看InstallShortcutReceiver的源碼:
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public class InstallShortcutReceiver extends BroadcastReceiver {
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private static final String ACTION_INSTALL_SHORTCUT =
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"com.android.launcher.action.INSTALL_SHORTCUT";
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private final int[] mCoordinates = new int[2];
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public void onReceive(Context context, Intent data) {
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if (!ACTION_INSTALL_SHORTCUT.equals(data.getAction())) {
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return;
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}
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int screen = Launcher.getScreen();
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if (!installShortcut(context, data, screen)) {
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// The target screen is full, let's try the other screens
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for (int i = 0; i < Launcher.SCREEN_COUNT; i++) {
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if (i != screen && installShortcut(context, data, i)) break;
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}
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}
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}
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}
從上面的核心代碼可以看出,在BroadcastReceiver接收到INSTALL_SHORTCUT廣播之後,會嘗試在當前屏添加快捷方式,如果當前屏滿了,則會嘗試將快捷方式添加到其它屏;因此,當我們想主動添加一個快捷方式到屏幕的時候,其實就很簡單了,發送一個廣播,並且設置它的Action爲INSTALL_SHORTCUT即可;但是,需要注意的是如果僅僅設置Action是不夠的,因爲僅僅這樣做會重複添加快捷方式,如果想不重複添加,還得做一些設置,詳情參考這裏 http://www.linuxidc.com/Linux/2015-03/114623.htm
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2、LiveFolder
在Launcher.Java文件中,找到添加LiveFolder的入口
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Bundle bundle = new Bundle();
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ArrayList<String> shortcutNames = new ArrayList<String>();
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shortcutNames.add(res.getString(R.string.group_folder));
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bundle.putStringArrayList(Intent.EXTRA_SHORTCUT_NAME, shortcutNames);
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ArrayList<ShortcutIconResource> shortcutIcons = new ArrayList<ShortcutIconResource>();
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shortcutIcons.add(ShortcutIconResource.fromContext(Launcher.this, R.drawable.ic_launcher_folder));
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bundle.putParcelableArrayList(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, shortcutIcons);
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Intent pickIntent = new Intent(Intent.ACTION_PICK_ACTIVITY);
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pickIntent.putExtra(Intent.EXTRA_INTENT, new Intent(LiveFolders.ACTION_CREATE_LIVE_FOLDER));
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pickIntent.putExtra(Intent.EXTRA_TITLE, getText(R.string.title_select_live_folder));
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pickIntent.putExtras(bundle);
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startActivityForResult(pickIntent, REQUEST_PICK_LIVE_FOLDER);
當我們長按桌面之後,選擇添加文件夾,則會執行上面這段代碼,在這裏會先創建好一個空文件夾;
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void addLiveFolder(Intent intent) {
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String folderName = getResources().getString(R.string.group_folder);
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String shortcutName = intent.getStringExtra(Intent.EXTRA_SHORTCUT_NAME);
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if (folderName != null && folderName.equals(shortcutName)) {
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addFolder(!mDesktopLocked);
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} else {
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startActivityForResult(intent, REQUEST_CREATE_LIVE_FOLDER);
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}
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}
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完成添加
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private void completeAddLiveFolder(Intent data, CellLayout.CellInfo cellInfo,
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boolean insertAtFirst) {
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cellInfo.screen = mWorkspace.getCurrentScreen();
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if (!findSingleSlot(cellInfo)) return;
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final LiveFolderInfo info = addLiveFolder(this, data, cellInfo, false);
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if (!mRestoring) {
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sModel.addDesktopItem(info);
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final View view = LiveFolderIcon.fromXml(R.layout.live_folder_icon, this,
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(ViewGroup) mWorkspace.getChildAt(mWorkspace.getCurrentScreen()), info);
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mWorkspace.addInCurrentScreen(view, cellInfo.cellX, cellInfo.cellY, 1, 1, insertAtFirst);
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} else if (sModel.isDesktopLoaded()) {
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sModel.addDesktopItem(info);
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}
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}
3、AppWidget:AppWidgetProvider用來在HOME頁面顯示插件
實現步驟:
- 爲AppWidget提供一個元佈局文件AppWigdetProvider_Provider.xml,用來顯示Widget的界面。
- 創建一個類繼承自AppWidgetProvider,並覆寫裏面的相關的方法並且註冊到配置文件。
- 爲WidgetProvider創建一個引用的佈局文件。
>>1、在res/xml/文件夾下創建AppWigdetProvider_Provider.xml文件
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<?xml version="1.0" encoding="utf-8"?>
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<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
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android:initialLayout="@layout/main"
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android:minHeight="50dip"
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android:minWidth="50dip"
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android:updatePeriodMillis="5000" >
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</appwidget-provider>
>>2、修改MainActivity繼承自AppWidgetProvider並覆寫裏面的一些方法,實際上AppWidgetProvider就是一個BroadcastReceiver;
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public class MainActivity extends AppWidgetProvider {
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@Override
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public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
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super.onUpdate(context, appWidgetManager, appWidgetIds);
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Timer timer = new Timer();
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timer.scheduleAtFixedRate(new LYTimeTask(context, appWidgetManager), 1, 50000);
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}
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private class LYTimeTask extends TimerTask {
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RemoteViews remoteViews;
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AppWidgetManager appWidgetManager;
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ComponentName widget;
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@Override
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public void run() {
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Date date = new Date();
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Calendar calendar = new GregorianCalendar(2013, 07, 24);
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long days = (calendar.getTimeInMillis() - date.getTime()) / 1000 / 86400;
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remoteViews.setTextViewText(R.id.worldcup, "還剩下" + days + "天");
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appWidgetManager.updateAppWidget(widget, remoteViews);
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}
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public LYTimeTask(Context context, AppWidgetManager appWidgetManger) {
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super();
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this.appWidgetManager = appWidgetManger;
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remoteViews = new RemoteViews(context.getPackageName(), R.layout.activity_main);
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widget = new ComponentName(context, MainActivity.class);
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}
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};
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}
>>3、爲Widget創建一個顯示用的佈局文件:main.xml
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
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android:layout_width="match_parent"
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android:layout_height="match_parent"
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android:background="@drawable/worldcup"
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android:orientation="vertical" >
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<TextView
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android:id="@+id/babybirthday"
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android:layout_width="fill_parent"
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android:layout_height="wrap_content"
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android:text="@string/message"
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android:textSize="12px"
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android:textColor="#ff0000" />
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</LinearLayout>
>>4、修改程序自動生成的清單文件。在AndroidManifest.xml中,聲明上述的AppWidgetProvider的子類是一個Receiver,並且:
(1)、該Receiver的intent-filter的Action必須包含“Android.appwidget.action.APPWIDGET_UPDATE”;
(2)、該Receiver的meta-data爲“android.appwidget.provider”,並用一個xml文件來描述佈局屬性。
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<application
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android:allowBackup="true"
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android:icon="@drawable/ic_launcher"
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android:label="@string/app_name"
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android:theme="@style/AppTheme" >
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<receiver
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android:name=".MainActivity"
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android:label="@string/app_name" >
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<intent-filter>
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<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
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</intent-filter>
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<meta-data
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android:name="android.appwidget.provider"
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android:resource="@xml/AppWigdetProvider_Provider" />
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</receiver>
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</application>
運行程序:進入WIDGETS頁面,可將Widget添加到HOME頁
在AppWidgetProvider類中,還有其它相關的方法
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public class WidgetProvider extends AppWidgetProvider {
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public void onReceive(Context context, Intent intent) {
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super.onReceive(context, intent);
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}
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public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
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super.onUpdate(context, appWidgetManager, appWidgetIds);
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}
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public void onDeleted(Context context, int[] appWidgetIds) {
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super.onDeleted(context, appWidgetIds);
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}
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public void onEnabled(Context context) {
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super.onEnabled(context);
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}
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public void onDisabled(Context context) {
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super.onDisabled(context);
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}
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}
AppWidget本質上是一個AppWidgetHostView;
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AppWidgetProvider definition
meta-data resource to provider.xml
provider xml to layout.xml
create AppWidgetInfo transact();
Launcher和AppWidget交互流程如下:
- Launcher 啓動,開始監聽
- Service send a broadcast
- myApp 接收到廣播,執行onUpdate方法
- onUpdate方法回傳RemoteViews給Service
- Service改變Host,updateAppWidget
- Launcher監聽到,更新Appwidget