Android Am命令解析

前言

在Android中，除了从界面上启动程序之外，还可以从命令行启动程序。

相信大家对adb命令非常的熟悉。命令窗口通过adb bash 进入Android 的Linux命令行终端，输入am -help看到如下信息：

C:\Users\yezhou>adb bash
bash@cancro:/ $ am -help
usage: am [subcommand] [options]
usage: am start [-D] [-W] [-P <FILE>] [--start-profiler <FILE>]
               [--sampling INTERVAL] [-R COUNT] [-S] [--opengl-trace]
               [--user <USER_ID> | current] <INTENT>
       am startservice [--user <USER_ID> | current] <INTENT>
       am stopservice [--user <USER_ID> | current] <INTENT>
       am force-stop [--user <USER_ID> | all | current] <PACKAGE>
       am kill [--user <USER_ID> | all | current] <PACKAGE>
       am kill-all
       am broadcast [--user <USER_ID> | all | current] <INTENT>
       am instrument [-r] [-e <NAME> <VALUE>] [-p <FILE>] [-w]
               [--user <USER_ID> | current]
               [--no-window-animation] [--abi <ABI>] <COMPONENT>
       am profile start [--user <USER_ID> current] [--sampling INTERVAL] <PROCESS> <FILE>
       am profile stop [--user <USER_ID> current] [<PROCESS>]
       am dumpheap [--user <USER_ID> current] [-n] <PROCESS> <FILE>
       am set-debug-app [-w] [--persistent] <PACKAGE>
       am clear-debug-app
       am set-watch-heap <PROCESS> <MEM-LIMIT>
       am clear-watch-heap
       am monitor [--gdb <port>]
       am hang [--allow-restart]
       am restart
       am idle-maintenance
       am screen-compat [on|off] <PACKAGE>
       am package-importance <PACKAGE>
       am to-uri [INTENT]
       am to-intent-uri [INTENT]
       am to-app-uri [INTENT]
       am switch-user <USER_ID>
       am start-user <USER_ID>
       am stop-user [-w] <USER_ID>
       am stack start <DISPLAY_ID> <INTENT>
       am stack movetask <TASK_ID> <STACK_ID> [true|false]
       am stack resize <STACK_ID> <LEFT,TOP,RIGHT,BOTTOM>
       am stack split <STACK_ID> <v|h> [INTENT]
       am stack list
       am stack info <STACK_ID>
       am task lock <TASK_ID>
       am task lock stop
       am task resizeable <TASK_ID> [true|false]
       am task resize <TASK_ID> <LEFT,TOP,RIGHT,BOTTOM>
       am get-config
       am set-inactive [--user <USER_ID>] <PACKAGE> true|false
       am get-inactive [--user <USER_ID>] <PACKAGE>
       am send-trim-memory [--user <USER_ID>] <PROCESS>
               [HIDDEN|RUNNING_MODERATE|BACKGROUND|RUNNING_LOW|MODERATE|RUNNING_CRITICAL|COMPLETE]

am start: start an Activity.  Options are:
    -D: enable debugging
    -W: wait for launch to complete
    --start-profiler <FILE>: start profiler and send results to <FILE>
    --sampling INTERVAL: use sample profiling with INTERVAL microseconds
        between samples (use with --start-profiler)
    -P <FILE>: like above, but profiling stops when app goes idle
    -R: repeat the activity launch <COUNT> times.  Prior to each repeat,
        the top activity will be finished.
    -S: force stop the target app before starting the activity
    --opengl-trace: enable tracing of OpenGL functions
    --user <USER_ID> | current: Specify which user to run as; if not
        specified then run as the current user.

am startservice: start a Service.  Options are:
    --user <USER_ID> | current: Specify which user to run as; if not
        specified then run as the current user.

am stopservice: stop a Service.  Options are:
    --user <USER_ID> | current: Specify which user to run as; if not
        specified then run as the current user.

am force-stop: force stop everything associated with <PACKAGE>.
    --user <USER_ID> | all | current: Specify user to force stop;
        all users if not specified.

am kill: Kill all processes associated with <PACKAGE>.  Only kills.
  processes that are safe to kill -- that is, will not impact the user
  experience.
    --user <USER_ID> | all | current: Specify user whose processes to kill;
        all users if not specified.

am kill-all: Kill all background processes.

am broadcast: send a broadcast Intent.  Options are:
    --user <USER_ID> | all | current: Specify which user to send to; if not
        specified then send to all users.
    --receiver-permission <PERMISSION>: Require receiver to hold permission.

am instrument: start an Instrumentation.  Typically this target <COMPONENT>
  is the form <TEST_PACKAGE>/<RUNNER_CLASS>.  Options are:
    -r: print raw results (otherwise decode REPORT_KEY_STREAMRESULT).  Use with
        [-e perf true] to generate raw output for performance measurements.
    -e <NAME> <VALUE>: set argument <NAME> to <VALUE>.  For test runners a
        common form is [-e <testrunner_flag> <value>[,<value>...]].
    -p <FILE>: write profiling data to <FILE>
    -w: wait for instrumentation to finish before returning.  Required for
        test runners.
    --user <USER_ID> | current: Specify user instrumentation runs in;
        current user if not specified.
    --no-window-animation: turn off window animations while running.
    --abi <ABI>: Launch the instrumented process with the selected ABI.
        This assumes that the process supports the selected ABI.

am profile: start and stop profiler on a process.  The given <PROCESS> argument
  may be either a process name or pid.  Options are:
    --user <USER_ID> | current: When supplying a process name,
        specify user of process to profile; uses current user if not specified.

am dumpheap: dump the heap of a process.  The given <PROCESS> argument may
  be either a process name or pid.  Options are:
    -n: dump native heap instead of managed heap
    --user <USER_ID> | current: When supplying a process name,
        specify user of process to dump; uses current user if not specified.

am set-debug-app: set application <PACKAGE> to debug.  Options are:
    -w: wait for debugger when application starts
    --persistent: retain this value

am clear-debug-app: clear the previously set-debug-app.

am set-watch-heap: start monitoring pss size of <PROCESS>, if it is at or
    above <HEAP-LIMIT> then a heap dump is collected for the user to report

am clear-watch-heap: clear the previously set-watch-heap.

am bug-report: request bug report generation; will launch UI
    when done to select where it should be delivered.

am monitor: start monitoring for crashes or ANRs.
    --gdb: start gdbserv on the given port at crash/ANR

am hang: hang the system.
    --allow-restart: allow watchdog to perform normal system restart

am restart: restart the user-space system.

am idle-maintenance: perform idle maintenance now.

am screen-compat: control screen compatibility mode of <PACKAGE>.

am package-importance: print current importance of <PACKAGE>.

am to-uri: print the given Intent specification as a URI.

am to-intent-uri: print the given Intent specification as an intent: URI.

am to-app-uri: print the given Intent specification as an android-app: URI.

am switch-user: switch to put USER_ID in the foreground, starting
  execution of that user if it is currently stopped.

am start-user: start USER_ID in background if it is currently stopped,
  use switch-user if you want to start the user in foreground.

am stop-user: stop execution of USER_ID, not allowing it to run any
  code until a later explicit start or switch to it.
  -w: wait for stop-user to complete.

am stack start: start a new activity on <DISPLAY_ID> using <INTENT>.

am stack movetask: move <TASK_ID> from its current stack to the top (true) or   bottom (false) of <STACK_ID>.

am stack resize: change <STACK_ID> size and position to <LEFT,TOP,RIGHT,BOTTOM>.

am stack split: split <STACK_ID> into 2 stacks <v>ertically or <h>orizontally
   starting the new stack with [INTENT] if specified. If [INTENT] isn't
   specified and the current stack has more than one task, then the top task
   of the current task will be moved to the new stack. Command will also force
   all current tasks in both stacks to be resizeable.

am stack list: list all of the activity stacks and their sizes.

am stack info: display the information about activity stack <STACK_ID>.

am task lock: bring <TASK_ID> to the front and don't allow other tasks to run.

am task lock stop: end the current task lock.

am task resizeable: change if <TASK_ID> is resizeable (true) or not (false).

am task resize: makes sure <TASK_ID> is in a stack with the specified bounds.
   Forces the task to be resizeable and creates a stack if no existing stack
   has the specified bounds.

am get-config: retrieve the configuration and any recent configurations
  of the device.

am set-inactive: sets the inactive state of an app.

am get-inactive: returns the inactive state of an app.

am send-trim-memory: Send a memory trim event to a <PROCESS>.

<INTENT> specifications include these flags and arguments:
    [-a <ACTION>] [-d <DATA_URI>] [-t <MIME_TYPE>]
    [-c <CATEGORY> [-c <CATEGORY>] ...]
    [-e|--es <EXTRA_KEY> <EXTRA_STRING_VALUE> ...]
    [--esn <EXTRA_KEY> ...]
    [--ez <EXTRA_KEY> <EXTRA_BOOLEAN_VALUE> ...]
    [--ei <EXTRA_KEY> <EXTRA_INT_VALUE> ...]
    [--el <EXTRA_KEY> <EXTRA_LONG_VALUE> ...]
    [--ef <EXTRA_KEY> <EXTRA_FLOAT_VALUE> ...]
    [--eu <EXTRA_KEY> <EXTRA_URI_VALUE> ...]
    [--ecn <EXTRA_KEY> <EXTRA_COMPONENT_NAME_VALUE>]
    [--eia <EXTRA_KEY> <EXTRA_INT_VALUE>[,<EXTRA_INT_VALUE...]]
        (mutiple extras passed as Integer[])
    [--eial <EXTRA_KEY> <EXTRA_INT_VALUE>[,<EXTRA_INT_VALUE...]]
        (mutiple extras passed as List<Integer>)
    [--ela <EXTRA_KEY> <EXTRA_LONG_VALUE>[,<EXTRA_LONG_VALUE...]]
        (mutiple extras passed as Long[])
    [--elal <EXTRA_KEY> <EXTRA_LONG_VALUE>[,<EXTRA_LONG_VALUE...]]
        (mutiple extras passed as List<Long>)
    [--efa <EXTRA_KEY> <EXTRA_FLOAT_VALUE>[,<EXTRA_FLOAT_VALUE...]]
        (mutiple extras passed as Float[])
    [--efal <EXTRA_KEY> <EXTRA_FLOAT_VALUE>[,<EXTRA_FLOAT_VALUE...]]
        (mutiple extras passed as List<Float>)
    [--esa <EXTRA_KEY> <EXTRA_STRING_VALUE>[,<EXTRA_STRING_VALUE...]]
        (mutiple extras passed as String[]; to embed a comma into a string,
         escape it using "\,")
    [--esal <EXTRA_KEY> <EXTRA_STRING_VALUE>[,<EXTRA_STRING_VALUE...]]
        (mutiple extras passed as List<String>; to embed a comma into a string,
         escape it using "\,")
    [--grant-read-uri-permission] [--grant-write-uri-permission]
    [--grant-persistable-uri-permission] [--grant-prefix-uri-permission]
    [--debug-log-resolution] [--exclude-stopped-packages]
    [--include-stopped-packages]
    [--activity-brought-to-front] [--activity-clear-top]
    [--activity-clear-when-task-reset] [--activity-exclude-from-recents]
    [--activity-launched-from-history] [--activity-multiple-task]
    [--activity-no-animation] [--activity-no-history]
    [--activity-no-user-action] [--activity-previous-is-top]
    [--activity-reorder-to-front] [--activity-reset-task-if-needed]
    [--activity-single-top] [--activity-clear-task]
    [--activity-task-on-home]
    [--receiver-registered-only] [--receiver-replace-pending]
    [--selector]
    [<URI> | <PACKAGE> | <COMPONENT>]

Error: unknown command '-help'
bash@cancro:/ $

什么是am命令

am全称ActivityManager，是Android下Linux终端的一个命令行工具。可以使用am去模拟各种系统的行为，例如启动一个Activity，强制停止进程，发送广播进程，修改设备屏幕属性等等。

• 拨打电话10086

am start -a android.intent.action.CALL -d tel:10086

• 打开网站http://www.appblog.cn

am start -a android.intent.action.VIEW -d  http://www.appblog.cn

• 启动Activity

am start -n me.yezhou.algorithm/.WelcomeActivity

主要的启动Activity命令

am start [options] 使用options参数，接下来列举Activity命令的[options]参数：

• -D: 允许调试功能
• -W: 等待App启动完成
• --start-profiler : 启动profiler，并将结果发送到
• --sampling INTERVAL: 设置profiler 取样时间间隔，单位ms
• -P: 类似 –start-profiler，不同的是当app进入idle状态，则停止profiling
• -R: 重复启动Activity COUNT次
• -S: 启动Activity之前，先调用forceStopPackage()方法强制停止App
• –opengl-trace: 运行获取OpenGL函数的trace
  – user | current: 指定用户来运行App，默认为当前用户。

启动Activity的实现原理

存在-W参数则调用startActivityAndWait()方法来运行，否则startActivityAsUser()。

• 打开音乐播放器：

am start -a android.intent.action.MUSIC_PLAYER

• 启动一个服务：

am startservice -n com.android.music/com.android.music.MediaPlaybackService (这里-n表示组件)
//或者
am startservice -a cn.appblog.MyService (-a表示动作，就是在Androidmanifest里定义的)

• 发送一个广播：

am broadcast -a cn.appblog.MyBroadcast

am的相关参数

• a: 指定Intent action， 实现原理Intent.setAction()；
• n: 指定组件名，格式为{包名}/.{主Activity名}，实现原理Intent.setComponent()；
• d: 指定Intent Data URI
• t: 指定Intent MIME Type
• c: 指定Intent Category，实现原理Intent.addCategory()
• p: 指定包名，实现原理Intent.setPackage();
• f: 添加flags，实现原理Intent.setFlags(int)，紧接着的参数必须是int型；

am命令实的实现方式

am命令实的实现方式在Am.java，最终几乎都是调用ActivityManagerService相应的方法来完成的，am monitor除外。

比如前面概述中介绍的命令am start -a android.intent.action.VIEW -d http://www.appblog.cn， 启动Acitivty最终调用的是ActivityManagerService类的startActivityAsUser()方法来完成的。

再比如am kill-all命令，最终的实现工作是由ActivityManagerService的killBackgroundProcesses()方法完成的。

收紧内存

命令

am send-trim-memory  <pid> <level>

例如：向pid=12345的进程，发出level=RUNNING_LOW的收紧内存命令

am send-trim-memory 12345 RUNNING_LOW

level取值范围为：

• HIDDEN
• RUNNING_MODERATE
• BACKGROUND
• RUNNING_LOW
• MODERATE
• RUNNING_CRITICAL
• COMPLETE