C++ 获取特定进程的CPU使用率<转>

#include <Windows.h>
//原理：调用GetProcessTimes()，并与上次调用得到的结果相减，即得到某段时间内CPU的使用时间
//C++ 获取特定进程规定CPU使用率 原文：http://blog.csdn.net/liuqx97bb/article/details/52058657
class CPUusage {
private:
typedef long long int64_t;
typedef unsigned long long uint64_t;
HANDLE _hProcess;
int _processor; //cpu数量
int64_t _last_time; //上一次的时间
int64_t _last_system_time; // 时间转换
uint64_t file_time_2_utc(const FILETIME* ftime); // 获得CPU的核数
int get_processor_number(); //初始化
void init()
{
_last_system_time = ;
_last_time = ;
_hProcess = ;
} //关闭进程句柄
void clear()
{
if (_hProcess) {
CloseHandle(_hProcess);
_hProcess = ;
}
} public:
CPUusage(DWORD ProcessID) {
init();
_processor = get_processor_number();
setpid(ProcessID);
}
CPUusage() { init(); _processor = get_processor_number(); }
~CPUusage() { clear(); } //返回值为进程句柄，可判断OpenProcess是否成功
HANDLE setpid(DWORD ProcessID) {
clear(); //如果之前监视过另一个进程，就先关闭它的句柄
init();
return _hProcess= OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, false, ProcessID);
} //-1 即为失败或进程已退出； 如果成功，首次调用会返回-2（中途用setpid更改了PID后首次调用也会返回-2）
float get_cpu_usage();
};

float CPUusage::get_cpu_usage()
{ FILETIME now;
FILETIME creation_time;
FILETIME exit_time;
FILETIME kernel_time;
FILETIME user_time;
int64_t system_time;
int64_t time;
int64_t system_time_delta;
int64_t time_delta; DWORD exitcode; float cpu = -; if (!_hProcess) return -; GetSystemTimeAsFileTime(&now); //判断进程是否已经退出
GetExitCodeProcess(_hProcess, &exitcode);
if (exitcode != STILL_ACTIVE) {
clear();
return -;
} //计算占用CPU的百分比
if (!GetProcessTimes(_hProcess, &creation_time, &exit_time, &kernel_time, &user_time))
{
clear();
return -;
}
system_time = (file_time_2_utc(&kernel_time) + file_time_2_utc(&user_time))
/ _processor;
time = file_time_2_utc(&now); //判断是否为首次计算
if ((_last_system_time == ) || (_last_time == ))
{
_last_system_time = system_time;
_last_time = time;
return -;
} system_time_delta = system_time - _last_system_time;
time_delta = time - _last_time; if (time_delta == ) {
return -;
} cpu = (float)system_time_delta * / (float)time_delta;
_last_system_time = system_time;
_last_time = time;
return cpu;
} CPUusage::uint64_t CPUusage::file_time_2_utc(const FILETIME* ftime)
{
LARGE_INTEGER li; li.LowPart = ftime->dwLowDateTime;
li.HighPart = ftime->dwHighDateTime;
return li.QuadPart;
} int CPUusage::get_processor_number()
{
SYSTEM_INFO info;
GetSystemInfo(&info);
return info.dwNumberOfProcessors;
}

#include "CPUusage.h"
int _tmain(int argc, _TCHAR* argv[])
{ CPUusage usg();
for (int i = ; i < ; i++)
{
float cpu = usg.get_cpu_usage();
printf("Taskmgr.exe: %.2f%%\n", cpu);
Sleep();
} usg.setpid();
for (int i = ; i < ; i++)
{
float cpu = usg.get_cpu_usage();
printf("devenv.exe: %.2f%%\n", cpu);
Sleep();
} return ;
}