Java IO 日志

package com.demo;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class MercuryLog {

	public void writeException(String exceptionStr){
		
		SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
		String logFileName = "log/"+ dateFormat.format(new Date()) + ".txt";
		
		File logDir=new File("log");
		if(!logDir.exists()){
			logDir.mkdir();
		}
		
		File f = new File(logFileName);
		FileWriter fileWriter = null;
		try {
			if (!f.exists()) {
				fileWriter = new FileWriter(logFileName);
			} else {
				fileWriter = new FileWriter(f);
			}
			fileWriter.write(exceptionStr);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (fileWriter != null) {
				try {
					fileWriter.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
		System.out.println(f.getAbsolutePath());
	}
}