
360桌面、金山清理大師等都提供了一鍵清理、一鍵加速等功能,其實就是殺一些後台進程來達到釋放內存的目的。
基本思路就是列出所有運行的進程,查看其重要值(RunningAppProcessInfo.importance,值越大說明進程重要程度越低),可以設定一個閾值,
如果該進程的重要值大於該閾值,就可以殺掉該進程。
進程的重要值有以下幾個等級:
/**
* Constant for {@link #importance}: this is a persistent process.
* Only used when reporting to process observers.
* @hide
*/
public static final int IMPORTANCE_PERSISTENT = 50;
/**
* Constant for {@link #importance}: this process is running the
* foreground UI.
*/
public static final int IMPORTANCE_FOREGROUND = 100;
/**
* Constant for {@link #importance}: this process is running something
* that is actively visible to the user, though not in the immediate
* foreground.
*/
public static final int IMPORTANCE_VISIBLE = 200;
/**
* Constant for {@link #importance}: this process is running something
* that is considered to be actively perceptible to the user. An
* example would be an application performing background music playback.
*/
public static final int IMPORTANCE_PERCEPTIBLE = 130;
/**
* Constant for {@link #importance}: this process is running an
* application that can not save its state, and thus can't be killed
* while in the background.
* @hide
*/
public static final int IMPORTANCE_CANT_SAVE_STATE = 170;
/**
* Constant for {@link #importance}: this process is contains services
* that should remain running.
*/
public static final int IMPORTANCE_SERVICE = 300;
/**
* Constant for {@link #importance}: this process process contains
* background code that is expendable.
*/
public static final int IMPORTANCE_BACKGROUND = 400;
/**
* Constant for {@link #importance}: this process is empty of any
* actively running code.
*/
public static final int IMPORTANCE_EMPTY = 500;
直接上代碼:
package com.android.clearmemory;
import android.app.Activity;
import android.app.ActivityManager;
import android.app.ActivityManager.MemoryInfo;
import android.app.ActivityManager.RunningAppProcessInfo;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.util.List;
public class ClearMemoryActivity extends Activity {
private static final String TAG = “ClearMemoryActivity”;
/**
* Called when the activity is first created.
*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button clear = (Button) findViewById(R.id.clear);
clear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//To change body of implemented methods use File | Settings | File Templates.
ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
List<RunningAppProcessInfo> infoList = am.getRunningAppProcesses();
List<ActivityManager.RunningServiceInfo> serviceInfos = am.getRunningServices(100);
long beforeMem = getAvailMemory(ClearMemoryActivity.this);
Log.d(TAG, "-----------before memory info : " + beforeMem);
int count = 0;
if (infoList != null) {
for (int i = 0; i < infoList.size(); ++i) {
RunningAppProcessInfo appProcessInfo = infoList.get(i);
Log.d(TAG, "process name : " + appProcessInfo.processName);
//importance 該進程的重要程度 分為幾個級別,數值越低就越重要。
Log.d(TAG, "importance : " + appProcessInfo.importance);
// 一般數值大於RunningAppProcessInfo.IMPORTANCE_SERVICE的進程都長時間沒用或者空進程了
// 一般數值大於RunningAppProcessInfo.IMPORTANCE_VISIBLE的進程都是非可見進程,也就是在後台運行著
if (appProcessInfo.importance > RunningAppProcessInfo.IMPORTANCE_VISIBLE) {
String[] pkgList = appProcessInfo.pkgList;
for (int j = 0; j < pkgList.length; ++j) {//pkgList 得到該進程下運行的包名
Log.d(TAG, "It will be killed, package name : " + pkgList[j]);
am.killBackgroundProcesses(pkgList[j]);
count++;
}
}
}
}
long afterMem = getAvailMemory(ClearMemoryActivity.this);
Log.d(TAG, "----------- after memory info : " + afterMem);
Toast.makeText(ClearMemoryActivity.this, "clear " + count + " process, "
+ (afterMem - beforeMem) + "M", Toast.LENGTH_LONG).show();
}
});
ClearMemoryFloatView.instance(getApplicationContext()).createView();
}
//獲取可用內存大小
private long getAvailMemory(Context context) {
// 獲取android當前可用內存大小
ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
MemoryInfo mi = new MemoryInfo();
am.getMemoryInfo(mi);
//mi.availMem; 當前系統的可用內存
//return Formatter.formatFileSize(context, mi.availMem);// 將獲取的內存大小規格化
Log.d(TAG, "可用內存---->>>" + mi.availMem / (1024 * 1024));
return mi.availMem / (1024 * 1024);
}
}
作者:依然綠茶
來源:CSDN
原文:https://blog.csdn.net/whu_zhangmin/article/details/19123283
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