SpringBoot上传文件到后端服务器

一时失言乱红尘 2023-10-01 12:36 1阅读 0赞

定义上传文件的服务：

import org.springframework.web.multipart.MultipartFile;
    
    import java.nio.file.Path;
    
    public interface StorageService {
        long save(MultipartFile file, String dst) throws Exception;
    
        void deleteAll(Path path);
    }

上传服务的接口实现：

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.util.FileSystemUtils;
    import org.springframework.web.multipart.MultipartFile;
    
    import java.io.File;
    import java.nio.file.Files;
    import java.nio.file.Path;
    
    
    @Service
    public class FileSystemStorageService implements StorageService {
        @Autowired
        public FileSystemStorageService() {
    
        }
    
        @Override
        public long save(MultipartFile file, String uploadFilePath) throws Exception {
            if (file.isEmpty()) {
                throw new Exception("Failed to store empty file " + file.getOriginalFilename());
            }
    
            if (!Files.exists(Path.of(uploadFilePath))) {
                try {
                    Files.createDirectory(Path.of(uploadFilePath));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
    
            String filePath = uploadFilePath + file.getOriginalFilename();
            File dest = new File(filePath);
    
            long cnt = 0;
            try {
                cnt = Files.copy(file.getInputStream(), dest.toPath());
            } catch (Exception e) {
                e.printStackTrace();
            }
    
            return cnt;
        }
    
        @Override
        public void deleteAll(Path rootLocation) {
            FileSystemUtils.deleteRecursively(rootLocation.toFile());
        }
    }

上面是基础的上传服务，写好后，开始写spring boot的controller控制器：

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.*;
    import org.springframework.web.multipart.MultipartFile;
    
    import java.nio.file.Path;
    
    @Controller
    public class FileUploadController {
        private final StorageService storageService;
    
        @Value("${file.upload.path}")
        private String uploadFilePath;
    
        @Autowired
        public FileUploadController(StorageService storageService) {
            this.storageService = storageService;
        }
    
        @GetMapping("/upload_page")
        public String uploadPage() {
            //返回存放在resources/templates下面的my_file_upload.html文件。
            return "my_file_upload.html";
        }
    
        //触发动作对应my_file_upload.html里面的form表单中的action
        @PostMapping("/do_upload_action")
        @ResponseBody
        public String uploadFiles(@RequestPart MultipartFile file) {
            String fileName = file.getOriginalFilename();
            System.out.println("开始上传文件 " + fileName);
    
            long cnt = 0;
            try {
                cnt = storageService.save(file, uploadFilePath);
            } catch (Exception e) {
                e.printStackTrace();
            }
    
            return "上传字节数 " + cnt;
        }
    
        @GetMapping("/delete_file")
        @ResponseBody
        public String deleteFile() {
            storageService.deleteAll(Path.of(uploadFilePath));
            return "删除完成";
        }
    }

在FileUploadController里面用到了my\_file\_upload.html，my\_file\_upload.html需要放在resources/templates下面，my\_file\_upload.html代码内容：

my\_file\_upload.html里面的action="/do\_upload\_action"对应于FileUploadController中的uploadFiles（）函数。

最后，在application.properties里面定义默认的上传文件目录，这个路径是服务器的位置，即当浏览器（客户端）上传文件后，保存到application.properties定义的服务器上的这个文件目录下面。

file.upload.path=E:/web/

application类：

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    public class SpringUploadfileApplication {
        public static void main(String[] args) {
            SpringApplication.run(SpringUploadfileApplication.class, args);
        }
    }

至此完成。

下面测试，在浏览器输入地址 [http://localhost:8080/upload\_page][http_localhost_8080_upload_page]

服务器返回（浏览器出现）my\_file\_upload.html内容。随后选择一个文件，提交上传，浏览器页面跳转到 [http://localhost:8080/do\_upload\_action][http_localhost_8080_do_upload_action]

上传成功后，服务器返回上传文件的总字节数。

若直接在浏览器访问 [http://localhost:8080/delete\_file][http_localhost_8080_delete_file]

就会删除定义的服务器端文件存储目录所有内容。

[http_localhost_8080_upload_page]: http://localhost:8080/upload_page
[http_localhost_8080_do_upload_action]: http://localhost:8080/do_upload_action
[http_localhost_8080_delete_file]: http://localhost:8080/delete_file