JavaWeb实现文件的上传与下载，供大家参考，具体内容如下
第一步：导包
导入commons-fileupload-1.3.3.jar和commons-io-2.4.jar两个依赖包
第二步：编写前端页面
1、提交页面 index.jsp
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun测试数据/jsp/jstl/core" prefix="c"%> <!DOCTYPE html> < html > < head > < meta charset = "UTF-8" > < title >Insert title here</ title > </ head > < body > < form action = "${pageContext.request.contextPath }/fileUpload" method = "post" enctype = "multipart/form-data" > 头像：< input type = "file" name = "img" accept = "image/*" /> < input type = "submit" value = "提交" /> </ form > </ body > </ html > |
2、结果页面 result.jsp
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html> < html > < head > < meta charset = "UTF-8" > < title >Insert title here</ title > </ head > < body > < center > < a href = "${pageContext.request.contextPath }/download?filename=${filename}" > < img alt = "xx" src = "${src }" > </ a > </ center > </ body > </ html > |
第三步：编写上传和下载代码
1、上传图片 fileUpload.java
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 |
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); }
} |
2、下载图片 fileDownload.java
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 |
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); } } |
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
原文链接：https://blog.csdn.net/weixin_56887067/article/details/115428749
查看更多关于JavaWeb实现文件的上传与下载的详细内容...