java不用jni，也可以获得当前系统性能信息

最近做个项目，就是要取得cpu占有率等等的系统信息，一开始以为要用动态链接库了，但后来发现可以像下面这样做，不去调用jni，这样省去了很多看新技术的时间o(∩_∩)o...

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.amgkaka.performance;

/** */
/**
 * 监视信息的JavaBean类.
 * @author  amg
 * @version 1.0
 * Creation date: 2008-4-25 - 上午10:37:00
 */
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：

package
 com.amgkaka.performance;

/** */
/**
 * 获取系统信息的业务逻辑类接口.
 * @author amg * @version 1.0
 * Creation date: 2008-3-11 - 上午10:06:06
 */
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
     * @author amgkaka
     * Creation date: 2008-4-25 - 上午10:45:08
     */
    public
 MonitorInfoBean getMonitorInfoBean() 
throws
 Exception;

}

  该类的实现类MonitorServiceImpl如下所示：

package
 com.amgkaka.performance;

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

import
 sun.management.ManagementFactory;

import
 com.sun.management.OperatingSystemMXBean;

/** */
/**
 * 获取系统信息的业务逻辑实现类.
 * @author amg * @version 1.0 Creation date: 2008-3-11 - 上午10:06:06
 */
public
 
class
 MonitorServiceImpl 
implements
 IMonitorService {
    //可以设置长些，防止读到运行此次系统检查时的cpu占用率，就不准了
    private
 
static
 
final
 
int
 CPUTIME = 
5000
;

    private
 
static
 
final
 
int
 PERCENT = 
100
;

    private
 
static
 
final
 
int
 FAULTLENGTH = 
10
;

    /** */
/**
     * 获得当前的监控对象.
     * @return 返回构造好的监控对象
     * @throws Exception
     * @author amg     * Creation date: 2008-4-25 - 上午10:45:08
     */
    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();
        }

        // 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;
    }

    /** */
/**
     * 获得CPU使用率.
     * @return 返回cpu使用率
     * @author amg     * Creation date: 2008-4-25 - 下午06:05:11
     */
    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 amg     * Creation date: 2008-4-25 - 下午06:10:14
     */
    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 amg     * Creation date: 2008-4-30 - 下午04:47:29
     */
    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：

package
 com.amgkaka.performance;

/** */
/**
 * byte操作类.
 * @author amg * @version 1.0
 * Creation date: 2008-4-30 - 下午04:57:23
 */
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。