JavaWeb实现文件的上传与下载

<%@ page language="java" cOntentType="text/html; charset=UTF-8"
 pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>


 
 
 
 
 
 
 头像：
 
 
 

<%@ page language="java" cOntentType="text/html; charset=UTF-8"
 pageEncoding="UTF-8"%>







 
 
 
 
 

package cn.yz123123.controller;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

@WebServlet("/fileUpload")
@MultipartConfig
public class fileUpload extends HttpServlet {
 private static final long serialVersiOnUID= 1L;
 
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doPost(request, response);
 }

 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 //String username = request.getParameter("username");
 Part part = request.getPart("img");
 
 //获取文件的真实名称
 String header = part.getHeader("content-disposition");
 String realName = header.substring(header.indexOf("filename=")+10, header.length()-1);
 
 //获取文件自身流
 InputStream inputStream = part.getInputStream();
 
 //获取file真实路径，如果没有则创建
 String dir = request.getServletContext().getRealPath("/file/");
 File dirFile = new File(dir);
 //上面只是实例化了一个对象，并没有真正的创建一个文件夹
 if (!dirFile.exists()) {
 dirFile.mkdirs();
 }
 
 //创建文件对象，并用流的形式写在相应的文件夹中
 File file = new File(dir, realName);
 FileOutputStream fileOutputStream = new FileOutputStream(file);
 
 byte[] buf = new byte[1024];
 int len;
 while((len=inputStream.read(buf))!=-1) {
 fileOutputStream.write(buf, 0, len);
 }
 
 fileOutputStream.close();
 inputStream.close();
 
 //以下为测试
 request.setAttribute("src", request.getContextPath()+"/file/"+realName);
 request.setAttribute("filename", realName);
 request.getRequestDispatcher("/result.jsp").forward(request, response);
 }
 
}

package cn.yz123123.controller;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.UUID;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = "/download")
public class fileDownload extends HttpServlet{

 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 String filename = req.getParameter("filename");
 
 //获取文件的真实路径
 String filePath = req.getServletContext().getRealPath("/file/"+filename);
 
 FileInputStream fileInputStream = new FileInputStream(filePath);
 
 resp.setCharacterEncoding("UTF-8");
 resp.setHeader("Content-Disposition","attachment;filename="+UUID.randomUUID()+filename);
 
 ServletOutputStream outputStream = resp.getOutputStream();
 
 byte[] buf = new byte[1024];
 int len;
 
 while((len=fileInputStream.read(buf))!=-1) {
 outputStream.write(buf, 0, len);
 }
 outputStream.close();
 fileInputStream.close();
 
 }
 
 @Override
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 super.doGet(req, resp);
 }
}