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最近在优化 App 的性能，需要获取当前 CPU视频频率和占用率，通过查询资料，大致思路如下：

目前没有标准的 API 来获取 CPU 的使用频率，只能通过读取指定 CPU 文件获取当前 CPU 频率，在某些机器或者特定版本中，可能需要ROOT 权限或者特殊权限，因此会存在一定几率的失败，因此需要做好 Try…catch 动作。又因为现在手机 CPU 的多核数目，因此我们可能需要获取多个 CPU 频率数，并取平均值。

获取系统 CPU 核心数：

 val cpuCoreNum = Runtime.getRuntime().availableProcessors()

获取指定 CPU 当前频率：

/sys/devices/system/cpu/cpu${index}/cpufreq/scaling_cur_freq

那么核心代码为：

private fun getAllCpuCoreFrequency() : Long {var frequency = 0Lfor (index in 0 until  cpuCoreNum){frequency += readFile("/sys/devices/system/cpu/cpu$index/cpufreq/scaling_cur_freq")}BLog.d("frequency : $frequency")return frequency / cpuCoreNum}private fun readFile(filePath: String): Long{try {val file = RandomAccessFile(filePath, "r")val content = file.readLine()file.close()if (TextUtils.isEmpty(content)){return 0L}BLog.d("readFile content : $content")return content.trim().toLong()}catch (e : Exception){e.printStackTrace()return 0L}}

如果需要获取 CPU 的占用率，那么就需要知道每个核心的最大频率和最小频率，同样是通过文件获取：

//max frequency file
/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_max_freq//min frequency file
/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_min_freq

那么核心代码为：

object CPUUtils {private var cpuCoreNum = 0private var cpuMaxFrequency = 0Lprivate var cpuMinFrequency = 0Lfun initCpuCoreNum(){if (cpuCoreNum <= 0 || cpuMaxFrequency <= 0L || cpuMinFrequency <= 0L){cpuCoreNum = Runtime.getRuntime().availableProcessors()initMaxAndMinFrequency()if (cpuCoreNum > 0 && cpuMaxFrequency > 0L && cpuMinFrequency > 0L){SpManager.getInstance().setCanUseCPUFrequency(true)}}BLog.d("cpuCoreNum : $cpuCoreNum")}private fun initMaxAndMinFrequency()  {if (cpuCoreNum <= 0){return}cpuMaxFrequency = 0LcpuMinFrequency = 0Lfor (index in 0 until cpuCoreNum){cpuMaxFrequency += readFile("/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_max_freq")cpuMinFrequency += readFile("/sys/devices/system/cpu/cpu${index}/cpufreq/cpuinfo_min_freq")}BLog.d("cpuMaxFrequency : $cpuMaxFrequency, cpuMinFrequency : $cpuMinFrequency")}private fun readFile(filePath: String): Long{try {val file = RandomAccessFile(filePath, "r")val content = file.readLine()file.close()if (TextUtils.isEmpty(content)){return 0L}BLog.d("readFile content : $content")return content.trim().toLong()}catch (e : Exception){ExceptionHandler.recordException(e)return 0L}}private fun getAllCpuCoreFrequency() : Long {initCpuCoreNum()if (cpuCoreNum <=0){return 0L}var frequency = 0Lfor (index in 0 until  cpuCoreNum){frequency += readFile("/sys/devices/system/cpu/cpu$index/cpufreq/scaling_cur_freq")}BLog.d("frequency : $frequency")return frequency}fun findCurrentFrequencyPercent() : Long {val currentFrequency = getAllCpuCoreFrequency()BLog.d("currentFrequency : $currentFrequency, cpuMinFrequency : $cpuMinFrequency, cpuMaxFrequency : $cpuMaxFrequency")if (cpuMaxFrequency - cpuMinFrequency <= 0L || currentFrequency - cpuMinFrequency < 0L || cpuMaxFrequency - currentFrequency < 0L){return 0L}return (currentFrequency - cpuMinFrequency) * 100 / (cpuMaxFrequency - cpuMinFrequency)}fun getCpuCoreFrequency() : Long {initCpuCoreNum()if (cpuCoreNum <=0){return 0L}return getAllCpuCoreFrequency() / cpuCoreNum}}

获取 CPU 频率：

CPUUtils.getCpuCoreFrequency()

获取 CPU 占用率：

CPUtils.findCurrentFrequencyPercent()