在windows下获取系统信息

首先
    创建一个Bean用来存贮要得到的信

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;
    }
}

    之后，建立bean的接口

public interface IMonitorService {
    public MonitorInfoBean getMonitorInfoBean() throws Exception;

}

  然后，就是最关键的，得到cpu的利用率，已用内存，可用内存，最大内存等信息。

import java.io.InputStreamReader;
import java.io.LineNumberReader;

import sun.management.ManagementFactory;

import com.sun.management.OperatingSystemMXBean;
import java.io.*;
import java.util.StringTokenizer;

/** 

 * 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 final File versionFile = new File("/proc/version");
    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 = this.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;
                }
                // log.info("line="+line);
                if (caption.equals("System Idle Process")
                        || caption.equals("System")) {
                    idletime += Long.valueOf(
                            Bytes.substring(line, kmtidx, rocidx - 1).trim())
                            .longValue();
                    idletime += Long.valueOf(
                            Bytes.substring(line, umtidx, wocidx - 1).trim())
                            .longValue();
                    continue;
                }

                kneltime += Long.valueOf(
                        Bytes.substring(line, kmtidx, rocidx - 1).trim())
                        .longValue();
                usertime += Long.valueOf(
                        Bytes.substring(line, umtidx, wocidx - 1).trim())
                        .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");
    }
}

    其中，Bytes类用来处理字符串

   public class Bytes {
    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;
    }
}