SpingMVC文件的上传和下载

最新推荐文章于 2024-07-09 20:20:12 发布

原创最新推荐文章于 2024-07-09 20:20:12 发布 · 137 阅读

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本文详细介绍了如何使用SpringMVC进行单文件和多文件的上传，包括配置依赖、处理业务逻辑及JSP页面编写。同时，还讲解了文件下载的实现方法。

单文件上传
底层使用Apache fileupload组件完成上传，SpringMVC对这种方式进行了封装。

在pom.xml中添加相关的依赖

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.5</version>
</dependency>

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

springmvc添加文件上传的组件

<!-- 配置上传组件 -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"></bean>

web.xml中配置（不然的话会被DispatcherServlet拦截.jpg的资源请求，本例上传的是jpg图片）

<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.jpg</url-pattern>
</servlet-mapping>

JSP
在写JSP页面是需要注意：
(1)input的type设置为file.
(2)form的method设置为post(get请求只能将文件名传给服务器)
（3）form的enctype设置为multipart-form-data(如果不设置只能将⽂件名传给服务器)

<%--
  Created by IntelliJ IDEA.
  User: ASUS
  Date: 2020/3/2
  Time: 14:43
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <form action="/file/upload" method="post" enctype="multipart/form-data">
        <input type="file" name="jpg">
        <input type="submit" name="上传">
    </form>
</body>
</html>

Handler业务方法

@Controller
@RequestMapping("/file")
public class FileHandler {

    @PostMapping("/upload")
    public String upload(MultipartFile jpg, HttpServletRequest request){
        if(jpg.getSize() > 0){
            //获取保存上传文件的file路径（file是在root目录下）
            String path = request.getServletContext().getRealPath("file");
            //获取上传的文件名
            String name = jpg.getOriginalFilename();
            File file = new File(path, name);
            try {
                jpg.transferTo(file);
                //保存上传之后的文件路径
                request.setAttribute("path","/file/"+name);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return "upload";
    }
}

文件上传，就是将文件上传到java程序中。当Tomcat服务器关闭时，上传的文件就自然不存在了。上传的文件路径在：D:\apache-tomcat-7.0.78-windows-x64\apache-tomcat-7.0.78\webapps\ROOT\file\文件名。

常见的异常：java.io.FileNotFoundException: D:\apache-tomcat-7.0.78-windows-x64\apache-tomcat-7.0.78\webapps\ROOT\file\微信图片_20200227124400.jpg (系统找不到指定的路径。)
解决方式：我们在启动Tomcat之后，访问upload.jsp页面，然后我们在 D:\apache-tomcat-7.0.78-windows-x64\apache-tomcat-7.0.78\webapps\ROOT文件夹下手动创建一个file文件夹，然后在上传资源，就不会报此异常。

多文件上传

pom.xml中添加相关依赖

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.5</version>
</dependency>

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

<dependency>
    <groupId>jstl</groupId>
    <artifactId>jstl</artifactId>
    <version>1.2</version>
</dependency>

<dependency>
    <groupId>taglibs</groupId>
    <artifactId>standard</artifactId>
    <version>1.1.2</version>
</dependency>

JSP

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <form action="/file/uploads" method="post" enctype="multipart/form-data">
        file1:<input type="file" name="jpgs"/><br/>
        file2:<input type="file" name="jpgs"/><br/>
        file3:<input type="file" name="jpgs"/><br/>
        <input type="submit" value="上传"/>
    </form>
/body>
</html>

Handler业务方法

@PostMapping("/uploads")
public String uploads(MultipartFile[] jpgs, HttpServletRequest request){
    List<String> files = new ArrayList<>();
    for(MultipartFile jpg: jpgs){
        if(jpg.getSize() > 0 ){
             //获取保存上传文件的file路径
            String path = request.getServletContext().getRealPath("file");
            //获取上传的文件名
            String name = jpg.getOriginalFilename();
            File file = new File(path, name);
            try {
                jpg.transferTo(file);
                //保存上传之后的文件路径
                files.add("/file/"+name);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    request.setAttribute("files",files);
    return "uploads";
 }

下载
只有上传过资源才能下载
JSP

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <a href="/file/download/微信图片_20200227123338">微信图片_20200227123338.jpg</a>
    <a href="/file/download/浩天">浩天.jpg</a>
</body>
</html>

Handler业务代码

@GetMapping("/download/{name}")
public String download(@PathVariable("name") String name, HttpServletRequest request, HttpServletResponse response){
    if(name != null){
        name += ".png";
        String path = request.getServletContext().getRealPath("file");
        File file = new File(path,name);
        OutputStream outputStream = null;
        if(file.exists()){
            response.setContentType("application/forc-download");
            response.setHeader("Content-Disposition","attachment;filename="+name);
            try {
                outputStream = response.getOutputStream();
                outputStream.write(FileUtils.readFileToByteArray(file));
                outputStream.flush();
            } catch (IOException e) {
                e.printStackTrace();
            }finally {
                if(outputStream != null){
                    try {
                        outputStream.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
    return "upload";
}