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



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