如何在 Spring 引导中使用 restTemplate 检索资源 object？

Question

所以，基本上是标题。

我有 2 个微服务。一个生成并发送一个 zip 文件，另一个接收它，然后施展魔法，将其转换为字节数组 []，然后将其发送到其他地方。但这只是理论上的 - 我无法让它发挥作用。

我需要下载一个包含 InputStream 的资源 (https://docs.spring.io/spring-framework/docs/3.2.x/spring-framework-reference/html/resources.html)，我生成的 zip 存档被打包到其中。将它写在 HttpServletResponse 的 OutputStream 中对我不起作用，因为我无法使用它 - 稍后我需要操作文件，这种方法仅适用于浏览器下载 (?)

所以我在第一个微服务中这样做了：

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        BufferedOutputStream bos = new BufferedOutputStream(baos);
        ZipOutputStream zos = new ZipOutputStream(bos);
        try {
            zos = service.generateZip(blablabla, zos);

            baos.close();
            bos.close();
            zos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

        ByteArrayResource resource = new ByteArrayResource(baos.toByteArray());    

        ResponseEntity<Resource> response = ResponseEntity.ok()
                    .contentType(MediaType.parseMediaType("application/zip;charset=UTF-8"))
                    .contentLength(resource.contentLength())
                    .header(HttpHeaders.CONTENT_DISPOSITION,
                            ContentDisposition.parse(format("attachment; filename=\"doc_%s.zip\"", id)).toString())
                    .body(resource);

第二个：

    public byte[] getZip(DocRequest request) throws IOException {
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/zip;charset=UTF-8"));
        headers.setAccept(Collections.singletonList(MediaType.parseMediaType("application/zip;charset=UTF-8")));
        // headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        // headers.setAccept(Collections.singletonList(MediaType.APPLICATION_OCTET_STREAM));

        Resource response = restTemplate.exchange(
                        apiUrl + "/doc/get-zip/" + request.getId(),
                        HttpMethod.GET,
                        new HttpEntity<>(null, headers),
                        Resource.class)
                .getBody();

        return (response != null) ? IOUtils.toByteArray(response.getInputStream()) : null;
    }

还添加了 ResourceHttpMessageConverter 到 restTemplate 到两个微服务的配置：

        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        converter.setSupportedMediaTypes(Collections.singletonList(MediaType.ALL));
        converter.setObjectMapper(objectMapper);

        ResourceHttpMessageConverter resourceConverter = new ResourceHttpMessageConverter();
        resourceConverter.setSupportedMediaTypes(Collections.singletonList(MediaType.ALL));

        return builder.interceptors(...)
                .messageConverters(resourceConverter, converter)
                .configure(restTemplate);

没有它们，我会收到如下所示的错误：

{"method":"POST","exceptionName":"RestClientException","detail":"Error while extracting response for type [interface org.springframework.core.io.Resource] and content type [application/octet-stream]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Invalid UTF-8 middle byte 0x59; nested exception is com.fasterxml.jackson.core.JsonParseException: Invalid UTF-8 middle byte 0x59\n at [Source: (ByteArrayInputStream); line: 1, column: 13]"}

或

{"method":"POST","exceptionName":"RestClientException","detail":"Error while extracting response for type [interface org.springframework.core.io.Resource] and content type [application/zip;charset=UTF-8]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Invalid UTF-8 start byte 0x91; nested exception is com.fasterxml.jackson.core.JsonParseException: Invalid UTF-8 start byte 0x91\n at [Source: (ByteArrayInputStream); line: 1, column: 12]"}

取决于内容类型（分别为application/octet-stream和application/zip（application/zip；字符集=UTF-8））。

在我添加 ResourceHttpMessageConverter 之后，它现在给了我

{"method":"POST","exceptionName":"RestClientException","detail":"Error while extracting response for type [interface org.springframework.core.io.Resource] and content type [application/octet-stream]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Unrecognized token 'PK\u0003..': was expecting ('true', 'false' or 'null'); nested exception is com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'PK\u0003...': was expecting ('true', 'false' or 'null')\n at [Source: (ByteArrayInputStream); line: 1, column: 28]"}

可能是我用错了？任何意见，将不胜感激。提前谢谢你

Answer 1

最终将字节数组编码为 base64 字符串，然后将其作为

发送

return ResponseEntity.ok().body(Base64Utils.encodeToString(baos.toByteArray()));

然后在我的接收微服务中，我将以下内容添加到我的 restTemplate 配置中：

// idk if it's need to put StringHttpMessageConverter first in the list, but I did it just in case
List<HttpMessageConverter<?>> messageConverters = new ArrayList<>();
messageConverters.add(new StringHttpMessageConverter());
messageConverters.add(new MappingJackson2HttpMessageConverter());
restTemplate.setMessageConverters(messageConverters);

成功了！

不知道对不对，但也许有人会觉得有用

如何在 Spring 引导中使用 restTemplate 检索资源 object？

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