从Spring Boot Rest服务下载文件

78

我正在尝试从Spring Boot Rest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，但始终失败。该服务有什么问题导致下载失败？

java  spring  rest 
— 基兰
source

Answers:

148

选项1使用InputStreamResource

给定InputStream的资源实现。

仅当没有其他特定的资源实现>适用时才应使用。特别是，尽可能选择ByteArrayResource或任何基于文件的Resource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);
}

Option2作为InputStreamResource的文档建议-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);
}
— 命运
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2
我正在尝试针对Word文档.doc格式执行此操作，但是在下载格式时，格式消失了，下载的文件没有文件扩展名，并且文件名是下载时的响应。有什么建议吗？
— Tulsi Jain
17
@TulsiJain添加Content-Disposition HttpHeader： HttpHeaders headers = new HttpHeaders(); headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=myDoc.docx");
— fateddy
7
以防万一，您很不幸无法使用普通的Spring而不是Spring Boot，您需要确保将实例 ResourceHttpMessageConverter添加到HttpMessageConverters列表中。创建一个@Configuration扩展类WebMvcConfigurerAdapter，实现configureMessageConverters（）方法并添加converters.add(new ResourceHttpMessageConverter());一行
— ashario
4
问题：选项1似乎没有关闭流。魔术在哪里？选项2似乎在发送之前将完整文件加载到内存中。正确？备择方案？谢谢！
— eventhorizo​​n
20

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);
    }

}
— 拉杰什·桑森（Rajesh Samson）
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4

我建议使用StreamingResponseBody，因为有了它，应用程序就可以直接写入响应（OutputStream），而无需占用Servlet容器线程。如果要下载很大的文件，这是一个好方法。

@GetMapping("download")
public StreamingResponseBody downloadFile(HttpServletResponse response, @PathVariable Long fileId) {

    FileInfo fileInfo = fileService.findFileInfo(fileId);
    response.setContentType(fileInfo.getContentType());
    response.setHeader(
        HttpHeaders.CONTENT_DISPOSITION, "attachment;filename=\"" + fileInfo.getFilename() + "\"");

    return outputStream -> {
        int bytesRead;
        byte[] buffer = new byte[BUFFER_SIZE];
        InputStream inputStream = fileInfo.getInputStream();
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
    };
}

附注：使用StreamingResponseBody时，强烈建议配置Spring MVC中使用的TaskExecutor来执行异步请求。TaskExecutor是一个抽象Runnable执行的接口。

更多信息：https : //medium.com/swlh/streaming-data-with-spring-boot-restful-web-service-87522511c071

— 费利佩·德斯达拉蒂
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1
我无法ResponseEntity<Resource>运行任何解决方案。StreamingResponseBody开箱即用的解决方案。谢谢！
— t0r0X
2

我想分享一种使用JavaScript（ES6），React和Spring Boot后端下载文件的简单方法：

  1. 春季启动休息控制器

来自org.springframework.core.io.Resource的资源

    @SneakyThrows
    @GetMapping("/files/{filename:.+}/{extraVariable}")
    @ResponseBody
    public ResponseEntity<Resource> serveFile(@PathVariable String filename, @PathVariable String extraVariable) {

        Resource file = storageService.loadAsResource(filename, extraVariable);
        return ResponseEntity.ok()
               .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + file.getFilename() + "\"")
               .body(file);
    }
  1. 使用AXIOS进行React，API调用

将responseType设置为arraybuffer以指定响应中包含的数据类型。

export const DownloadFile = (filename, extraVariable) => {
let url = 'http://localhost:8080/files/' + filename + '/' + extraVariable;
return axios.get(url, { responseType: 'arraybuffer' }).then((response) => {
    return response;
})};

最后一步>下载
的帮助下 JS文件下载 ，你可以触发浏览器，如果它被下载到数据保存到文件中。

DownloadFile('filename.extension', 'extraVariable').then(
(response) => {
    fileDownload(response.data, filename);
}
, (error) => {
    // ERROR 
});
— 费塔霍基
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2

如果需要从服务器的文件系统下载巨大的文件，则ByteArrayResource可以占用所有Java堆空间。在这种情况下，您可以使用FileSystemResource

— 塔拉斯瓜
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0 
    @GetMapping("/downloadfile/{productId}/{fileName}")
public ResponseEntity<Resource> downloadFile(@PathVariable(value = "productId") String productId,
        @PathVariable String fileName, HttpServletRequest request) {
    // Load file as Resource
    Resource resource;

    String fileBasePath = "C:\\Users\\v_fzhang\\mobileid\\src\\main\\resources\\data\\Filesdown\\" + productId
            + "\\";
    Path path = Paths.get(fileBasePath + fileName);
    try {
        resource = new UrlResource(path.toUri());
    } catch (MalformedURLException e) {
        e.printStackTrace();
        return null;
    }

    // Try to determine file's content type
    String contentType = null;
    try {
        contentType = request.getServletContext().getMimeType(resource.getFile().getAbsolutePath());
    } catch (IOException ex) {
        System.out.println("Could not determine file type.");
    }

    // Fallback to the default content type if type could not be determined
    if (contentType == null) {
        contentType = "application/octet-stream";
    }

    return ResponseEntity.ok().contentType(MediaType.parseMediaType(contentType))
            .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
            .body(resource);
}

要测试它，请使用邮递员

http：// localhost：8080 / api / downloadfile / GDD / 1.zip

— 张峰
source
0

使用Apache IO可能是复制Stream的另一种选择

@RequestMapping(path = "/file/{fileId}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<?> downloadFile(@PathVariable(value="fileId") String fileId,HttpServletResponse response) throws Exception {

    InputStream yourInputStream = ...
    IOUtils.copy(yourInputStream, response.getOutputStream());
    response.flushBuffer();
    return ResponseEntity.ok().build();
}

Maven依赖

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-io</artifactId>
        <version>1.3.2</version>
    </dependency>
— JPG格式
source
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