android Activity启动模式

时间  2019-11-07
标签 android activity 启动 模式 栏目 Android 繁體版
原文   原文链接

Activity的启动模式有两种：一种是在AndroidManifest.xml文件中，配置launchMode属性，还有一种是设置intent的flag的方式来启动java

一、设置android:launchMode属性

    能够分为四种：standard、singleTop、singleTask、singleInstanceandroid

    standard：默认值。系统不考虑此Activity的实例是否已经在Back Stack中存在。每次建立都会启动一个新的Activityshell

    singleTop:启动时，栈顶恰好就是目标Activity,则调用此Activity的onNewIntent()便可。若是不是，则建立新的Activity实例spa

    singleTask:整个应用程序的上下文只有一个实例。当启动此类Activity的时候，系统会从Back Stack中检查是否已经存在此Activity的实例。            若是存在，会直接使用，并将此实例之上的Activity出栈，依然会毁掉onNewIntent().若是没有就会建立一个新的实例。翻译

    singleInstance:此Activity独享一个Back Stack。主要用于程序之间的数据共享。code

    下面以例子来解释：xml

    具体的代码的设定模式以下：生命周期

<activity
            android:name=".launchmodeTest.StandardAActivity"
            android:label="A">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".launchmodeTest.SingleTopActivity" android:launchMode="singleTop" android:label="栈顶复用"/>
        <activity android:name=".launchmodeTest.SingleTaskActivity" android:launchMode="singleTask" android:label="栈内复用"/>
        <activity android:name=".launchmodeTest.SingleInstanceActivity" android:launchMode="singleInstance" android:label="单独的一个栈"/>
        <activity android:name=".launchmodeTest.StandardCActivity" android:label="C"></activity>

   1.1 singleTop 栈顶复用：

            1.1.1 启动步骤为：StandardAActivity-->SingleTopActivity-->StandardCActivity-->SingleTopActivity进程

                执行adb shell dumpsys activity命令，在堆栈中的代码为（截取了其中一部分）：字符串

Running activities (most recent first):
    TaskRecord{528b8768 #5 A base.example.com U 0}
      Run #4: ActivityRecord{528ddc64 u0 base.example.com/.launchmodeTest.SingleTopActivity}
      Run #3: ActivityRecord{52897c50 u0 base.example.com/.launchmodeTest.StandardCActivity}
      Run #2: ActivityRecord{5288e658 u0 base.example.com/.launchmodeTest.SingleTopActivity}
      Run #1: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

         分析说明：

                a、其中有两个堆栈：

                    前台堆栈：TaskRecord{528d7cd8 #6 A base.example.com U 0}

                    后台堆栈：TaskRecord{528c8b7c #2 A com.android.launcher U 0}

                b、桌面：Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

        1.1.2 启动步骤为：StandardAActivity-->SingleTopActivity-->SingleTopActivity

                执行adb shell dumpsys activity命令，在堆栈中的代码为（截取了其中一部分）：

Running activities (most recent first):
    TaskRecord{528d7cd8 #6 A base.example.com U 0}
      Run #2: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.SingleTopActivity}
      Run #1: ActivityRecord{528b78c0 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                能够看到，SingleTopActivity两次启动，可是只有一个实例。

                其中，生命周期为

11-28 03:22:01.499 1831-1831/base.example.com I/SingleTopActivity: onPause: 
11-28 03:22:01.499 1831-1831/base.example.com I/SingleTopActivity: onNewIntent: 
11-28 03:22:01.499 1831-1831/base.example.com I/SingleTopActivity: onResume:

            1.2  singleTask 栈内复用

                   启动步骤为：StandardAActivity-->SingleTaskActivity-->StandardCActivity   

                   堆栈为：

Running activities (most recent first):
    TaskRecord{528764c0 #8 A base.example.com U 0}
      Run #3: ActivityRecord{5289a4a0 u0 base.example.com/.launchmodeTest.StandardCActivity}
      Run #2: ActivityRecord{52889940 u0 base.example.com/.launchmodeTest.SingleTaskActivity}
      Run #1: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                   再启动SingleTaskActivity

                   堆栈为： 

Running activities (most recent first):
    TaskRecord{528764c0 #8 A base.example.com U 0}
      Run #2: ActivityRecord{52889940 u0 base.example.com/.launchmodeTest.SingleTaskActivity}
      Run #1: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

            可见，其中StandardCActivity被从堆栈中移除，其生命周期为：

11-28 04:13:09.295 2163-2163/base.example.com I/StandardCActivity: onPause: 
11-28 04:13:09.311 2163-2163/base.example.com I/SingleTaskActivity: onNewIntent: 
11-28 04:13:09.311 2163-2163/base.example.com I/SingleTaskActivity: onStart: 
11-28 04:13:09.311 2163-2163/base.example.com I/SingleTaskActivity: onResume: 
11-28 04:13:09.343 2163-2163/base.example.com W/EGL_genymotion: eglSurfaceAttrib not implemented
11-28 04:13:09.719 2163-2163/base.example.com I/StandardCActivity: onStop: 
11-28 04:13:09.719 2163-2163/base.example.com I/StandardCActivity: onDestroy:

        可见，直接将SingleTaskActivity上面的StandardCActivity移除，并调用了本身的onNewIntent()方法。StandardCActivity本身走了本身的destroy流程。（栈内复用）

            1.2.1 使用taskAffinity属性

                    taskAffinity属性能够翻译为任务相关性，主要表示的是此Activity的进程名字（默认进程是包名）。其中的值必须为字符串，而且包含“.”

                    例如以下定义：

<activity android:name=".launchmodeTest.SingleTaskWithAffinityActivity"
            android:launchMode="singleTask" android:taskAffinity="com.cxy.test"></activity>

                    启动后的栈为：StandardAActivity-->SingleTaskWithAffinityActivity

Running activities (most recent first):
    TaskRecord{528e7e2c #12 A com.cxy.test U 0}
      Run #2: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.SingleTaskWithAffinityActivity}
    TaskRecord{528c7a48 #11 A base.example.com U 0}
      Run #1: ActivityRecord{5276bcd4 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                    再启动一个standard模式的Activity:StandardAActivity-->SingleTaskWithAffinityActivity-->StandardCActivity

Running activities (most recent first):
    TaskRecord{528e7e2c #12 A com.cxy.test U 0}
      Run #3: ActivityRecord{52889940 u0 base.example.com/.launchmodeTest.StandardCActivity}
      Run #2: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.SingleTaskWithAffinityActivity}
    TaskRecord{528c7a48 #11 A base.example.com U 0}
      Run #1: ActivityRecord{5276bcd4 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                               能够查看出来，谁启动的Activity，就会在谁的栈中添加对应的Activity。除非被启动的Activity已经制定了进程名。

                    再次启动SingleTaskWithAffinityActivity：StandardAActivity-->SingleTaskWithAffinityActivity-->SingleTaskWithAffinityActivity

Running activities (most recent first):
    TaskRecord{528e7e2c #12 A com.cxy.test U 0}
      Run #2: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.SingleTaskWithAffinityActivity}
    TaskRecord{528c7a48 #11 A base.example.com U 0}
      Run #1: ActivityRecord{5276bcd4 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                    生命周期：

11-28 04:37:02.595 2411-2411/base.example.com I/StandardCActivity: onPause: 
11-28 04:37:02.607 2411-2411/base.example.com I/SingleTaskWithAffinityA: onNewIntent: 
11-28 04:37:02.607 2411-2411/base.example.com I/SingleTaskWithAffinityA: onStart: 
11-28 04:37:02.611 2411-2411/base.example.com I/SingleTaskWithAffinityA: onResume: 
11-28 04:37:02.647 2411-2411/base.example.com W/EGL_genymotion: eglSurfaceAttrib not implemented
11-28 04:37:03.019 2411-2411/base.example.com I/StandardCActivity: onStop: 
11-28 04:37:03.019 2411-2411/base.example.com I/StandardCActivity: onDestroy:

                                可见调用了SingleTaskWithAffinityActivity的onNewIntent()、onStart()、onResume()方法。并将StandardCActivity从堆栈中移除了。

                    再次启动SingleTaskActivity：StandardAActivity-->SingleTaskWithAffinityActivity-->StandardCActivity-->SingleTaskActivity

Running activities (most recent first):
    TaskRecord{528321b0 #13 A base.example.com U 0}
      Run #4: ActivityRecord{5292dca8 u0 base.example.com/.launchmodeTest.SingleTaskActivity}
    TaskRecord{5288a210 #14 A com.cxy.test U 0}
      Run #3: ActivityRecord{528ddc64 u0 base.example.com/.launchmodeTest.StandardCActivity}
      Run #2: ActivityRecord{5288e658 u0 base.example.com/.launchmodeTest.SingleTaskWithAffinityActivity}
    TaskRecord{528321b0 #13 A base.example.com U 0}
      Run #1: ActivityRecord{52889940 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                                可见设置了singleTask模式的activity，会在原来的堆栈中。

                    假设给standard模式的activity设置taskAffinity属性

<activity
            android:name=".launchmodeTest.StandardCActivity"
            android:label="C"
            android:taskAffinity="com.cxy.test.one"/>

                            启动的结果为：StandardAActivity-->SingleTaskWithAffinityActivity-->StandardCActivity

Running activities (most recent first):
    TaskRecord{5276b448 #16 A com.cxy.test U 0}
      Run #3: ActivityRecord{5288e658 u0 base.example.com/.launchmodeTest.StandardCActivity}
      Run #2: ActivityRecord{528ddc64 u0 base.example.com/.launchmodeTest.SingleTaskWithAffinityActivity}
    TaskRecord{528d42c4 #15 A base.example.com U 0}
      Run #1: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                            taskAffinity必须与singleTask模式使用，才会有效果。（书上说的，须要本身去验证）

        1.3  singleInstance单实例模式

               如下涉及到的activity的定义：

<activity
            android:name=".launchmodeTest.StandardAActivity"
            android:label="A">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".launchmodeTest.SingleTopActivity"
            android:label="栈顶复用"
            android:launchMode="singleTop" />
        <activity
            android:name=".launchmodeTest.SingleTaskActivity"
            android:label="栈内复用"
            android:launchMode="singleTask" />
        <activity
            android:name=".launchmodeTest.SingleInstanceActivity"
            android:label="单独的一个栈"
            android:launchMode="singleInstance" />
        <activity
            android:name=".launchmodeTest.StandardCActivity"
            android:label="C"/>
        <activity android:name=".launchmodeTest.SingleTaskWithAffinityActivity"
            android:launchMode="singleTask" android:taskAffinity="com.cxy.test"></activity>

               1.3.1 在普通Activity跳转到singleInstance的Activity

                            StandardAActivity-->SingleInstanceActivity

Running activities (most recent first):
    TaskRecord{52885efc #18 A base.example.com U 0}
      Run #2: ActivityRecord{52937648 u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{52897aa0 #17 A base.example.com U 0}
      Run #1: ActivityRecord{528a6334 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                            直接新启动了一个编号为18的任务栈来单独存放，并做为前台任务栈

                        1.3.1.1 在singleInstance的Activity跳转到普通Activity

                                         StandardAActivity-->SingleInstanceActivity-->StandardCActivity

Running activities (most recent first):
    TaskRecord{52897aa0 #17 A base.example.com U 0}
      Run #3: ActivityRecord{52905030 u0 base.example.com/.launchmodeTest.StandardCActivity}
    TaskRecord{52885efc #18 A base.example.com U 0}
      Run #2: ActivityRecord{52937648 u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{52897aa0 #17 A base.example.com U 0}
      Run #1: ActivityRecord{528a6334 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                        1.3.1.2 点击返回按钮

Running activities (most recent first):
    TaskRecord{52897aa0 #17 A base.example.com U 0}
      Run #2: ActivityRecord{528a6334 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{52885efc #18 A base.example.com U 0}
      Run #1: ActivityRecord{52937648 u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                         1.3.1.2 点击返回按钮

Running activities (most recent first):
    TaskRecord{52885efc #18 A base.example.com U 0}
      Run #1: ActivityRecord{52937648 u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

               1.3.2 在singleInstance的Activity跳转到SingleTop的Activity

                            StandardAActivity-->SingleInstanceActivity-->SingleTopActivity

Running activities (most recent first):
    TaskRecord{528864b0 #21 A base.example.com U 0}
      Run #3: ActivityRecord{5288e658 u0 base.example.com/.launchmodeTest.SingleTopActivity}
    TaskRecord{5289313c #22 A base.example.com U 0}
      Run #2: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{528864b0 #21 A base.example.com U 0}
      Run #1: ActivityRecord{5276bcd4 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

               1.3.3 在singleInstance的Activity跳转到SingleTask的Activity

                            StandardAActivity-->SingleInstanceActivity-->SingleTaskActivity

Running activities (most recent first):
    TaskRecord{52863e64 #23 A base.example.com U 0}
      Run #3: ActivityRecord{528acda4 u0 base.example.com/.launchmodeTest.SingleTaskActivity}
    TaskRecord{52830620 #24 A base.example.com U 0}
      Run #2: ActivityRecord{528aaa88 u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{52863e64 #23 A base.example.com U 0}
      Run #1: ActivityRecord{528aa754 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

               1.3.4 在singleInstance的Activity跳转到SingleTask+AffinityActivity

                            StandardAActivity-->SingleInstanceActivity-->SingleTaskWithAffinityActivity

Running activities (most recent first):
    TaskRecord{528cbc48 #27 A com.cxy.test U 0}
      Run #3: ActivityRecord{5288e658 u0 base.example.com/.launchmodeTest.SingleTaskWithAffinityActivity}
    TaskRecord{52832ec8 #26 A base.example.com U 0}
      Run #2: ActivityRecord{527919fc u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{528c7cc0 #25 A base.example.com U 0}
      Run #1: ActivityRecord{5276bcd4 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

               1.3.5 在singleInstance的Activity跳转到 singleInstance的Activity

                            StandardAActivity-->SingleInstanceActivity-->SingleInstanceActivity

Running activities (most recent first):
    TaskRecord{528009a8 #29 A base.example.com U 0}
      Run #2: ActivityRecord{528acda4 u0 base.example.com/.launchmodeTest.SingleInstanceActivity}
    TaskRecord{528ac1bc #28 A base.example.com U 0}
      Run #1: ActivityRecord{528aa754 u0 base.example.com/.launchmodeTest.StandardAActivity}
    TaskRecord{528c8b7c #2 A com.android.launcher U 0}
      Run #0: ActivityRecord{528aca90 u0 com.android.launcher/com.android.launcher2.Launcher}

                            对应的生命周期为：

11-28 08:07:00.135 3369-3369/base.example.com I/SingleInstanceActivity: onPause: 
11-28 08:07:00.135 3369-3369/base.example.com I/SingleInstanceActivity: onNewIntent: 
11-28 08:07:00.135 3369-3369/base.example.com I/SingleInstanceActivity: onResume:

                        总结：singleInstance的Activity只会单独存放在一个堆栈中。而且对此启动都不会再次建立，只会调用onNewIntent相关的生命周期方法

二、设置intent的Flag属性

    FLAG_ACTIVITY_NEW_TASK:使用一个新的task来启动Activity。一般使用在service中启动Activity
    FLAG_ACTIVITY_SINGLE_TOP：使用singleTop模式来启动Activity
    FLAG_ACTIVITY_CLEAR_TOP：使用singleTask模式来启动Activity
    FLAG_ACTIVITY_NO_HISTORY:使用此模式启动的Activity,该Activity启动完其余Activity之后，此Activity会从栈中消失

    还有一些其余的属性，须要本身去试一下。

注意：

（1）、在优先级上：以上两种启动模式，设置intent的flag属性的优先级会更高。

（2）、在限定范围上，设置android:launchMode属性这种方式，没法为Activity设定FLAG_ACTIVITY_CLEAR_TOP标志。

        设置intent的Flag属性的方式，没法指定singleInstance的方式。

（3）、非特殊状况，尽可能使用设置android:launchMode属性这种方式

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