如何获取 Android 设备的CPU核数、时钟频率以及内存大小

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。

YearCoresClockRAM20081528MHz192MB2009n/a600MHz290MB2010n/a1.0GHz512MB201121.2GHz1GB201241.5GHz1.5GB2013n/a2.0GHz2GB2014n/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 # lscpu0cpufreqcpuidlekernel_maxmodaliasofflineonlinepossiblepowerpresentuevent

统计一下文件个数便可以获得 CPU 核数。

<code class="language-java hljs  has-numbering" style="margin: 0px; padding: 0px;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">public <span class="hljs-keyword" style="margin: 0px; padding: 0px;">static <span class="hljs-keyword" style="margin: 0px; padding: 0px;">int <span class="hljs-title" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">getNumberOfCPUCores() {  <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.GINGERBREAD_MR1) {    <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">// Gingerbread doesn't support giving a single application access to both cores, but a    <span class="hljs-comment" style="margin: 0px; padding: 0px;">// handful of devices (Atrix 4G and Droid X2 for example) were released with a dual-core    <span class="hljs-comment" style="margin: 0px; padding: 0px;">// chipset and Gingerbread; that can let an app in the background run without impacting    <span class="hljs-comment" style="margin: 0px; padding: 0px;">// the foreground application. But for our purposes, it makes them single core.    <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">return <span class="hljs-number" style="margin: 0px; padding: 0px;">1;  }  <span class="hljs-keyword" style="margin: 0px; padding: 0px;">int cores;  <span class="hljs-keyword" style="margin: 0px; padding: 0px;">try {    cores = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new File(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"/sys/devices/system/cpu/").listFiles(CPU_FILTER).length;  } <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">catch (SecurityException e) {    cores = DEVICEINFO_UNKNOWN;  } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">catch (NullPointerException e) {    cores = DEVICEINFO_UNKNOWN;  }  <span class="hljs-keyword" style="margin: 0px; padding: 0px;">return cores;}<span class="hljs-keyword" style="margin: 0px; padding: 0px;">private <span class="hljs-keyword" style="margin: 0px; padding: 0px;">static <span class="hljs-keyword" style="margin: 0px; padding: 0px;">final FileFilter CPU_FILTER = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new FileFilter() {  <span class="hljs-annotation" style="margin: 0px; padding: 0px; color: green;">@Override  <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">public <span class="hljs-keyword" style="margin: 0px; padding: 0px;">boolean <span class="hljs-title" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">accept(File pathname) {    String path = pathname.getName();    <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">//regex is slow, so checking char by char.    <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">if (path.startsWith(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"cpu")) {      <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">for (<span class="hljs-keyword" style="margin: 0px; padding: 0px;">int i = <span class="hljs-number" style="margin: 0px; padding: 0px;">3; i < path.length(); i++) {        <span class="hljs-keyword" style="margin: 0px; padding: 0px;">if (path.charAt(i) < <span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">'0' || path.charAt(i) > <span class="hljs-string" style="margin: 0px; padding: 0px;">'9') {          <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">return <span class="hljs-keyword" style="margin: 0px; padding: 0px;">false;        }      }      <span class="hljs-keyword" style="margin: 0px; padding: 0px;">return <span class="hljs-keyword" style="margin: 0px; padding: 0px;">true;    }    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">return <span class="hljs-keyword" style="margin: 0px; padding: 0px;">false;  }};</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>

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   : 0vendor_id   : GenuineIntelcpu family  : 6model       : 70model name  : Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHzstepping    : 1cpu MHz     : 0.000cache size  : 1024 KBfdiv_bug    : nohlt_bug     : nof00f_bug    : nocoma_bug    : nofpu     : yesfpu_exception   : yescpuid level : 4wp      : yes

代码如下：

<code class="language-java hljs  has-numbering" style="margin: 0px; padding: 0px;"><span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">public <span class="hljs-keyword" style="margin: 0px; padding: 0px;">static <span class="hljs-keyword" style="margin: 0px; padding: 0px;">int <span class="hljs-title" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">getCPUMaxFreqKHz() {  <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">int maxFreq = DEVICEINFO_UNKNOWN;  <span class="hljs-keyword" style="margin: 0px; padding: 0px;">try {    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">for (<span class="hljs-keyword" style="margin: 0px; padding: 0px;">int i = <span class="hljs-number" style="margin: 0px; padding: 0px;">0; i < getNumberOfCPUCores(); i++) {      String filename =          <span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"/sys/devices/system/cpu/cpu" + i + <span class="hljs-string" style="margin: 0px; padding: 0px;">"/cpufreq/cpuinfo_max_freq";      File cpuInfoMaxFreqFile = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">new File(filename);      <span class="hljs-keyword" style="margin: 0px; padding: 0px;">if (cpuInfoMaxFreqFile.exists()) {        <span class="hljs-keyword" style="margin: 0px; padding: 0px;">byte[] buffer = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new <span class="hljs-keyword" style="margin: 0px; padding: 0px;">byte[<span class="hljs-number" style="margin: 0px; padding: 0px;">128];        FileInputStream stream = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new FileInputStream(cpuInfoMaxFreqFile);        <span class="hljs-keyword" style="margin: 0px; padding: 0px;">try {          stream.read(buffer);          <span class="hljs-keyword" style="margin: 0px; padding: 0px;">int endIndex = <span class="hljs-number" style="margin: 0px; padding: 0px;">0;          <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">//Trim the first number out of the byte buffer.          <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">while (buffer[endIndex] >= <span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">'0' && buffer[endIndex] <= <span class="hljs-string" style="margin: 0px; padding: 0px;">'9'              && endIndex < buffer.length) endIndex++;          String str = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">new String(buffer, <span class="hljs-number" style="margin: 0px; padding: 0px;">0, endIndex);          Integer freqBound = Integer.parseInt(str);          <span class="hljs-keyword" style="margin: 0px; padding: 0px;">if (freqBound > maxFreq) maxFreq = freqBound;        } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">catch (NumberFormatException e) {          <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">//Fall through and use /proc/cpuinfo.        } <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">finally {          stream.close();        }      }    }    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">if (maxFreq == DEVICEINFO_UNKNOWN) {      FileInputStream stream = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new FileInputStream(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"/proc/cpuinfo");      <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">try {        <span class="hljs-keyword" style="margin: 0px; padding: 0px;">int freqBound = parseFileForValue(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"cpu MHz", stream);        freqBound *= <span class="hljs-number" style="margin: 0px; padding: 0px;">1000; <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">//MHz -> kHz        <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">if (freqBound > maxFreq) maxFreq = freqBound;      } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">finally {        stream.close();      }    }  } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">catch (IOException e) {    maxFreq = DEVICEINFO_UNKNOWN; <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">//Fall through and return unknown.  }  <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">return maxFreq;}</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>

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。

<code class="language-java hljs  has-numbering" style="margin: 0px; padding: 0px;">ActivityManager.MemoryInfo memInfo = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">new ActivityManager.MemoryInfo();ActivityManager am = (ActivityManager) c.getSystemService(Context.ACTIVITY_SERVICE);am.getMemoryInfo(memInfo);</span></code>

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如果版本低于 JELLY_BEAN ，则只能读取系统文件了。

<code class="language-java hljs  has-numbering" style="margin: 0px; padding: 0px;">FileInputStream stream = <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">new FileInputStream(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"/proc/meminfo");totalMem = parseFileForValue(<span class="hljs-string" style="margin: 0px; padding: 0px;">"MemTotal", stream);</span></span></span></code>

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完整代码如下：

<code class="language-java hljs  has-numbering" style="margin: 0px; padding: 0px;"><span class="hljs-annotation" style="margin: 0px; padding: 0px; color: green;">@TargetApi(Build.VERSION_CODES.JELLY_BEAN)<span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">public <span class="hljs-keyword" style="margin: 0px; padding: 0px;">static <span class="hljs-keyword" style="margin: 0px; padding: 0px;">long <span class="hljs-title" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">getTotalMemory(Context c) {  <span class="hljs-comment" style="margin: 0px; padding: 0px; color: green;">// memInfo.totalMem not supported in pre-Jelly Bean APIs.  <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {    ActivityManager.MemoryInfo memInfo = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new ActivityManager.MemoryInfo();    ActivityManager am = (ActivityManager) c.getSystemService(Context.ACTIVITY_SERVICE);    am.getMemoryInfo(memInfo);    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">if (memInfo != <span class="hljs-keyword" style="margin: 0px; padding: 0px;">null) {      <span class="hljs-keyword" style="margin: 0px; padding: 0px;">return memInfo.totalMem;    } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">else {      <span class="hljs-keyword" style="margin: 0px; padding: 0px;">return DEVICEINFO_UNKNOWN;    }  } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">else {    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">long totalMem = DEVICEINFO_UNKNOWN;    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">try {      FileInputStream stream = <span class="hljs-keyword" style="margin: 0px; padding: 0px;">new FileInputStream(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"/proc/meminfo");      <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">try {        totalMem = parseFileForValue(<span class="hljs-string" style="margin: 0px; padding: 0px; color: rgb(163, 21, 21);">"MemTotal", stream);        totalMem *= <span class="hljs-number" style="margin: 0px; padding: 0px;">1024;      } <span class="hljs-keyword" style="margin: 0px; padding: 0px; color: rgb(0, 0, 255);">finally {        stream.close();      }    } <span class="hljs-keyword" style="margin: 0px; padding: 0px;">catch (IOException e) {    }    <span class="hljs-keyword" style="margin: 0px; padding: 0px;">return totalMem;  }}</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></code>