实现log日志输出_类log4j

当一个项目在长久运行，log日志在控制台看的并不方便。

我们可以将一些我们需要的东西打印出来，存储到一个log日志当中。

于是诞生了这个小demo

demo中可以每天在指定目录生成一个log日志。当然这里只是给出一个思路，你可以根据你的需要去更改这些代码。如果想要专业点的日志打印，还是推荐使用log4j插件。

package com.againfly.log;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;

public class LogOutPut {
	private volatile static LogOutPut instance = null;

	private String logPath = "C://log//";
	
	private static SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss");
	private static SimpleDateFormat logFormat = new SimpleDateFormat("yyyy_MM_dd");
	private File log = null;
	private PrintWriter out = null;
	private String logFileName = null;
	
	private LogOutPut(){
		createLogFile();
	}
	
	public void outLog(String msg){
		createLogFile();
		out.print(timeFormat.format(new Date()) + "    ---->    " + msg);
	} 
	
	public static LogOutPut getInstance(){
		if(null == instance){
			synchronized (LogOutPut.class) {
				if(null == instance){
					instance = new LogOutPut();
				}
			}
		}
		return instance;
	}
	
	private void createLogFile(){
		String genLogFileName = logFormat.format(new Date());
		if(genLogFileName.equals(logFileName)){
			return;
		}
		File dir = new File(logPath);
		if(!dir.exists())	dir.mkdirs();
		
		logFileName = genLogFileName;
		log = new File(logPath + logFileName + ".log");
		try{
			if(!log.exists())	log.createNewFile();
			if(out != null)		out.close();
			out = new PrintWriter(new OutputStreamWriter(new FileOutputStream(log, true), "UTF-8"), true);
		}catch(IOException e){
			e.printStackTrace();
		}
	}
	
}