Serlvet学习笔记之四—对文件的操作

1.读文件

package com.demo;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.PrintWriter;

import javax.servlet.http.*;
public class ServletFileTest1 extends HttpServlet {
    public void doGet(HttpServletRequest req,HttpServletResponse res){
        try {
            req.setCharacterEncoding("gb2312");
            res.setContentType("text/html;charset=gb2312");
            PrintWriter pw=res.getWriter();
//创建一个FileReader
            FileReader f=new FileReader("D:\\myCount.txt");
            BufferedReader br=new BufferedReader(f);
            String numVal=br.readLine();
            br.close();     //一定要关闭文件流
            pw.println("从文件中读取的数据是： "+numVal);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void doPost(HttpServletRequest req,HttpServletResponse res){
        this.doGet(req, res);
    }
}

2.写文件

package com.demo;
import java.io.*;
import javax.servlet.http.*;
public class ServletFileTest2 extends HttpServlet{
    public void doGet(HttpServletRequest req,HttpServletResponse res){
        try {
            req.setCharacterEncoding("gb2312");
            res.setContentType("text/html;charset=gb2312");
            PrintWriter pw=res.getWriter();
//创建一个FileWriter
            FileWriter f=new FileWriter("D:\\myCount.txt");
            BufferedWriter bw=new BufferedWriter(f);
            bw.write("hello");    //会把原来文件中的信息给删除掉，相当于>
            bw.close();
            pw.println("向文件写入信息");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void dopost(HttpServletRequest req,HttpServletResponse res){
        this.doGet(req, res);
    }
}