SpringMVC实现文件下载功能

2025-05-29 0 90

本文实例为大家分享了SpringMVC文件下载的具体代码,供大家参考,具体内容如下

两个案例

  1.为登录用户提供下载服务。

  2.阻止仅通过输入网址即可获取下载。

文件下载概览

  为了将文件发送给浏览器,我们需要在控制器中完成以下操作:

  • 对请求处理方法使用void返回类型,并且在方法中添加HttpServletResponse参数。
  • 将响应的内容类型设为文件的内容类型。Content-Type标题在某个实体的body中定义数据的类型,并包含媒体类型和子类型标识符。如果不清楚内容类型,并且希望浏览器失始终显示保存对话框,则将它设为APPLICATION/OCTET-STREAM。这个值时不区分大小写的。
  • 添加一个名为Content-Disposition的HTTP响应标题,并赋值attachment;filename=fileName,这里的fileName是默认的文件名。

案例1:为登录用户提供下载服务

Domain类

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package domain;

public class Login {

private String username;

private String password;

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

}

Controller控制器

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package controller;

import domain.Login;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.springframework.stereotype.Controller;

import org.springframework.ui.Model;

import org.springframework.web.bind.annotation.ModelAttribute;

import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import java.io.*;

@Controller

public class ResourceController {

private static final Log logger = LogFactory.getLog(ResourceController.class);

@RequestMapping(value = "/login")

public String login(@ModelAttribute Login login, HttpSession session, Model model)

{

model.addAttribute("login",new Login());

if("ms".equals(login.getUsername())&&"123".equals(login.getPassword()))

{

session.setAttribute("loggedIn",Boolean.TRUE);

return "Main";

}

else

{

return "LoginForm";

}

}

@RequestMapping(value = "/resource_download")

public String downloadResource(HttpSession session, HttpServletRequest request, HttpServletResponse response)

{

if(session==null||session.getAttribute("loggedIn")==null)

{

return "LoginForm";

}

String dataDirectory = request.getServletContext().getRealPath("/WEB-INF/data");

File file = new File(dataDirectory,"Blog.zip");

if(file.exists())

{

response.setContentType("application/octet-stream");

response.addHeader("Content-Disposition","attachment;filename=Blog.zip");

byte[] buffer = new byte[1024];

FileInputStream fis =null;

BufferedInputStream bis =null;

try {

fis = new FileInputStream(file);

bis = new BufferedInputStream(fis);

OutputStream os =response.getOutputStream();

int i =bis.read(buffer);

while (i!=-1) {

os.write(buffer, 0, i);

i=bis.read(buffer);

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}finally {

try {

bis.close();

} catch (IOException e) {

e.printStackTrace();

}

try {

fis.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

return null;

}

}

编写视图

Main.jsp

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

<html>

<head>

<title>DownPage</title>

</head>

<body>

<h4>点击链接下载文件</h4>

<p>

<a href="resource_download" rel="external nofollow" >Down</a>

</p>

</body>

</html>

LoginForm.jsp

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

<html>

<head>

<title>登录页面</title>

</head>

<body>

<form:form commandName="login" action="login" method="post">

账号: <br>

<form:input path="username" cssErrorClass="error" id="username"/>

<br> 密码: <br>

<form:input path="password" cssErrorClass="error" id="password"/>

<br> <input type="submit" value="提交">

</form:form>

</body>

</html>

案例2:阻止仅通过输入网址即可获取下载

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@RequestMapping(value = "/resource_download")

public String downloadResource(HttpSession session, HttpServletRequest request, HttpServletResponse response,@RequestHeader String refuer

){

if(refer==null) //通过判断refer来浏览器输入网址就能下载图片的情况

{

  return "LoginForm";

}

String dataDirectory = request.getServletContext().getRealPath("/WEB-INF/data");

File file = new File(dataDirectory,"Blog.zip");

if(file.exists())

{

response.setContentType("application/octet-stream");

response.addHeader("Content-Disposition","attachment;filename=Blog.zip");

byte[] buffer = new byte[1024];

FileInputStream fis =null;

BufferedInputStream bis =null;

try {

fis = new FileInputStream(file);

bis = new BufferedInputStream(fis);

OutputStream os =response.getOutputStream();

int i =bis.read(buffer);

while (i!=-1) {

os.write(buffer, 0, i);

i=bis.read(buffer);

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}finally {

try {

bis.close();

} catch (IOException e) {

e.printStackTrace();

}

try {

fis.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

return null;

}

}

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