springmvc--文件上传下载

Posted 2020-06-13

一.文件下载

// 文件下载
    @RequestMapping("/testResponseEntity")
    public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws IOException{
        byte[] body = null;
        
        InputStream in = session.getServletContext().getResourceAsStream("/file/abc.txt");
        System.out.println("inputstream" + in);
        body = new byte[in.available()];
        in.read(body);
        
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Disposition", "attachment;filename=abc.txt");
        
        ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(body, headers, HttpStatus.OK);
        return response;
    }

二.文件上传

springmvc为文件上传提供了直接的支持，这种支持是通过即插即用的MultipartResolver实现的。

spring用jakarta commons FileUpload技术实现了MultipartResolver实现类：CommonsMultipartResolver

下面看如何来实现

1.引进如下jar包

commons-fileupload.jar

commons-io.jar  (<-上面的jar的依赖包)

2.springmvc的配置文件中，配置如下

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UTF-8"></property>
        </bean>

3.前台代码如下：

<form action="testFileUpload" enctype="multipart/form-data" method="POST">
    File : <input type="file" name="file"><br>
    Desc : <input type="text" name="desc"><br>
    <input type="submit" value="Submit">
    </form>

4.后台代码如下：

    // 文件上传
    @RequestMapping(value="/testFileUpload")
    public String testFileUpload(@RequestParam("desc") String desc,
            @RequestParam("file") MultipartFile file) throws IOException{
        System.out.println("desc: "+ desc);
        System.out.println("file name: " + file.getOriginalFilename());
        System.out.println("file inputstream" + file.getInputStream());
        return "success";
    }