一个不错的日志写入类

import java.io.*;
import java.util.*;
public class LogWriter {
private static final String DefalutLogFilePathName="c:\\logtext.log";//默认的日志文件的路径和文件名称
private static LogWriter logwriter; //该类的唯一的实例
private static InputStream fin; //属性配置文件的输入流
private static Properties pro; //class Properties′s supper is Hashtable class
private static PrintWriter out; //output stream
private static String logFileName; //output file name
private LogWriter() {
outInit();//init out put stream,实例化PrintWriter out 对象.
}
/**保存你想保存在日志文件中的信息,实现同步
* out put the message infomation
* @param message infomation
*/
public static synchronized void log(String message) {
if (logwriter == null || (out == null)){
logwriter = new LogWriter();
}
if (out != null) {
out.println(new java.util.Date() + ":" + message);
}
}
/**把异常信息保存在日志文件中,实现同步
* out put the Excetion infomation
* @param message infomation
*/
public static synchronized void log(Exception ex) {
if (logwriter == null || (out == null))
logwriter = new LogWriter();
if (out != null) {
out.println(new java.util.Date() + ":" );
ex.printStackTrace(out);
}
}
/**
*输出文件流的init
*/
private void outInit() {
if (logFileName == null)
logFileName = getlogFileName(); 从属性文件中类获得日志文件的路径
try {
if (out == null) {//如果输出i/o没有实例,则生成一个信的
out = new PrintWriter(new FileWriter(logFileName, true), true); ; //
其中的FileWriter()中的第二个参数的含义是:是否在文件中追加内容
}
}
catch (IOException ex) {
System.out.println("无法打开日志文件:"+logFileName);
ex.printStackTrace();
out = null;
}
}
/**
*根据配置文件.来获得日志文件的位置
*
* @return logFileName
*/
private String getlogFileName() {
try {
if (pro == null) {
pro = new java.util.Properties();
fin = getClass().getResourceAsStream("log.properties"); //在类的当前位置,查找属性配置文件log.properties
pro.load(fin);//载入配置文件
fin.close();
}
}
catch (IOException ex) {
System.err.println("无法打开属性配置文件: log.properties" );
ex.printStackTrace();
}
return pro.getProperty("logfile",DefalutLogFilePathName);
//根据属性值获得日志文件路径,第二个参数是:如果找不到"logfile"标志,就返回的默认值
}
/**你也可以在所有的日志都记录完成的时候,调用该方法,释放资源.
* free all the resouce,this is secuty method
*/
public void free() {
try {
this.logwriter = null;
if (out != null)
this.out.close();
if (fin != null)
this.fin.close();
}
catch (IOException ex) {
ex.printStackTrace();
}
}
}
//测试类

public class Do{
 
 public Do(){
 
 }
 
 public static void main(String[] args){
  
  try{
   LogWriter.log("张三登陆了该系统");
   LogWriter.log("张三删除了xxx条记录:记录id:");
  }
  catch (Exception ex) {
   LogWriter.log(ex);
  }

 }
}

log.properties文件内容

logfile=e:\\suoxin.log