写在前面：
进入手机ODM已经很久，经历过几个项目项目下来，对高通、展讯、Marvell平台都进行了接触，对于我个人来说，参与手机系统项目的开发与维护，最明显的好处是可以深入的了解某一功能的具体实现过程，以及Android的设计框架，能够以框架的思维去修改代码添加功能。入行这么久，越来越觉得有必要将自己在实际工作过程中看到的，领悟到的一些东西能够记忆下来，并分享出来。
从这篇开始我将会筛选出一些常用功能在Google源码中的标准方法与大家一起分享，对于我个人来讲，比较喜欢按照源码中已经存在了的标准方法去coding。
首先共享的是 杀死进程的方法， 一般手机管家类应用最基本的就是清理进程的功能。其实这个功能在源码里面来看是很简单的，主要有两步骤：1.获取正在运行的进程列表；2.根据packageName选择怎样去杀掉。
2015.05.06 更新一种方法，利用反射机制调用ActivityManagerService::forceStopPackage来杀掉进程（适用于usr组，但仍然不一定成功）。
这部分的功能主要参考了
1. 设置--应用--正在运行--停止所有进程
2. 任意界面--长按Home--清理最近进程
设置中获取所用应用程序的做法：
主要使用PackageManager::getInstalledApplications(int flags){} 方法
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final int mRetrieveFlags;
List<ApplicationInfo> mApplications = new ArrayList<ApplicationInfo>();
// Only the owner can see all apps.
if (UserHandle.myUserId() == 0) {
mRetrieveFlags = PackageManager.GET_UNINSTALLED_PACKAGES |
PackageManager.GET_DISABLED_COMPONENTS |
PackageManager.GET_DISABLED_UNTIL_USED_COMPONENTS;
} else {
mRetrieveFlags = PackageManager.GET_DISABLED_COMPONENTS |
PackageManager.GET_DISABLED_UNTIL_USED_COMPONENTS;
}
// 获取系统中的所有包
<strong>mApplications = mPm.getInstalledApplications(mRetrieveFlags);</strong>
if (mApplications == null) {
mApplications = new ArrayList<ApplicationInfo>();
}
for (int i=0; i<mApplications.size(); i++) {
final ApplicationInfo info = mApplications.get(i);
// Need to trim out any applications that are disabled by
// something different than the user.
if (!info.enabled) { //此处很有必要，获取未被禁止的且允许被操作的包
if (info.enabledSetting != PackageManager.COMPONENT_ENABLED_STATE_DISABLED_USER) {
mApplications.remove(i);
i--;
continue;
}
mHaveDisabledApps = true;
}
}
标准方法获取正在运行的进程：
主要使用ActivityManagerService::getRunningAppProcesses(){} 方法
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// Temporary structure used when updating above information.
final SparseArray<AppProcessInfo> mTmpAppProcesses = new SparseArray<AppProcessInfo>();
// Retrieve list of running processes, organizing them into a sparse
// array for easy retrieval.
List<ActivityManager.RunningAppProcessInfo> processes
= am.getRunningAppProcesses(); // 获取正在运行的进程
final int NP = processes != null ? processes.size() : 0;
mTmpAppProcesses.clear();
for (int i=0; i<NP; i++) {
ActivityManager.RunningAppProcessInfo pi = processes.get(i);
mTmpAppProcesses.put(pi.pid, new AppProcessInfo(pi));
}
杀死正在运行进程的方法：
适合api LEVEL <= 7
权限 android.permission.RESTART_PACKAGE
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private void killPackage(String pkgName) {
ActivityManager am = (ActivityManager)getActivity().getSystemService(
Context.ACTIVITY_SERVICE);
am.restartPackage(pkgName);
}
适合api LEVEL >=8
权限 android.permission.KILL_BACKGORUND_PROCESSES
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private void killPackage(String pkgName) {
ActivityManager am = (ActivityManager)getActivity().getSystemService(
Context.ACTIVITY_SERVICE);
am.killBackgroundProcesses(pkgName);
}
设置--应用--详细--强制停止：
对于非System组进程，无法调用ActivityManager::forceStopPackage(String){}方法，只能尝试使用ActivityManagerService::forceStopPackage(final String packageName, int userId) 并且不一定能成功，设置中的逻辑大致如下：
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private DevicePolicyManager mDpm = (DevicePolicyManager)getActivity().getSystemService(Context.DEVICE_POLICY_SERVICE);
private final BroadcastReceiver mCheckKillProcessesReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
updateForceStopButton(getResultCode() != Activity.RESULT_CANCELED);
}
};
private void updateForceStopButton(boolean enabled) {
mForceStopButton.setEnabled(enabled);
mForceStopButton.setOnClickListener(InstalledAppDetails.this);
}
private void checkForceStop() {
if (mDpm.packageHasActiveAdmins(mPackageInfo.packageName)) {
// User can't force stop device admin.
updateForceStopButton(false);
} else if ((mAppEntry.info.flags&ApplicationInfo.FLAG_STOPPED) == 0) {
// If the app isn't explicitly stopped, then always show the
// force stop button.
updateForceStopButton(true);
} else {
Intent intent = new Intent(Intent.ACTION_QUERY_PACKAGE_RESTART,
Uri.fromParts("package", mAppEntry.info.packageName, null));
intent.putExtra(Intent.EXTRA_PACKAGES, new String[] { mAppEntry.info.packageName });
intent.putExtra(Intent.EXTRA_UID, mAppEntry.info.uid);
intent.putExtra(Intent.EXTRA_USER_HANDLE, UserHandle.getUserId(mAppEntry.info.uid));
getActivity().sendOrderedBroadcastAsUser(intent, UserHandle.CURRENT, null,
mCheckKillProcessesReceiver, null, Activity.RESULT_CANCELED, null, null);
}
}
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private void forceStopPackage(String pkgName) {
ActivityManager am = (ActivityManager)getActivity().getSystemService(
Context.ACTIVITY_SERVICE);
am.forceStopPackage(pkgName); // 不一定成功
mState.invalidatePackage(pkgName); // 强制停止后重新获取一下包信息
ApplicationsState.AppEntry newEnt = mState.getEntry(pkgName);
if (newEnt != null) {
mAppEntry = newEnt;
}
checkForceStop(); // 最后检验是否强停成功（体现在“强行停止”按钮是否置灰）
}
在调试过程中，强行停止某一进程的方法是：
adb shell am force-stop <package>
比如： am force-stop com.android.launcher
另外 am kill <package> 安全模式下杀死进程，不影响体验
附：
am force-stop: force stop everything associated with <PACKAGE>.
--user <USER_ID> | all | current: Specify user to force stop;
all users if not specified.
am kill: Kill all processes associated with <PACKAGE>. Only kills.
processes that are safe to kill -- that is, will not impact the user
experience.
--user <USER_ID> | all | current: Specify user whose processes to kill;
all users if not specified.
am kill-all: Kill all background processes.
第三种方法：
通过反射机制，杀死进程
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package com.example.androidtest;
import android.app.ActivityManager;
import android.content.Context;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* 通过Java的反射机制强制杀死进程
* @author hanhao
*
*/
public class ForceKillProgress {
public static void forceStopProgress(Context context, String pkgName) {
ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
try {
Method forceStopPackage = am.getClass().getDeclaredMethod("forceStopPackage", String.class);
forceStopPackage.setAccessible(true);
forceStopPackage.invoke(am, pkgName);
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
}
