Android 限制后台進程數量/不保留活動

Android 限制后台進程數量/不保留活動

>> Don't keep activities

>> Background process limit

 

手動設置

進入系統設置 --> 打開開發者選項 --> 找到“不保留后台活動”/ “后台進程限制”-->按需設置

調用系統API設置

引入權限

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

 

調用設置

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) {
}

 

注意權限的問題，一般需要system app才可設置

 

查看設置信息

進到系統設置里，應該也可以看到UI已經按照設置變化了，或者使用命令查看

1. dumpsys activity settings 看如下值的變化

  mOverrideMaxCachedProcesses=4
  CUR_MAX_CACHED_PROCESSES=4

2. settings get global always_finish_activities

console:/ $ settings get global always_finish_activities
1

不保留活動還可以如下設置

settings put global always_finish_activities 1

import android.provider.Settings;

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

 

補充幾句

可以查看如下檔案：

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

里面的定義了默認最大可以緩存的進程數量

private static final int DEFAULT_MAX_CACHED_PROCESSES = 32;

 

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

ActivityManagerServic中提供了對外操作的方法，可以清楚看到，方法中首先去檢查權限

    @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);
        }
    }

 

參考

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