从 Spring Boot Rest 服务下载文件

rest java spring

2022-08-31 08:28:02

我正在尝试从Spring引导休息服务下载文件。

@RequestMapping(path="/downloadFile",method=RequestMethod.GET)
    @Consumes(MediaType.APPLICATION_JSON_VALUE)
    public  ResponseEntity<InputStreamReader> downloadDocument(
                String acquistionId,
                String fileType,
                Integer expressVfId) throws IOException {
        File file2Upload = new File("C:\\Users\\admin\\Desktop\\bkp\\1.rtf");
        HttpHeaders headers = new HttpHeaders();
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");
        InputStreamReader i = new InputStreamReader(new FileInputStream(file2Upload));
        System.out.println("The length of the file is : "+file2Upload.length());

        return ResponseEntity.ok().headers(headers).contentLength(file2Upload.length())
                .contentType(MediaType.parseMediaType("application/octet-stream"))
                .body(i);
        }

当我尝试从浏览器下载文件时，它开始下载，但总是失败。导致下载失败的服务是否存在任何问题？

答案 1

使用输入流资源的选项 1

给定输入流的资源实现。

仅当没有其他特定 Resource 实现>适用时，才应使用。特别是，在可能的情况下，首选 ByteArrayResource 或任何基于文件的资源实现。

@RequestMapping(path = "/download", method = RequestMethod.GET)
public ResponseEntity<Resource> download(String param) throws IOException {

    // ...

    InputStreamResource resource = new InputStreamResource(new FileInputStream(file));

    return ResponseEntity.ok()
            .headers(headers)
            .contentLength(file.length())
            .contentType(MediaType.APPLICATION_OCTET_STREAM)
            .body(resource);
}

InputStreamResource 文档建议的选项 2 - 使用 ByteArrayResource：

@RequestMapping(path = "/download", method = RequestMethod.GET)
public ResponseEntity<Resource> download(String param) throws IOException {

    // ...

    Path path = Paths.get(file.getAbsolutePath());
    ByteArrayResource resource = new ByteArrayResource(Files.readAllBytes(path));

    return ResponseEntity.ok()
            .headers(headers)
            .contentLength(file.length())
            .contentType(MediaType.APPLICATION_OCTET_STREAM)
            .body(resource);
}

答案 2

下面的示例代码对我有用，可能会对某人有所帮助。

import org.springframework.core.io.ByteArrayResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@RestController
@RequestMapping("/app")
public class ImageResource {

    private static final String EXTENSION = ".jpg";
    private static final String SERVER_LOCATION = "/server/images";

    @RequestMapping(path = "/download", method = RequestMethod.GET)
    public ResponseEntity<Resource> download(@RequestParam("image") String image) throws IOException {
        File file = new File(SERVER_LOCATION + File.separator + image + EXTENSION);

        HttpHeaders header = new HttpHeaders();
        header.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=img.jpg");
        header.add("Cache-Control", "no-cache, no-store, must-revalidate");
        header.add("Pragma", "no-cache");
        header.add("Expires", "0");

        Path path = Paths.get(file.getAbsolutePath());
        ByteArrayResource resource = new ByteArrayResource(Files.readAllBytes(path));

        return ResponseEntity.ok()
                .headers(header)
                .contentLength(file.length())
                .contentType(MediaType.parseMediaType("application/octet-stream"))
                .body(resource);
    }

}