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1. 概述

dpm主要是和DevicePolicyManage进行交互,通过用户授权应用设备管理权限后,可以在代码修改很多系统设置。

2. dpm命令

命令格式：
dpm <command>
命令列表：

3. 详细流程

所有adb命令的dpm方法最后都会通过Dpm.java执行,然后通过跨进程调用DevicePolicyManager的方法完成。
流程很简单,在此就不论述了,仅给出Dpm.java文件

public final class Dpm extends BaseCommand {
    /**
     * Command-line entry point.
     *
     * @param args The command-line arguments
     */
    public static void main(String[] args) {
      (new Dpm()).run(args);
    }
    private static final String COMMAND_SET_ACTIVE_ADMIN = "set-active-admin";
    private static final String COMMAND_SET_DEVICE_OWNER = "set-device-owner";
    private static final String COMMAND_SET_PROFILE_OWNER = "set-profile-owner";
    private IDevicePolicyManager mDevicePolicyManager;
    private int mUserId = UserHandle.USER_OWNER;
    private ComponentName mComponent = null;
    @Override
    public void onShowUsage(PrintStream out) {
        out.println(
                "usage: dpm [subcommand] [options]\n" +
                "usage: dpm set-active-admin [ --user <USER_ID> ] <COMPONENT>\n" +
                "usage: dpm set-device-owner <COMPONENT>\n" +
                "usage: dpm set-profile-owner [ --user <USER_ID> ] <COMPONENT>\n" +
                "\n" +
                "dpm set-active-admin: Sets the given component as active admin" +
                " for an existing user.\n" +
                "\n" +
                "dpm set-device-owner: Sets the given component as active admin, and its\n" +
                "  package as device owner.\n" +
                "\n" +
                "dpm set-profile-owner: Sets the given component as active admin and profile" +
                "  owner for an existing user.\n");
    }
    @Override
    public void onRun() throws Exception {
        mDevicePolicyManager = IDevicePolicyManager.Stub.asInterface(
                ServiceManager.getService(Context.DEVICE_POLICY_SERVICE));
        if (mDevicePolicyManager == null) {
            showError("Error: Could not access the Device Policy Manager. Is the system running?");
            return;
        }
        String command = nextArgRequired();
        switch (command) {
            case COMMAND_SET_ACTIVE_ADMIN:
                runSetActiveAdmin();
                break;
            case COMMAND_SET_DEVICE_OWNER:
                runSetDeviceOwner();
                break;
            case COMMAND_SET_PROFILE_OWNER:
                runSetProfileOwner();
                break;
            default:
                throw new IllegalArgumentException ("unknown command '" + command + "'");
        }
    }
    private void parseArgs(boolean canHaveUser) {
        String nextArg = nextArgRequired();
        if (canHaveUser && "--user".equals(nextArg)) {
            mUserId = parseInt(nextArgRequired());
            nextArg = nextArgRequired();
        }
        mComponent = parseComponentName(nextArg);
    }
    private void runSetActiveAdmin() throws RemoteException {
        parseArgs(true);
        mDevicePolicyManager.setActiveAdmin(mComponent, true /*refreshing*/, mUserId);
        System.out.println("Success: Active admin set to component " + mComponent.toShortString());
    }
    private void runSetDeviceOwner() throws RemoteException {
        ComponentName component = parseComponentName(nextArgRequired());
        mDevicePolicyManager.setActiveAdmin(component, true /*refreshing*/, UserHandle.USER_OWNER);
        String packageName = component.getPackageName();
        try {
            if (!mDevicePolicyManager.setDeviceOwner(packageName, null /*ownerName*/)) {
                throw new RuntimeException(
                        "Can't set package " + packageName + " as device owner.");
            }
        } catch (Exception e) {
            // Need to remove the admin that we just added.
            mDevicePolicyManager.removeActiveAdmin(component, UserHandle.USER_OWNER);
            throw e;
        }
        System.out.println("Success: Device owner set to package " + packageName);
        System.out.println("Active admin set to component " + component.toShortString());
    }
    private void runSetProfileOwner() throws RemoteException {
        parseArgs(true);
        mDevicePolicyManager.setActiveAdmin(mComponent, true /*refreshing*/, mUserId);
        try {
            if (!mDevicePolicyManager.setProfileOwner(mComponent, "" /*ownerName*/, mUserId)) {
                throw new RuntimeException("Can't set component " + mComponent.toShortString() +
                        " as profile owner for user " + mUserId);
            }
        } catch (Exception e) {
            // Need to remove the admin that we just added.
            mDevicePolicyManager.removeActiveAdmin(mComponent, mUserId);
            throw e;
        }
        System.out.println("Success: Active admin and profile owner set to "
                + mComponent.toShortString() + " for user " + mUserId);
    }
    private ComponentName parseComponentName(String component) {
        ComponentName cn = ComponentName.unflattenFromString(component);
        if (cn == null) {
            throw new IllegalArgumentException ("Invalid component " + component);
        }
        return cn;
    }
    private int parseInt(String argument) {
        try {
            return Integer.parseInt(argument);
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException ("Invalid integer argument '" + argument + "'", e);
        }
    }
}