springboot的WEB项目中实现文件上传

java中的文件上传一共涉及两个组件:CommonMultipartResolver和StandardServletMultipartResolver
而SpringBoot默认采用的MultipartResolver是StandardServletMultipartResolver

单文件上传

项目结构如下
springboot的WEB项目中实现文件上传_第1张图片

创建工程并添加相关依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

创建一个upload.html文件

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="uploadFile" value="请选择文件">
    <input type="submit" value="上传">
</form>
</body>
</html>

上传接口是upload,方法是post,enctype是multipart/form-data

后台新建一个控制器,用于对文件的保存以及返回访问路径

@RestController
public class FileUploadController {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
    @PostMapping("/upload")
    public String upload(MultipartFile uploadFile, HttpServletRequest request) {
        String realPath = ClassUtils.getDefaultClassLoader().getResource("static").getPath();//获得static路径
        String format = sdf.format(new Date());
        File folder = new File(realPath+"/"+format);//文件保存路径
        if(!folder.isDirectory()) {
            folder.mkdirs();
        }
        String oldName = uploadFile.getOriginalFilename();
        String newName = UUID.randomUUID().toString()+
                oldName.substring(oldName.lastIndexOf("."),oldName.length());
        try {
            uploadFile.transferTo(new File(folder,newName));//文件保存
            String filePath = request.getScheme() + "://" +request.getServerName()+":"+
                    request.getServerPort()+"/" +format+"/"+newName;
            return filePath;
        }catch (IOException e) {
            e.printStackTrace();
        }
        return "上传失败";
    }
}

开发者如果对图片上传细节进行配置可以在application.properties进行如下操作:

  • spring.servlet.multipart.enabled:表示是否开启文件上传支持,默认为true
  • spring.servlet.multipart.file-size-threshold:表示文件写入磁盘阈值,默认为0
  • spring.servlet.multipart.location:表示上传文件的临时保存位置
  • spring.servlet.multipart.max-file-size:表示单个文件的最大值,默认为1MB
  • spring.servlet.multipart.max-request-size:表示多个文件总大小,默认为10MB
  • spring.servlet.multipart.resolve-lazily:表示文件是否延迟解析,默认为false
spring.servlet.multipart.enabled=true
spring.servlet.multipart.file-size-threshold=0
spring.servlet.multipart.location=E://temp
spring.servlet.multipart.max-file-size=1MB
spring.servlet.multipart.max-request-size=10MB
spring.servlet.multipart.resolve-lazily=false

多文件上传

多文件是上传与单文件上传基本一致:
uploads.html如下

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/uploads" method="post" enctype="multipart/form-data" >
    <input type="file" name="uploadFiles" value="请选择文件" multiple>
    <input type="submit" value="上传">
</form>
</body>
</html>

而后台方法传入的参数则为文件数组,里面逻辑是遍历上传

@PostMapping("/uploads")
    public String uploads(MultipartFile[] uploadFiles, HttpServletRequest req) {
        String realPath = ClassUtils.getDefaultClassLoader().getResource("static").getPath();
        //req.getSession().getServletContext().getRealPath("/uploadFile/");
        String format = sdf.format(new Date());
        File folder = new File(realPath + "/" + format);
        if (!folder.isDirectory()) {
            folder.mkdir();
        }
        try {
        String filePaths = "";
        for(int i=0;i<uploadFiles.length;i++) {
            MultipartFile uploadFile=uploadFiles[i];
            String oldName = uploadFile.getOriginalFilename();
            String newName = UUID.randomUUID().toString() +
                    oldName.substring(oldName.lastIndexOf("."), oldName.length());

                uploadFile.transferTo(new File(folder, newName));
                String filePath = req.getScheme() + "://" + req.getServerName() + ":" +
                        req.getServerPort() + "/" + format + "/" + newName;
                filePaths = filePaths+","+ filePath;
            }
            return filePaths;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "上传失败";
    }

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