java获得CPU使用率
java获得CPU使用率,系统内存,虚拟机内存等情况(不用JNI)
2009年10月23日 星期五 16:30
在Java中，可以获得总的物理内存、剩余的物理内存、已使用的物理内存等信息，下面例子可以取得这些信息，并且获得在Windows下的内存使用率。
    首先编写一个MonitorInfoBean类，用来装载监控的一些信息，包括物理内存、剩余的物理内存、已使用的物理内存、内存使用率等字段，该类的代码如下：
package com.itor;
public class MonitorInfoBean {
/** 可使用内存. */
private long totalMemory;
/** 剩余内存. */
private long freeMemory;
/** 最大可使用内存. */
private long maxMemory;
/** 操作系统. */
private String osName;
/** 总的物理内存. */
private long totalMemorySize;
/** 剩余的物理内存. */
private long freePhysicalMemorySize;
/** 已使用的物理内存. */
private long usedMemory;
/** 线程总数. */
private int totalThread;
/** cpu使用率. */
private double cpuRatio;
public long getFreeMemory() {
  return freeMemory;
}
public void setFreeMemory(long freeMemory) {
  this.freeMemory = freeMemory;
}
public long getFreePhysicalMemorySize() {
  return freePhysicalMemorySize;
}
public void setFreePhysicalMemorySize(long freePhysicalMemorySize) {
  this.freePhysicalMemorySize = freePhysicalMemorySize;
}
public long getMaxMemory() {
  return maxMemory;
}
public void setMaxMemory(long maxMemory) {
  this.maxMemory = maxMemory;
}
public String getOsName() {
  return osName;
}
public void setOsName(String osName) {
  this.osName = osName;
}
public long getTotalMemory() {
  return totalMemory;
}
public void setTotalMemory(long totalMemory) {
  alMemory = totalMemory;
}
public long getTotalMemorySize() {
  return totalMemorySize;
}
public void setTotalMemorySize(long totalMemorySize) {
  alMemorySize = totalMemorySize;
}
public int getTotalThread() {
  return totalThread;
}
public void setTotalThread(int totalThread) {
  alThread = totalThread;
}
public long getUsedMemory() {
  return usedMemory;
}
public void setUsedMemory(long usedMemory) {
  this.usedMemory = usedMemory;
}
public double getCpuRatio() {
  return cpuRatio;
}
public void setCpuRatio(double cpuRatio) {
  this.cpuRatio = cpuRatio;
}
}
接着编写一个获得当前的监控信息的接口，该类的代码如下所示：
package com.itor;
/**
* 获取系统信息的业务逻辑类接口.
*/
枣庄市中考成绩查询public interface IMonitorService {
/**
  * 获得当前的监控对象.
  * @return 返回构造好的监控对象
  * @throws Exception
  */
public MonitorInfoBean getMonitorInfoBean() throws Exception;
}
该类的实现类MonitorServiceImpl如下所示：
package com.itor;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.util.StringTokenizer;
import sun.management.ManagementFactory;
import com.sun.management.OperatingSystemMXBean;
/**
*
* 获取系统信息的业务逻辑实现类.
*
* @author GuoHuang
*/
public class MonitorServiceImpl implements IMonitorService {
private static final int CPUTIME = 30;
快乐大本营20100501 private static final int PERCENT = 100;
private static final int FAULTLENGTH = 10;
private static String linuxVersion = null;
/**
  * 获得当前的监控对象.
  *
  * @return 返回构造好的监控对象
  * @throws Exception
  * @author GuoHuang
  */
public MonitorInfoBean getMonitorInfoBean() throws Exception {
  int kb = 1024;
  // 可使用内存
  long totalMemory = Runtime().totalMemory() / kb;
  // 剩余内存
  long freeMemory = Runtime().freeMemory() / kb;
  // 最大可使用内存
  long maxMemory = Runtime().maxMemory() / kb;
  OperatingSystemMXBean osmxb = (OperatingSystemMXBean) OperatingSystemMXBean();
  // 操作系统
  String osName = Property("os.name");
  // 总的物理内存
  long totalMemorySize = TotalPhysicalMemorySize() / kb;
  // 剩余的物理内存
  long freePhysicalMemorySize = FreePhysicalMemorySize() / kb;
  // 已使用的物理内存
  long usedMemory = (TotalPhysicalMemorySize() - FreePhysicalMemorySize()) / kb;
  // 获得线程总数
  ThreadGroup parentThread;
  for (parentThread = Thread.currentThread().getThreadGroup(); Parent() != null; parentThread = Parent());
  int totalThread = parentThread.activeCount();
  double cpuRatio = 0;
  if (LowerCase().startsWith("windows")) {
  cpuRatio = CpuRatioForWindows();
  } else {原神角推荐
  cpuRatio = getCpuRateForLinux();
  }
  // 构造返回对象
  MonitorInfoBean infoBean = new MonitorInfoBean();
  infoBean.setFreeMemory(freeMemory);
  infoBean.setFreePhysicalMemorySize(freePhysicalMemorySize);
  infoBean.setMaxMemory(maxMemory);
  infoBean.setOsName(osName);
  infoBean.setTotalMemory(totalMemory);
  infoBean.setTotalMemorySize(totalMemorySize);
  infoBean.setTotalThread(totalThread);
  infoBean.setUsedMemory(usedMemory);
  infoBean.setCpuRatio(cpuRatio);
  return infoBean;
}
private static double getCpuRateForLinux() {
  InputStream is = null;
  InputStreamReader isr = null;
  BufferedReader brStat = null;
  StringTokenizer tokenStat = null;
  try {
  System.out.println("Get usage rate of CUP , linux version: " + linuxVersion);
  Process process = Runtime().exec("top -b -n 1");
  is = InputStream();
  isr = new InputStreamReader(is);
  brStat = new BufferedReader(isr);
  if (linuxVersion.equals("2.4")) {
    adLine();
    adLine();
    adLine();
    adLine();
    tokenStat = new adLine());
    Token();
    Token();
    String user = Token();
    Token();
    String system = Token();
    Token();
    String nice = Token();
    System.out.println(user + " , " + system + " , " + nice);
    user = user.substring(0, user.indexOf("%"));
    system = system.substring(0, system.indexOf("%"));
    nice = nice.substring(0, nice.indexOf("%"));
    float userUsage = new Float(user).floatValue();
    float systemUsage = new Float(system).floatValue();
    float niceUsage = new Float(nice).floatValue();
    return (userUsage + systemUsage + niceUsage) / 100;
  } else {
    adLine();
    adLine();
    tokenStat = new adLine());
    Token();
    Token();
    Token();
    Token();
    Token();
    Token();
    Token();
    String cpuUsage = Token();
    System.out.println("CPU idle : " + cpuUsage);
    Float usage = new Float(cpuUsage.substring(0, cpuUsage.indexOf("%")));
    return (1 - usage.floatValue() / 100);
  }
  } catch (IOException ioe) {
  System.out.Message());
  freeResource(is, isr, brStat);
  return 1;
  } finally {
  freeResource(is, isr, brStat);
  }
}
private static void freeResource(InputStream is, InputStreamReader isr,
  BufferedReader br) {
  try {
  if (is != null)
    is.close();
  if (isr != null)
几号入伏2020几号入伏
    isr.close();
  if (br != null)
    br.close();
  } catch (IOException ioe) {
  System.out.Message());
  }
}
/**
  * 获得CPU使用率.
  *
  * @return 返回cpu使用率
  * @author GuoHuang
  */
private double getCpuRatioForWindows() {
  try {
  String procCmd = v("windir") + "\\system32\\wbem\\ process get Caption,CommandLine,KernelModeTime,ReadOperationCount,ThreadCount,UserModeTime,WriteOperationCount";
  // 取进程信息
  long[] c0 = Runtime().exec(procCmd));
  Thread.sleep(CPUTIME);
  long[] c1 = Runtime().exec(procCmd));
  if (c0 != null && c1 != null) {
    long idletime = c1[0] - c0[0];
    long busytime = c1[1] - c0[1];
    return Double.valueOf(PERCENT * (busytime) / (busytime + idletime)).doubleValue();
  } else {
    return 0.0;
  }
  } catch (Exception ex) {
  ex.printStackTrace();
  return 0.0;
  }
}
/**
  * 读取CPU信息.
  * @param proc
  * @return
  * @author GuoHuang
  */
private long[] readCpu(final Process proc) {
  long[] retn = new long[2];
  try {
  OutputStream().close();
  InputStreamReader ir = new InputStream());
  LineNumberReader input = new LineNumberReader(ir);
  String line = adLine();
  if (line == null || line.length() < FAULTLENGTH) {
    return null;
  }
  int capidx = line.indexOf("Caption");
  int cmdidx = line.indexOf("CommandLine");
  int rocidx = line.indexOf("ReadOperationCount");
  int umtidx = line.indexOf("UserModeTime");
  int kmtidx = line.indexOf("KernelModeTime");
  int wocidx = line.indexOf("WriteOperationCount");
  long idletime = 0;
  long kneltime = 0;
  long usertime = 0;
  while ((line = adLine()) != null) {
    if (line.length() < wocidx) {
    continue;
    }
    // 字段出现顺序：Caption,CommandLine,KernelModeTime,ReadOperationCount,
    // ThreadCount,UserModeTime,WriteOperation
    String caption = Bytes.substring(line, capidx, cmdidx - 1).trim();
    String cmd = Bytes.substring(line, cmdidx, kmtidx - 1).trim();
    if (cmd.indexOf("") >= 0) {
    continue;
    }
    String s1 = Bytes.substring(line, kmtidx, rocidx - 1).trim();
    String s2 = Bytes.substring(line, umtidx, wocidx - 1).trim();
    if (caption.equals("System Idle Process") || caption.equals("System")) {
    if (s1.length() > 0)
      idletime += Long.valueOf(s1).longValue();
    if (s2.length() > 0)
      idletime += Long.valueOf(s2).longValue();
    continue;
    }
    if (s1.length() > 0)
    kneltime += Long.valueOf(s1).longValue();
    if (s2.length() > 0)
    usertime += Long.valueOf(s2).longValue();
  }
  retn[0] = idletime;
  retn[1] = kneltime + usertime;
  return retn;
  } catch (Exception ex) {
  ex.printStackTrace();
  } finally {
  try {
    InputStream().close();
  } catch (Exception e) {
    e.printStackTrace();
  }
  }
  return null;
}
/**
  * 测试方法.
  *
  * @param args
  * @throws Exception
  * @author GuoHuang
  */
public static void main(String[] args) throws Exception {
  IMonitorService service = new MonitorServiceImpl();
  MonitorInfoBean monitorInfo = MonitorInfoBean();
  System.out.println("cpu占有率=" + CpuRatio());
  System.out.println("可使用内存=" + TotalMemory());
  System.out.println("剩余内存=" + FreeMemory());
  System.out.println("最大可使用内存=" + MaxMemory());
  System.out.println("操作系统=" + OsName());
  System.out.println("总的物理内存=" + TotalMemorySize() + "kb");
  System.out.println("剩余的物理内存=" + FreeMemory() + "kb");
  System.out.println("已使用的物理内存=" + UsedMemory() + "kb");
  System.out.println("线程总数=" + TotalThread() + "kb");
}
}
该实现类中需要用到一个自己编写byte的工具类，该类的代码如下所示：
package com.itor;
/**
* byte操作类.
*/
public class Bytes {
/**
  * 由于String.subString对汉字处理存在问题（把一个汉字视为一个字节)，因此在 包含汉字的字符串时存在隐患，现调整如下：
  *
  * @param src 要截取的字符串
  * @param start_idx 开始坐标（包括该坐标)
  * @param end_idx 截止坐标（包括该坐标）
  * @return
  */
public static String substring(String src, int start_idx, int end_idx) {人力资源的六大板块
  byte[] b = Bytes();
  String tgt = "";
  for (int i = start_idx; i <= end_idx; i++) {
  tgt += (char) b[i];
  }
  return tgt;
}
}
运行下MonitorBeanImpl类，读者将会看到当前的内存、cpu利用率等信息。就算候鸟已南飞

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