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。
PS：得到局域网内所有主机名的方法
import java.net.InetAddress;import java.net.UnknownHostException;public class A { static public void main(String[] args) { try { //通过主机名称得到IP地址 InetAddress address = InetAddress.getByName("192.168.9.148"); System.out.println("192.168.9.148"+": "+address.getHostAddress());// 通过IP得到主机名称 String ips="192.168.9.",ip; InetAddress addip; for(int i=148;i<255;i++){ ip=ips+i; addip=InetAddress.getByName(ip); System.out.println(ip+": "+addip.getHostName()); } } catch(UnknownHostException uhe) { System.err.println("Unable to find: "+"192.168.9.148"); } } }