android获取RAM、CPU频率、系统版本、CPU核数

参考链接：
https://www.jianshu.com/p/76d68d13c475
https://github.com/matthewYang92/Themis

获取CPU频率、核数的逻辑，是通过文件操作实现的，Android是基于Linux系统的，所以该方式针对不同的手机都是可靠的操作方式。

RAM：

	public static final int DEVICEINFO_UNKNOWN = -1;/*** Calculates the total RAM of the device through Android API or /proc/meminfo.** @param c - Context object for current running activity.* @return Total RAM that the device has, or DEVICEINFO_UNKNOWN = -1 in the event of an error.*/@TargetApi(Build.VERSION_CODES.JELLY_BEAN)public static long getTotalMemory(Context c) {// 内存是按照1024计算int thundred = 1024;// 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 / (thundred * thundred);} else {return DEVICEINFO_UNKNOWN;}} else {// 低版本不做处理，因此默认返回0return DEVICEINFO_UNKNOWN;}}

CPU频率：

    /*** Method for reading the clock speed of a CPU core on the device. Will read from either* {@code /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq} or {@code /proc/cpuinfo}.** @return Clock speed of a core on the device, or -1 in the event of an error.*/public static ArrayList<Integer> getCPUFreqMHzs() {int maxFreq = DEVICEINFO_UNKNOWN;int curFreq = 0;ArrayList<Integer> arrayList = new ArrayList<Integer>();try {int coreNum = getNumberOfCPUCores();for (int i = 0; i < coreNum; i++) {String filename ="/sys/devices/system/cpu/cpu" + i + "/cpufreq/cpuinfo_max_freq";File cpuInfoMaxFreqFile = new File(filename);if (cpuInfoMaxFreqFile.exists() && cpuInfoMaxFreqFile.canRead()) {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 (Character.isDigit(buffer[endIndex]) && endIndex < buffer.length) {endIndex++;}String str = new String(buffer, 0, endIndex);// 频率是按照1000计算curFreq = Integer.parseInt(str) / 1000;arrayList.add(curFreq);} catch (NumberFormatException e) {} finally {stream.close();}}}if (maxFreq == DEVICEINFO_UNKNOWN && arrayList.size() == 0) {FileInputStream stream = new FileInputStream("/proc/cpuinfo");try {int freqBound = parseFileForValue("cpu MHz", stream);curFreq = freqBound;arrayList.add(curFreq);} finally {stream.close();}}} catch (IOException e) {}return arrayList;}/*** Reads the number of CPU cores from the first available information from* {@code /sys/devices/system/cpu/possible}, {@code /sys/devices/system/cpu/present},* then {@code /sys/devices/system/cpu/}.** @return Number of CPU cores in the phone, or DEVICEINFO_UKNOWN = -1 in the event of an error.*/public static int getNumberOfCPUCores() {if (coreNumber != DEVICEINFO_UNKNOWN) {return coreNumber;}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.coreNumber = 1;return coreNumber;}int cores;try {cores = getCoresFromFileInfo("/sys/devices/system/cpu/present");if (cores == DEVICEINFO_UNKNOWN) {cores = new File("/sys/devices/system/cpu/").listFiles(CPU_FILTER).length;;}} catch (SecurityException e) {cores = DEVICEINFO_UNKNOWN;} catch (NullPointerException e) {cores = DEVICEINFO_UNKNOWN;}coreNumber = cores;return coreNumber;}/*** Tries to read file contents from the file location to determine the number of cores on device.* @param fileLocation The location of the file with CPU information* @return Number of CPU cores in the phone, or DEVICEINFO_UKNOWN = -1 in the event of an error.*/private static int getCoresFromFileInfo(String fileLocation) {InputStream is = null;try {is = new FileInputStream(fileLocation);BufferedReader buf = new BufferedReader(new InputStreamReader(is));String fileContents = buf.readLine();buf.close();return getCoresFromFileString(fileContents);} catch (IOException e) {return DEVICEINFO_UNKNOWN;} finally {if (is != null) {try {is.close();} catch (IOException e) {// Do nothing.}}}}/*** Converts from a CPU core information format to number of cores.* @param str The CPU core information string, in the format of "0-N"* @return The number of cores represented by this string*/private static int getCoresFromFileString(String str) {if (str == null || !str.matches("0-[\\d]+$")) {return DEVICEINFO_UNKNOWN;}return Integer.valueOf(str.substring(2)) + 1;}private static final FileFilter CPU_FILTER = new FileFilter() {@Overridepublic 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 (!Character.isDigit(path.charAt(i))) {return false;}}return true;}return false;}};/*** Helper method for reading values from system files, using a minimised buffer.** @param textToMatch - Text in the system files to read for.* @param stream      - FileInputStream of the system file being read from.* @return A numerical value following textToMatch in specified the system file.* -1 in the event of a failure.*/private static int parseFileForValue(String textToMatch, FileInputStream stream) {byte[] buffer = new byte[1024];try {int length = stream.read(buffer);for (int i = 0; i < length; i++) {if (buffer[i] == '\n' || i == 0) {if (buffer[i] == '\n') i++;for (int j = i; j < length; j++) {int textIndex = j - i;//Text doesn't match query at some point.if (buffer[j] != textToMatch.charAt(textIndex)) {break;}//Text matches query here.if (textIndex == textToMatch.length() - 1) {return extractValue(buffer, j);}}}}} catch (IOException e) {//Ignore any exceptions and fall through to return unknown value.} catch (NumberFormatException e) {}return DEVICEINFO_UNKNOWN;}/*** Helper method used by {@link #parseFileForValue(String, FileInputStream) parseFileForValue}. Parses* the next available number after the match in the file being read and returns it as an integer.* @param index - The index in the buffer array to begin looking.* @return The next number on that line in the buffer, returned as an int. Returns* DEVICEINFO_UNKNOWN = -1 in the event that no more numbers exist on the same line.*/private static int extractValue(byte[] buffer, int index) {while (index < buffer.length && buffer[index] != '\n') {if (Character.isDigit(buffer[index])) {int start = index;index++;while (index < buffer.length && Character.isDigit(buffer[index])) {index++;}String str = new String(buffer, 0, start, index - start);return Integer.parseInt(str);}index++;}return DEVICEINFO_UNKNOWN;}

系统版本：

String systemVersion = android.os.Build.VERSION.RELEASE;

CPU核数：

    /*** Reads the number of CPU cores from the first available information from* {@code /sys/devices/system/cpu/possible}, {@code /sys/devices/system/cpu/present},* then {@code /sys/devices/system/cpu/}.** @return Number of CPU cores in the phone, or DEVICEINFO_UKNOWN = -1 in the event of an error.*/public static int getNumberOfCPUCores() {if (coreNumber != DEVICEINFO_UNKNOWN) {return coreNumber;}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.coreNumber = 1;return coreNumber;}int cores;try {cores = getCoresFromFileInfo("/sys/devices/system/cpu/present");if (cores == DEVICEINFO_UNKNOWN) {cores = new File("/sys/devices/system/cpu/").listFiles(CPU_FILTER).length;;}} catch (SecurityException e) {cores = DEVICEINFO_UNKNOWN;} catch (NullPointerException e) {cores = DEVICEINFO_UNKNOWN;}coreNumber = cores;return coreNumber;}