ZZ java获得CPU使用率,系统内存,虚拟机内存等情况(不用JNI or Sigar)

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：

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package com.hmw.system.monitor;
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) {
        this.totalMemory = totalMemory;
    }
    public long getTotalMemorySize() {
        return totalMemorySize;
    }
    public void setTotalMemorySize(long totalMemorySize) {
        this.totalMemorySize = totalMemorySize;
    }
    public int getTotalThread() {
        return totalThread;
    }
    public void setTotalThread(int totalThread) {
        this.totalThread = 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;
    }
}

package com.hmw.system.monitor;
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) {
  this.totalMemory = totalMemory;
}
public long getTotalMemorySize() {
  return totalMemorySize;
}
public void setTotalMemorySize(long totalMemorySize) {
  this.totalMemorySize = totalMemorySize;
}
public int getTotalThread() {
  return totalThread;
}
public void setTotalThread(int totalThread) {
  this.totalThread = 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：

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package com.hmw.system.monitor;
/**
* 获取系统信息的业务逻辑类接口.
*/
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;
}

package com.hmw.system.monitor;
/**
* 获取系统信息的业务逻辑类接口.
*/
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：

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package com.hmw.system.monitor;
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;
    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.getRuntime().totalMemory() / kb;
        // 剩余内存
        long freeMemory = Runtime.getRuntime().freeMemory() / kb;
        // 最大可使用内存
        long maxMemory = Runtime.getRuntime().maxMemory() / kb;
        OperatingSystemMXBean osmxb = (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
        // 操作系统
        String osName = System.getProperty("os.name");
        // 总的物理内存
        long totalMemorySize = osmxb.getTotalPhysicalMemorySize() / kb;
        // 剩余的物理内存
        long freePhysicalMemorySize = osmxb.getFreePhysicalMemorySize() / kb;
        // 已使用的物理内存
        long usedMemory = (osmxb.getTotalPhysicalMemorySize() - osmxb.getFreePhysicalMemorySize()) / kb;
        // 获得线程总数
        ThreadGroup parentThread;
        for (parentThread = Thread.currentThread().getThreadGroup(); parentThread.getParent() != null; parentThread = parentThread.getParent());
        int totalThread = parentThread.activeCount();
        double cpuRatio = 0;
        if (osName.toLowerCase().startsWith("windows")) {
            cpuRatio = this.getCpuRatioForWindows();
        } else {
            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.getRuntime().exec("top -b -n 1");
            is = process.getInputStream();
            isr = new InputStreamReader(is);
            brStat = new BufferedReader(isr);
            if (linuxVersion.equals("2.4")) {
                brStat.readLine();
                brStat.readLine();
                brStat.readLine();
                brStat.readLine();
                tokenStat = new StringTokenizer(brStat.readLine());
                tokenStat.nextToken();
                tokenStat.nextToken();
                String user = tokenStat.nextToken();
                tokenStat.nextToken();
                String system = tokenStat.nextToken();
                tokenStat.nextToken();
                String nice = tokenStat.nextToken();
                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 {
                brStat.readLine();
                brStat.readLine();
                tokenStat = new StringTokenizer(brStat.readLine());
                tokenStat.nextToken();
                tokenStat.nextToken();
                tokenStat.nextToken();
                tokenStat.nextToken();
                tokenStat.nextToken();
                tokenStat.nextToken();
                tokenStat.nextToken();
                String cpuUsage = tokenStat.nextToken();
                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.println(ioe.getMessage());
            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)
                isr.close();
            if (br != null)
                br.close();
        } catch (IOException ioe) {
            System.out.println(ioe.getMessage());
        }
    }
    /**
     * 获得CPU使用率.
     *
     * @return 返回cpu使用率
     * @author GuoHuang
     */
    private double getCpuRatioForWindows() {
        try {
            String procCmd = System.getenv("windir") + "\\system32\\wbem\\wmic.exe process get Caption,CommandLine,KernelModeTime,ReadOperationCount,ThreadCount,UserModeTime,WriteOperationCount";
            // 取进程信息
            long[] c0 = readCpu(Runtime.getRuntime().exec(procCmd));
            Thread.sleep(CPUTIME);
            long[] c1 = readCpu(Runtime.getRuntime().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 {
            proc.getOutputStream().close();
            InputStreamReader ir = new InputStreamReader(proc.getInputStream());
            LineNumberReader input = new LineNumberReader(ir);
            String line = input.readLine();
            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 = input.readLine()) != 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("wmic.exe") >= 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 {
                proc.getInputStream().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 = service.getMonitorInfoBean();
        System.out.println("cpu占有率=" + monitorInfo.getCpuRatio());
        System.out.println("可使用内存=" + monitorInfo.getTotalMemory());
        System.out.println("剩余内存=" + monitorInfo.getFreeMemory());
        System.out.println("最大可使用内存=" + monitorInfo.getMaxMemory());
        System.out.println("操作系统=" + monitorInfo.getOsName());
        System.out.println("总的物理内存=" + monitorInfo.getTotalMemorySize() + "kb");
        System.out.println("剩余的物理内存=" + monitorInfo.getFreeMemory() + "kb");
        System.out.println("已使用的物理内存=" + monitorInfo.getUsedMemory() + "kb");
        System.out.println("线程总数=" + monitorInfo.getTotalThread() + "kb");
    }
}

package com.hmw.system.monitor;
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;
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.getRuntime().totalMemory() / kb;
  // 剩余内存
  long freeMemory = Runtime.getRuntime().freeMemory() / kb;
  // 最大可使用内存
  long maxMemory = Runtime.getRuntime().maxMemory() / kb;
  OperatingSystemMXBean osmxb = (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
  // 操作系统
  String osName = System.getProperty("os.name");
  // 总的物理内存
  long totalMemorySize = osmxb.getTotalPhysicalMemorySize() / kb;
  // 剩余的物理内存
  long freePhysicalMemorySize = osmxb.getFreePhysicalMemorySize() / kb;
  // 已使用的物理内存
  long usedMemory = (osmxb.getTotalPhysicalMemorySize() - osmxb.getFreePhysicalMemorySize()) / kb;
  // 获得线程总数
  ThreadGroup parentThread;
  for (parentThread = Thread.currentThread().getThreadGroup(); parentThread.getParent() != null; parentThread = parentThread.getParent());
  int totalThread = parentThread.activeCount();
  double cpuRatio = 0;
  if (osName.toLowerCase().startsWith("windows")) {
   cpuRatio = this.getCpuRatioForWindows();
  } else {
   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.getRuntime().exec("top -b -n 1");
   is = process.getInputStream();
   isr = new InputStreamReader(is);
   brStat = new BufferedReader(isr);
   if (linuxVersion.equals("2.4")) {
    brStat.readLine();
    brStat.readLine();
    brStat.readLine();
    brStat.readLine();
    tokenStat = new StringTokenizer(brStat.readLine());
    tokenStat.nextToken();
    tokenStat.nextToken();
    String user = tokenStat.nextToken();
    tokenStat.nextToken();
    String system = tokenStat.nextToken();
    tokenStat.nextToken();
    String nice = tokenStat.nextToken();
    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 {
    brStat.readLine();
    brStat.readLine();
    tokenStat = new StringTokenizer(brStat.readLine());
    tokenStat.nextToken();
    tokenStat.nextToken();
    tokenStat.nextToken();
    tokenStat.nextToken();
    tokenStat.nextToken();
    tokenStat.nextToken();
    tokenStat.nextToken();
    String cpuUsage = tokenStat.nextToken();
    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.println(ioe.getMessage());
   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)
    isr.close();
   if (br != null)
    br.close();
  } catch (IOException ioe) {
   System.out.println(ioe.getMessage());
  }
}
/**
* 获得CPU使用率.
*
* @return 返回cpu使用率
* @author GuoHuang
*/
private double getCpuRatioForWindows() {
  try {
   String procCmd = System.getenv("windir") + "\\system32\\wbem\\wmic.exe process get Caption,CommandLine,KernelModeTime,ReadOperationCount,ThreadCount,UserModeTime,WriteOperationCount";
   // 取进程信息
   long[] c0 = readCpu(Runtime.getRuntime().exec(procCmd));
   Thread.sleep(CPUTIME);
   long[] c1 = readCpu(Runtime.getRuntime().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 {
   proc.getOutputStream().close();
   InputStreamReader ir = new InputStreamReader(proc.getInputStream());
   LineNumberReader input = new LineNumberReader(ir);
   String line = input.readLine();
   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 = input.readLine()) != 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("wmic.exe") >= 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 {
    proc.getInputStream().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 = service.getMonitorInfoBean();
  System.out.println("cpu占有率=" + monitorInfo.getCpuRatio());
  System.out.println("可使用内存=" + monitorInfo.getTotalMemory());
  System.out.println("剩余内存=" + monitorInfo.getFreeMemory());
  System.out.println("最大可使用内存=" + monitorInfo.getMaxMemory());
  System.out.println("操作系统=" + monitorInfo.getOsName());
  System.out.println("总的物理内存=" + monitorInfo.getTotalMemorySize() + "kb");
  System.out.println("剩余的物理内存=" + monitorInfo.getFreeMemory() + "kb");
  System.out.println("已使用的物理内存=" + monitorInfo.getUsedMemory() + "kb");
  System.out.println("线程总数=" + monitorInfo.getTotalThread() + "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：

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package com.hmw.system.monitor;
/**
* 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) {
        byte[] b = src.getBytes();
        String tgt = "";
        for (int i = start_idx; i <= end_idx; i++) {
            tgt += (char) b[i];
        }
        return tgt;
    }
}

package com.hmw.system.monitor;
/**
* 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) {
  byte[] b = src.getBytes();
  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。

本文来自CSDN博客

cxzforever

发表于 2009-12-01 22:14 柴子瞻阅读(1831) 评论(0) 编辑收藏

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