Linux下CPU、內存的利用率－－調用命令獲取（一）

 

Linux下CPU、內存的利用率－－調用命令獲取（一）

       怎麼獲取系統資源利用率，可以通過直接執行linux下的top命令實現。但需要注意Linux的版本問題，不同的版本輸出內容格式不一樣。這種方法不適合頻繁調用。

這個例子只包含獲取CPU利用率，內存的獲取原理一樣。

 

import java.io.*;
import java.util.StringTokenizer;

/** *//**
 * @author nineday
 * 下午04:09:46, 2007-12-10
 */
public class Execute ...{
    //private static final File memFile = new File("/proc/meminfo");
    private static final File versionFile = new File("/proc/version");
    private static String linuxVersion = null;
    
    
    static ...{
        InputStreamReader isr = null;
        BufferedReader brVer = null;
        StringTokenizer tokenVer = null;
        try...{
            isr = new InputStreamReader(new FileInputStream(versionFile));
            brVer = new BufferedReader(isr);
            tokenVer = new StringTokenizer(brVer.readLine());
            tokenVer.nextToken();
            tokenVer.nextToken();
            
            String version = tokenVer.nextToken();
            linuxVersion = version.subSequence(0, 3).toString();
            System.out.println("Linux version:"+linuxVersion);
        }catch(Exception e)...{
            e.printStackTrace();
        }finally...{
            freeResource(null, isr, brVer);
        }
    }
    
    
    //the test code
    public static void main(String[] args) ...{
        try ...{
            float usage = getCUPUsage();
            System.out.println("CPU usage: "+usage);
        } catch (Exception e) ...{
            e.printStackTrace();
        }
    }
    
    
    
    /** *//**
     * @return between 1 and 0
     */
    private static float getCUPUsage()...{
        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());
        }
    }
    
    
}