SpringMVC的文件上传与下载

1. 单文件上传

配置jsp页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>文件上传</title>
</head>
<body>
<form action="/file/fileUpload" method="post" enctype="multipart/form-data">
<input type="file" name="file"/>
    作者:<input type="text" name="author"/>
    <input type="submit" value="提交">
</form>
</body>
</html>

配置文件上传的解析器

在WEB-INF里创建upload文件夹

效果展示

<!--CommonsMultipartResolver文件上传解析器-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!--编码-->
    <property name="defaultEncoding" value="UTF-8"/>
    <property name="maxInMemorySize" value="500000"/>
</bean>

2. 多文件上传

编写jsp页面

Form表单加上enctype="multipart/form-data"

input 属性的name值必须保持一致

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>多文件上传</title>
</head>
<body>
<form action="/file/fileUploads" method="post" enctype="multipart/form-data">
    <input type="file" name="uploadFiles"/>
    <input type="file" name="uploadFiles"/>
    <input type="file" name="uploadFiles"/>
    作者:<input type="text" name="author"/>
    <input type="submit" value="提交">
</form>
</body>
</html>

@RequestMapping("/fileUploads")
public String fileMothers(HttpSession session, @RequestParam MultipartFile[] uploadFiles,String author) throws IOException {
    System.out.println("作者："+author);
    System.out.println(uploadFiles);
    /*如何处理文件*/
  for (MultipartFile file:uploadFiles) {
      if (!file.isEmpty()) {
          //获取文件名称
          String fileName = file.getOriginalFilename();
          //获取需要上传的路径
          String realPath = session.getServletContext().getRealPath("/WEB-INF/upload");
          //创建文件对象
          File uploadfile = new File(realPath + "\" + fileName);
          //如何上传文件
          file.transferTo(uploadfile);
      }
  }
    return "main";
}

实现handler文件

@RequestMapping("/springmvc")
@Controller
public class SpringMVCTest {
    /**
     *来一波上传文件 ,用@RequestParam注解来指定表单上的file为MultipartFile 
     */
    @RequestMapping("/fileUpload")
    public void fileUpload(@RequestParam("file") MultipartFile file){
        // 判断文件是否为空  
        if (!file.isEmpty()) {  
            try {  
                // 文件保存路径  
                String filePath = "E:\MySQL\springmvc_test\"  
                        + file.getOriginalFilename();  
                // 转存文件  
                System.out.println(filePath);
                file.transferTo(new File(filePath));
                File uploadDest = new File(filePath);  
                String[] fileNames = uploadDest.list();  
                for (int i = 0; i < fileNames.length; i++) {  
                    //打印出文件名  
                    System.out.println(fileNames[i]);  
                }  
            } catch (Exception e) {  
                e.printStackTrace();  
            }  
        }  
 
    }
}

注意：我上面没有返回字符串或者是ModelAndView。。虽然能上传文件，但是跳转页面会是404，如下图：

这里进行修改

/**
     *来一波上传文件 ,用@RequestParam注解来指定表单上的file为MultipartFile 
     */
    @RequestMapping("/fileUpload")
    public String fileUpload(@RequestParam("file") MultipartFile file){
        // 判断文件是否为空  
        if (!file.isEmpty()) {  
            try {  
                // 文件保存路径  
                String filePath = "E:\MySQL\springmvc_test\"  
                        + file.getOriginalFilename();  
                // 转存文件  
                System.out.println(filePath);
                file.transferTo(new File(filePath));
                File uploadDest = new File(filePath);  
                String[] fileNames = uploadDest.list();  
                for (int i = 0; i < fileNames.length; i++) {  
                    //打印出文件名  
                    System.out.println(fileNames[i]);  
                }  
            } catch (Exception e) {  
                e.printStackTrace();  
            }  
        }  
        // 重定向  
        return SUCCESS;
    }

3.文件下载

修改index.jsp，加入下载文件的超链接：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UYF-8">
<title>Insert title here</title>
</head>
<body>

    <form action="springmvc/fileUpload" method="post" enctype="multipart/form-data">  
    choose file:<input type="file" name="file">  
    <input type="submit" value="submit">   
    </form> 
    
    <br><br>
    <a href="springmvc/testResponseEntity">Test ResponseEntity</a

</body>
</html>

在Controller中添加对应 handler:

 @RequestMapping("/testResponseEntity")
    public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws IOException {
        byte[] body =null;
        ServletContext servletContext = session.getServletContext();
        InputStream in = servletContext.getResourceAsStream("/files/abc.txt");
        body = new byte[in.available()];
        in.read(body);
        
        HttpHeaders headers = new HttpHeaders();
        //添加头部信息
        headers.add("Content-Disposition", "attachment;filename=abc.txt");
        
        HttpStatus statusCode = HttpStatus.OK;
        
        ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(body, headers, statusCode);
        return response;
    }

点击超链接，左下角看到