通过IO操作，写日志

import java.io.BufferedReader;
import java.io.FileWriter;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Date;
public class Test {

public Test() {
// TODO Auto-generated constructor stub
}

public static void main(String[] args) {
// TODO Auto-generated method stub
try {
//标准输入用InputStreamReader
InputStreamReader in=new InputStreamReader(System.in);
BufferedReader bin=new BufferedReader(in);

FileWriter fw=new FileWriter("t.txt",true);
PrintWriter pw=new PrintWriter(fw);

String line=null;
while((line=bin.readLine())!=null){
pw.println("=================");
pw.println(line);   //将读到的字符打印文件
pw.flush();//没打印一个字符，就将缓存区的内容输出
if(line.equals("exit"))//exit为停止符
break;
}
pw.print("====="+new Date()+"=====");//时间类
pw.println();
pw.println();
pw.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}