Android 限制后台进程数量/不保留活动

>> Don't keep activities

>> Background process limit

手动设置

进入系统设置 --> 打开开发者选项 --> 找到“不保留后台活动”/ “后台进程限制”-->按需设置

调用系统API设置

引入权限

调用设置

import android.app.ActivityManager;
import android.app.IActivityManager;
import android.os.RemoteException;

try {
    IActivityManager am = ActivityManager.getService();
    am.setProcessLimit(0);
    am.setAlwaysFinish(true);
} catch (SecurityException e) {
} catch (RemoteException e) {
}

注意权限的问题，一般需要system app才可设置

查看设置信息

进到系统设置里，应该也可以看到UI已经按照设置变化了，或者使用命令查看

1. dumpsys activity settings 看如下值的变化

  mOverrideMaxCachedProcesses=4
  CUR_MAX_CACHED_PROCESSES=4

2. settings get global always_finish_activities

console:/ $ settings get global always_finish_activities
1

不保留活动还可以如下设置

settings put global always_finish_activities 1

import android.provider.Settings;

Settings.Global.putInt(this.getContentResolver(), Settings.Global.ALWAYS_FINISH_ACTIVITIES, 1);

补充几句

可以查看如下档案：

/frameworks/base/services/core/java/com/android/server/am/ActivityManagerConstants.java

里面的定义了默认最大可以缓存的进程数量

private static final int DEFAULT_MAX_CACHED_PROCESSES = 32;

/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

ActivityManagerServic中提供了对外操作的方法，可以清楚看到，方法中首先去检查权限

    @Override
    public void setProcessLimit(int max) {
        enforceCallingPermission(android.Manifest.permission.SET_PROCESS_LIMIT,
                "setProcessLimit()");
        synchronized (this) {
            mConstants.setOverrideMaxCachedProcesses(max);
        }
        trimApplications(OomAdjuster.OOM_ADJ_REASON_PROCESS_END);
    }



    @Override
    public void setAlwaysFinish(boolean enabled) {
        enforceCallingPermission(android.Manifest.permission.SET_ALWAYS_FINISH,
                "setAlwaysFinish()");

        long ident = Binder.clearCallingIdentity();
        try {
            Settings.Global.putInt(
                    mContext.getContentResolver(),
                    Settings.Global.ALWAYS_FINISH_ACTIVITIES, enabled ? 1 : 0);

            synchronized (this) {
                mAlwaysFinishActivities = enabled;
            }
        } finally {
            Binder.restoreCallingIdentity(ident);
        }
    }

参考

https://blog.csdn.net/qq_34694875/article/details/103906890

AndroidPrograming Android开发技术

Android 限制后台进程数量/不保留活动