SpringMVC实现文件下载功能

2024-07-13 10:05:20

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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

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

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.*;@Controllerpublic 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

<%@ 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

<%@ 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

 @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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