Android 清理后台进程，重要概念一网打尽

大家好，我是讯享网，很高兴认识大家。

源码解释: 让系统立即终止与给定程序包关联的所有后台进程。这与内核杀死那些进程以回收内存的过程相同。系统会在将来根据需要重新启动这些过程。

后台自动清理实现

通过自定义一个服务或者悬浮窗在后台运行,获取当前运行前台运行的包名,用一个集合recentList进行存储,当数量达到多少时执行清理任务

List recentList = new ArrayList<>(10); //后台包名缓存列表

执行桌面后台启动任务清理
@author lhw

private synchronized void clearRecentTask() {

Log.w(TAG, “clearRecnetTask recentList==” + recentList.toString());

final ActivityManager am = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);

long beforeMem = getAvailMemory(am);

Log.w(TAG, "-----------before memory info : " + beforeMem);

if (recentList != null && recentList.size() >= 5) {

TaskScheduler.ioHandler().post(new Runnable() {

@Override

public void run() {

int count = 0;

for (int i = 0; i < recentList.size() - 1; i++) {

if (!recentList.get(i).equals(“com.android.systemui”)) {

try {

am.killBackgroundProcesses(recentList.get(i));

recentList.remove(i);

Log.w(TAG, "It will be killed, package name : " + recentList.get(i));

} catch (Exception e) {

Log.e(TAG, "Exception clearMemory killBackgroundProcesses " + e.getMessage());

}

count++;

}

Log.w(TAG, "----------- after memory count : " + count);

}

});

}

long afterMem = getAvailMemory(am);

Log.w(TAG, "----------- after memory info : " + afterMem);

}

//获取可用内存大小

private long getAvailMemory(ActivityManager am) {

// 获取android当前可用内存大小

ActivityManager.MemoryInfo mi = new ActivityManager.MemoryInfo();

am.getMemoryInfo(mi);

Log.d(TAG, “可用内存---->>>” + mi.availMem / (1024 * 1024));

return mi.availMem / (1024 * 1024);

}

当前运行App包名获取方式
第一种通过定义一个辅助服务 AccessibilityService 中 AccessibilityEvent 的getPackageName 获取
第二种通过 UsageStatsManager获取当前运行包名,要跳转设置去申请android.permission.PACKAGE_USAGE_STATS权限

public static String getTopPackageName(Context context) {

String topActivityPackageName;

ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

final UsageStatsManager mUsageStatsManager = (UsageStatsManager) context.getSystemService(Service.USAGE_STATS_SERVICE);

long endTime = System.currentTimeMillis();

long beginTime = endTime - 60301000; // 1000 * 3;// * 60 * 2;

UsageEvents usageEvents = mUsageStatsManager.queryEvents(beginTime, endTime);

if (usageEvents == null || !usageEvents.hasNextEvent()) {

Log.w(“usageEvents==null”);

return null;

}

ComponentName comp = null;

String pkgName = null;

String clsName = null;

讯享网

UsageEvents.Event event = new UsageEvents.Event();

long prevTime = 0;

while(usageEvents.getNextEvent(event)) {

if (event.getEventType() == event.MOVE_TO_FOREGROUND) {

if (prevTime == 0 || Long.compare(event.getTimeStamp(), prevTime) > 0) {

pkgName = event.getPackageName();

clsName = event.getClassName();

prevTime = event.getTimeStamp();

}

} else if(event.getEventType() == event.MOVE_TO_BACKGROUND && prevTime != 0) {

pkgName = null;

clsName = null;

}

return pkgName;

} else {

List<ActivityManager.RunningTaskInfo> taskInfos = manager.getRunningTasks(1);

if (taskInfos.size() > 0)

topActivityPackageName = taskInfos.get(0).topActivity.getPackageName();

else

return null;

return topActivityPackageName;

}

forceStopPackage

次方法是系统隐藏的,而且还需要 android.Manifest.permission#FORCE_STOP_PACKAGES 权限

Have the system perform a force stop of everything associated with
the given application package. All processes that share its uid
will be killed, all services it has running stopped, all activities
removed, etc. In addition, a {@link Intent#ACTION_PACKAGE_RESTARTED}
broadcast will be sent, so that any of its registered alarms can
be stopped, notifications removed, etc.
You must hold the permission
{@link android.Manifest.permission#FORCE_STOP_PACKAGES} to be able to
call this method.
@param packageName The name of the package to be stopped.
@param userId The user for which the running package is to be stopped.
@hide This is not available to third party applications due to
it allowing them to break other applications by stopping their
services, removing their alarms, etc.
自我介绍一下，小编13年上海交大毕业，曾经在小公司待过，也去过华为、OPPO等大厂，18年进入阿里一直到现在。