java.util.logging.FileHandler

 java.util.logging.FileHandler 

java自带的日志功能，FileHandler可以写日志到文件系统，并且自己维护日志的增删，比c++不知道强多少

 FileHandler(filename,2,2); 测试时只写2k，并只保留2个文件：

import java.io.IOException;
import java.util.logging.FileHandler;
import java.util.logging.Logger; // <= (1)

public class Loggertest {
    
    private static Logger log = Logger.getLogger(Loggertest.class.getSimpleName());// <= (2)
    public void sub()
    {
        String filename="D:\test\1.txt";
        FileHandler fh;
        try {
            fh = new FileHandler(filename,2,2);
            log.addHandler(fh);
            
            log.info("  1String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  2String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  3String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  4String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  5String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  6String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  7String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  8String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  9String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  10String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  11String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  12String userDir = System.getenv("USERPROFILE");");// <= (3)
            
            log.info("  13String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  14String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  15String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  16String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  17String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  18String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  19String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  20String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  21String userDir = System.getenv("USERPROFILE");");// <= (3)
            log.info("  22String userDir = System.getenv("USERPROFILE");");// <= (3)
        } catch (SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
    }

    public static void main(String[] args)
    {
        Loggertest logWorld = new Loggertest();
        logWorld.sub();
    }
}