如何获取 Android 设备的CPU核数时钟频率以及内存大小
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因项目需要,分析了一下 Facebook 的开源项目 - Device Year Class。
Device Year Class 的主要功能是根据 CPU核数、时钟频率 以及 内存大小 对设备进行分级。代码很简单,只包含两个类:
DeviceInfo
-> 获取设备参数,YearClass
-> 根据参数进行分级。
下表是 Facebook 公司提供的分级标准,其中 Year
栏表示分级结果。
Year | Cores | Clock | RAM |
---|---|---|---|
2008 | 1 | 528MHz | 192MB |
2009 | n/a | 600MHz | 290MB |
2010 | n/a | 1.0GHz | 512MB |
2011 | 2 | 1.2GHz | 1GB |
2012 | 4 | 1.5GHz | 1.5GB |
2013 | n/a | 2.0GHz | 2GB |
2014 | n/a | >2GHz | >2GB |
关于输出年份的计算方法可以参考源码,本文只把一些比较常用的功能抽取出来做一个简要介绍。
获取 CPU 核数
我们都知道,Linux 中的设备都是以文件的形式存在,CPU 也不例外,因此 CPU 的文件个数就等价与核数。
android 的 CPU 设备文件位于 /sys/devices/system/cpu/
目录,文件名的的格式为 cpu\\d+
。
root@generic_x86_64:/sys/devices/system/cpu # ls cpu0 cpufreq cpuidle kernel_max modalias offline online possible power present uevent
统计一下文件个数便可以获得 CPU 核数。
public static int getNumberOfCPUCores()
if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.GINGERBREAD_MR1)
// Gingerbread doesn't support giving a single application access to both cores, but a
// handful of devices (Atrix 4G and Droid X2 for example) were released with a dual-core
// chipset and Gingerbread; that can let an app in the background run without impacting
// the foreground application. But for our purposes, it makes them single core.
return 1;
int cores;
try
cores = new File("/sys/devices/system/cpu/").listFiles(CPU_FILTER).length;
catch (SecurityException e)
cores = DEVICEINFO_UNKNOWN;
catch (NullPointerException e)
cores = DEVICEINFO_UNKNOWN;
return cores;
private static final FileFilter CPU_FILTER = new FileFilter()
@Override
public boolean accept(File pathname)
String path = pathname.getName();
//regex is slow, so checking char by char.
if (path.startsWith("cpu"))
for (int i = 3; i < path.length(); i++)
if (path.charAt(i) < '0' || path.charAt(i) > '9')
return false;
return true;
return false;
;
获取时钟频率
获取时钟频率需要读取系统文件 - /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
或者 /proc/cpuinfo
。
我的 Android 模拟器中并没有 cpuinfo_max_freq
文件,因此只能读取 /proc/cpuinfo
。
/proc/cpuinfo
包含了很多 cpu 数据。
processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 70 model name : Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz stepping : 1 cpu MHz : 0.000 cache size : 1024 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 4 wp : yes
代码如下:
public static int getCPUMaxFreqKHz()
int maxFreq = DEVICEINFO_UNKNOWN;
try
for (int i = 0; i < getNumberOfCPUCores(); i++)
String filename =
"/sys/devices/system/cpu/cpu" + i + "/cpufreq/cpuinfo_max_freq";
File cpuInfoMaxFreqFile = new File(filename);
if (cpuInfoMaxFreqFile.exists())
byte[] buffer = new byte[128];
FileInputStream stream = new FileInputStream(cpuInfoMaxFreqFile);
try
stream.read(buffer);
int endIndex = 0;
//Trim the first number out of the byte buffer.
while (buffer[endIndex] >= '0' && buffer[endIndex] <= '9'
&& endIndex < buffer.length) endIndex++;
String str = new String(buffer, 0, endIndex);
Integer freqBound = Integer.parseInt(str);
if (freqBound > maxFreq) maxFreq = freqBound;
catch (NumberFormatException e)
//Fall through and use /proc/cpuinfo.
finally
stream.close();
if (maxFreq == DEVICEINFO_UNKNOWN)
FileInputStream stream = new FileInputStream("/proc/cpuinfo");
try
int freqBound = parseFileForValue("cpu MHz", stream);
freqBound *= 1000; //MHz -> kHz
if (freqBound > maxFreq) maxFreq = freqBound;
finally
stream.close();
catch (IOException e)
maxFreq = DEVICEINFO_UNKNOWN; //Fall through and return unknown.
return maxFreq;
获取内存大小
如果 SDK 版本大于等于 JELLY_BEAN
,可以通过 ActivityManager
来获取内从大小。
ActivityManager.MemoryInfo memInfo = new ActivityManager.MemoryInfo();
ActivityManager am = (ActivityManager) c.getSystemService(Context.ACTIVITY_SERVICE);
am.getMemoryInfo(memInfo);
如果版本低于 JELLY_BEAN
,则只能读取系统文件了。
FileInputStream stream = new FileInputStream("/proc/meminfo");
totalMem = parseFileForValue("MemTotal", stream);
完整代码如下:
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
public static long getTotalMemory(Context c)
// memInfo.totalMem not supported in pre-Jelly Bean APIs.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
ActivityManager.MemoryInfo memInfo = new ActivityManager.MemoryInfo();
ActivityManager am = (ActivityManager) c.getSystemService(Context.ACTIVITY_SERVICE);
am.getMemoryInfo(memInfo);
if (memInfo != null)
return memInfo.totalMem;
else
return DEVICEINFO_UNKNOWN;
else
long totalMem = DEVICEINFO_UNKNOWN;
try
FileInputStream stream = new FileInputStream("/proc/meminfo");
try
totalMem = parseFileForValue("MemTotal", stream);
totalMem *= 1024;
finally
stream.close();
catch (IOException e)
return totalMem;
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如何获取 Android 设备的CPU核数时钟频率以及内存大小