首先在首頁添加下載下傳檔案的功能選項：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE HTML>
<html>
<head>
<title>初始頁面</title>
</head>
<body>
<h3>
<a href="${pageContext.request.contextPath}/Log/gologin">登入頁面</a>
</h3>
<h3>
<a href="${pageContext.request.contextPath}/Log/main">進入首頁</a>
</h3>
<h3>
<a href="${pageContext.request.contextPath}/Upload/goinput">檔案上傳</a>
</h3>
<h3>
<a href="${pageContext.request.contextPath}/Upload/godownload">檔案下載下傳</a>
</h3>
</body>
</html>
然後在Controller中寫請求：
//跳轉到下載下傳檔案界面
@RequestMapping("/godownload")
public String godownloads(){
return "download";
}
//下載下傳檔案
@RequestMapping("/download")
public String downloads(HttpServletResponse response , HttpServletRequest request) throws Exception{
//要下載下傳的圖檔位址
String path = request.getServletContext().getRealPath("input");
String fileName = "Java開發學習路線.png";
//設定response響應頭
response.reset();
response.setCharacterEncoding("UTF-8");
response.setContentType("multipart/form-data");
//設定響應頭
response.setHeader("Content-Disposition","attachment;fileName="+
URLEncoder.encode(fileName, StandardCharsets.UTF_8));
File file = new File(path,fileName);
//讀取檔案-輸出流
InputStream inputStream = new FileInputStream(file);
//寫檔案-輸出流
OutputStream outputStream = response.getOutputStream();
byte[] buff = new byte[1024];
int index = 0;
//執行寫出操作
while ((index=inputStream.read(buff))!=-1){
outputStream.write(buff,0,index);
outputStream.flush();
}
outputStream.close();
inputStream.close();
return "downloadSuccess";
}
規定了要下載下傳檔案的路徑以及檔案名，更換要下載下傳的檔案隻需要改動這部分即可。
然後寫發送下載下傳請求的頁面：
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
Created by IntelliJ IDEA.
User: shadowpee
Date: 2021/1/25
Time: 23:47
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<a href="${pageContext.request.contextPath}/Upload/download">下載下傳圖檔</a>
<a href="${pageContext.request.contextPath}">回到首頁</a>
</body>
</html>
打開Tomcat伺服器試驗一下：
點選檔案下載下傳，跳轉到下載下傳檔案界面
點選發送下載下傳請求：
下載下傳成功，回到首頁。