使用Java代码获取服务器性能信息及局域网内主机名

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; 
 
   
public  class MonitorInfoBean { 
     
  private  long totalMemory; 
   
     
  private  long freeMemory; 
   
     
  private  long maxMemory; 
   
     
  private String osName; 
   
     
  private  long totalMemorySize; 
   
     
  private  long freePhysicalMemorySize; 
   
     
  private  long usedMemory; 
   
     
  private  int totalThread; 
   
     
  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; 
 
   
public  interface IMonitorService { 
     
  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; 
 
   
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 ; 
 
     
  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; 
  } 
 
     
  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 ; 
    } 
  } 
 
     
  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 ; 
  } 
   
     
  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; 
 
   
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; 
  } 
} 

 
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");
  }
 } 
 }