本文实例讲述了Android获取设备CPU核数、时钟频率以及内存大小的方法。分享给大家供大家参考，具体如下：

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 cpud+。

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; } }

希望本文所述对大家Android程序设计有所帮助。