前述

初次涉猎Android程序，使用 Xamarin 编写，这里不讨论 Xamarin 的好坏，重点是解决我们的问题。调用系统功能必不可少的便是 adb 命令和 Android 共享库，来浅试下。

pm 命令

pm工具为包管理（package manager）的简称。
可以使用 pm 工具来执行应用的安装和查询应用包的信息、系统权限、控制应用。
pm 工具是 Android 开发与测试过程中必不可少的工具。
命令格式：pm <command>

命令行下输入 adb shell pm 即可获得关于 pm 的用法帮助

usage: pm list packages [-f] [-d] [-e] [-s] [-3] [-i] [-u] [--user USER_ID] [FILTER]pm list permission-groupspm list permissions [-g] [-f] [-d] [-u] [GROUP]pm list instrumentation [-f] [TARGET-PACKAGE]pm list featurespm list librariespm list userspm path PACKAGEpm dump PACKAGEpm install [-lrtsfd] [-i PACKAGE] [PATH]pm install-create [-lrtsfdp] [-i PACKAGE] [-S BYTES]pm install-write [-S BYTES] SESSION_ID SPLIT_NAME [PATH]pm install-commit SESSION_IDpm install-abandon SESSION_IDpm uninstall [-k] [--user USER_ID] PACKAGEpm set-installer PACKAGE INSTALLERpm clear [--user USER_ID] PACKAGEpm enable [--user USER_ID] PACKAGE_OR_COMPONENTpm disable [--user USER_ID] PACKAGE_OR_COMPONENTpm disable-user [--user USER_ID] PACKAGE_OR_COMPONENTpm disable-until-used [--user USER_ID] PACKAGE_OR_COMPONENTpm hide [--user USER_ID] PACKAGE_OR_COMPONENTpm unhide [--user USER_ID] PACKAGE_OR_COMPONENTpm grant PACKAGE PERMISSIONpm revoke PACKAGE PERMISSIONpm set-install-location [0/auto] [1/internal] [2/external]pm get-install-locationpm set-permission-enforced PERMISSION [true|false]pm trim-caches DESIRED_FREE_SPACEpm create-user [--profileOf USER_ID] [--managed] USER_NAMEpm remove-user USER_IDpm get-max-userspm list packages: prints all packages, optionally onlythose whose package name contains the text in FILTER.  Options:-f: see their associated file.-d: filter to only show disbled packages.-e: filter to only show enabled packages.-s: filter to only show system packages.-3: filter to only show third party packages.-i: see the installer for the packages.-u: also include uninstalled packages.pm list permission-groups: prints all known permission groups.pm list permissions: prints all known permissions, optionally onlythose in GROUP.  Options:-g: organize by group.-f: print all information.-s: short summary.-d: only list dangerous permissions.-u: list only the permissions users will see.pm list instrumentation: use to list all test packages; optionallysupply <TARGET-PACKAGE> to list the test packages for a particularapplication.  Options:-f: list the .apk file for the test package.pm list features: prints all features of the system.pm list users: prints all users on the system.pm path: print the path to the .apk of the given PACKAGE.pm dump: print system state associated with the given PACKAGE.pm install: install a single legacy package
pm install-create: create an install session-l: forward lock application-r: replace existing application-t: allow test packages-i: specify the installer package name-s: install application on sdcard-f: install application on internal flash-d: allow version code downgrade-p: partial application install-S: size in bytes of entire sessionpm install-write: write a package into existing session; path maybe '-' to read from stdin-S: size in bytes of package, required for stdinpm install-commit: perform install of fully staged session
pm install-abandon: abandon sessionpm set-installer: set installer package namepm uninstall: removes a package from the system. Options:-k: keep the data and cache directories around after package removal.pm clear: deletes all data associated with a package.pm enable, disable, disable-user, disable-until-used: these commandschange the enabled state of a given package or component (writtenas "package/class").pm grant, revoke: these commands either grant or revoke permissionsto applications.  Only optional permissions the application hasdeclared can be granted or revoked.pm get-install-location: returns the current install location.0 [auto]: Let system decide the best location1 [internal]: Install on internal device storage2 [external]: Install on external mediapm set-install-location: changes the default install location.NOTE: this is only intended for debugging; using this can causeapplications to break and other undersireable behavior.0 [auto]: Let system decide the best location1 [internal]: Install on internal device storage2 [external]: Install on external mediapm trim-caches: trim cache files to reach the given free space.pm create-user: create a new user with the given USER_NAME,printing the new user identifier of the user.pm remove-user: remove the user with the given USER_IDENTIFIER,deleting all data associated with that user

Context

Context 提供了关于应用环境全局信息的接口。它是一个抽象类，它的执行被Android系统所提供。它允许获取以应用为特征的资源和类型，是一个统领一些资源（应用程序环境变量等）的上下文。

也就是说Context描述一个应用程序环境的信息（即上下文）；是一个抽象类，Android提供了该抽象类的具体实现类；通过它我们可以获取应用程序的资源和类。

下面的代码中使用到了 _context 对象这里交代下

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{internal static MainActivity Instance { get; private set; }
}// 在各自的实现类中定义然后使用
private readonly Context _context = MainActivity.Instance;

命令执行

执行命令前需要获取 su 权限

using Java.IO;private bool ExecuteCommand(string commandStr)
{try{using Process p = Runtime.GetRuntime().Exec("su");BufferedReader ins = new BufferedReader(new InputStreamReader(p.InputStream));BufferedReader ie = new BufferedReader(new InputStreamReader(p.ErrorStream));BufferedWriter w = new BufferedWriter(new OutputStreamWriter(p.OutputStream));w.Write(commandStr);w.Flush();w.Close();ins.Close();ie.Close();int res = p.WaitFor();if (res is 0)return true;}catch (Throwable ex){return false;}return false;
}

检查应用是否安装

检查 APP 是否安装，PackageManager 实例来获取当前系统安装的所有 APP 通过packageName 进行判断。

public bool CheckAppInstalled(string packageName)
{var packageInfo = _context.PackageManager.GetInstalledPackages(PackageInfoFlags.Activities).Where(pm => pm.PackageName == packageName).FirstOrDefault();if (packageInfo != null)return true;return false;
}

设置自动开关机

自动开关机，就属于 Android 共享库实现了 Android Intent，具体怎么用自己搜很多，这里把开关机时间的设定作为例子。

需要指定共享库的操作函数，用常量存下

/// <summary>
/// 开机 Intent
/// </summary>
private static readonly string SETPOWERON = "android.intent.action.setpoweron";
/// <summary>
/// 关机 Intent
/// </summary>
private static readonly string SETPOWEROFF = "android.intent.action.setpoweroff";

代码实现，需要注意的是时间，它是个 long 类型需要进行转换

private static readonly string SETPOWERON = "android.intent.action.setpoweron";
private static readonly string SETPOWEROFF = "android.intent.action.setpoweroff";
private static readonly string POWERON = "poweron";
private static readonly string POWEROFF = "poweroff";
private static readonly string ENABLE = "enable";public bool PowerOffPlan(bool enable, long planTime)
{try{Intent intent = new Intent(SETPOWEROFF);intent.PutExtra(ENABLE, enable);if (enable && planTime > 0){Date dateTime = new Date(planTime);Calendar calendar = Calendar.GetInstance(Locale.SimplifiedChinese);calendar.Time = dateTime;calendar.Set(CalendarField.Second, 0);int[] time = new int[]{calendar.Get(CalendarField.Year),calendar.Get(CalendarField.Month),calendar.Get(CalendarField.DayOfMonth),calendar.Get(CalendarField.HourOfDay),calendar.Get(CalendarField.Minute),calendar.Get(CalendarField.Second),};intent.PutExtra(POWEROFF, time);}_context.SendBroadcast(intent);return true;}catch (Throwable ex){Toast.MakeText(_context, $"Exception：{ex.Message}", ToastLength.Short).Show();}return false;
}public bool PowerOnPlan(bool enable, long planTime)
{try{Intent intent = new Intent(SETPOWERON);intent.PutExtra(ENABLE, enable);if (enable && planTime > 0){Date dateTime = new Date(planTime);Calendar calendar = Calendar.GetInstance(Locale.SimplifiedChinese);calendar.Time = dateTime;calendar.Set(CalendarField.Second, 0);int[] time = new int[]{calendar.Get(CalendarField.Year),calendar.Get(CalendarField.Month),calendar.Get(CalendarField.DayOfMonth),calendar.Get(CalendarField.HourOfDay),calendar.Get(CalendarField.Minute),calendar.Get(CalendarField.Second),};intent.PutExtra(POWERON, time);}_context.SendBroadcast(intent);return true;}catch (Throwable ex){Toast.MakeText(_context, $"Exception：{ex.Message}", ToastLength.Short).Show();}return false;
}

开机自启动

通过监听系统的开机广播来实现，拉起app。
首先，需要在清单文件AndroidManifest.xml申请监听开机广播权限
android.intent.action.BOOT_COMPLETED

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

然后在清单文件 AndroidManifest.xml 声明该广播接收者，也就是下面实现监听广播处理自己的业务逻辑（拉起自己app）的类 BootReceiver

<receiver android:name=".base.BootReceiver"><intent-filter><action android:name="android.intent.action.BOOT_COMPLETED" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter>
</receiver>

最后实现一个BroadcastReceiver，该广播接收者监听"android.intent.action.BOOT_COMPLETED"广播，当接收到该广播时，打开该应用的启动页面。

[BroadcastReceiver(Enabled = true)]
[IntentFilter(new[] { Intent.ActionBootCompleted, Intent.ActionReboot })]
public class BootReceiver : BroadcastReceiver
{public override void OnReceive(Context context, Intent intent){try{if (intent.Action != null && intent.Action is Intent.ActionBootCompleted){Intent _intent = new Intent();_intent.SetClass(context, typeof(MainActivity));_intent.SetFlags(ActivityFlags.NewTask);context.StartService(_intent);}}catch (System.Exception ex){Toast.MakeText(context, ex.Message, ToastLength.Short).Show();}}
}

这种开机自启的方式不好的地方在于，需要在安装之后手动启动一下，才能收听广播。如果有好的方案，请不吝赐教

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Xamarin.Forsm for Android 系统功能

Xamarin.Forsm for Android 系统功能

前述

pm 命令

Context

命令执行

检查应用是否安装

设置自动开关机

开机自启动

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