如何處理Swagger Codegen的org.springframework.core.io.Resource

Question

我正在使用Spring Boot 2開發一個Web應用程序，它有兩個Spring項目協同工作：一個是通過REST API為應用程序邏輯提供服務的REST API服務器，另一個是負責呈現網頁和調用API服務器的Web項目。 Web項目使用Swagger Codegen自動生成用於調用API的類。

在API服務器中，我有一個控制器ResourceController ，其端點用於提供文件內容（即下載文件），如下所示

@GetMapping("/files/{uuid}")
@ResponseBody
public org.springframework.core.io.Resource getFile(@PathVariable String uuid) {
    String systemPath = fileService.getFilePath(uuid);
    return new FileSystemResource(systemPath);
}

在Web客戶端，Swagger使用轉換為的方法生成ResourceControllerApi

public io.swagger.client.model.Resource getFileUsingGET(String uuid) {...}

我想在Web項目中創建一個控制器，該控制器通過用戶瀏覽器和API服務器之間的請求和響應。 我試過了

@GetMapping("/client/files/{uuid}")
@ResponseBody
public io.swagger.client.model.Resource getFile(@PathVariable String uuid) {
    return resourceControllerApi.getFileUsingGET(uuid);
}

在調用API時（在客戶端Web上），我收到此錯誤

org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class io.swagger.client.model.Resource] and content type [image/jpeg]

我希望當我把網址如http://myweb/client/files/dee38be4-6ef9-460d-bc44-f1b93770ab83 ，瀏覽器下載文件內容。 我一直在尋找一種方法將io.swagger.client.model.Resource轉換為org.springframework.core.io.Resource但無法弄清楚。

以下是自動生成的io.swagger.client.model.Resource的內容

/*
 * NPA Marketplace REST API
 * API to manage NPA Marketplace.
 *
 * OpenAPI spec version: 1.0
 * 
 *
 * NOTE: This class is auto generated by the swagger code generator program.
 * https://github.com/swagger-api/swagger-codegen.git
 * Do not edit the class manually.
 */


package io.swagger.client.model;

import java.util.Objects;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonValue;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import io.swagger.client.model.InputStream;
import io.swagger.client.model.URI;
import io.swagger.client.model.URL;

/**
 * Resource
 */
@javax.annotation.Generated(value = "io.swagger.codegen.languages.JavaClientCodegen", date = "2018-03-08T14:55:08.754+07:00")
public class Resource {
  @JsonProperty("description")
  private String description = null;

  @JsonProperty("file")
  private java.io.File file = null;

  @JsonProperty("filename")
  private String filename = null;

  @JsonProperty("inputStream")
  private InputStream inputStream = null;

  @JsonProperty("open")
  private Boolean open = null;

  @JsonProperty("readable")
  private Boolean readable = null;

  @JsonProperty("uri")
  private URI uri = null;

  @JsonProperty("url")
  private URL url = null;

  public Resource description(String description) {
    this.description = description;
    return this;
  }

   /**
   * Get description
   * @return description
  **/
  @ApiModelProperty(value = "")
  public String getDescription() {
    return description;
  }

  public void setDescription(String description) {
    this.description = description;
  }

  public Resource file(java.io.File file) {
    this.file = file;
    return this;
  }

   /**
   * Get file
   * @return file
  **/
  @ApiModelProperty(value = "")
  public java.io.File getFile() {
    return file;
  }

  public void setFile(java.io.File file) {
    this.file = file;
  }

  public Resource filename(String filename) {
    this.filename = filename;
    return this;
  }

   /**
   * Get filename
   * @return filename
  **/
  @ApiModelProperty(value = "")
  public String getFilename() {
    return filename;
  }

  public void setFilename(String filename) {
    this.filename = filename;
  }

  public Resource inputStream(InputStream inputStream) {
    this.inputStream = inputStream;
    return this;
  }

   /**
   * Get inputStream
   * @return inputStream
  **/
  @ApiModelProperty(value = "")
  public InputStream getInputStream() {
    return inputStream;
  }

  public void setInputStream(InputStream inputStream) {
    this.inputStream = inputStream;
  }

  public Resource open(Boolean open) {
    this.open = open;
    return this;
  }

   /**
   * Get open
   * @return open
  **/
  @ApiModelProperty(value = "")
  public Boolean isOpen() {
    return open;
  }

  public void setOpen(Boolean open) {
    this.open = open;
  }

  public Resource readable(Boolean readable) {
    this.readable = readable;
    return this;
  }

   /**
   * Get readable
   * @return readable
  **/
  @ApiModelProperty(value = "")
  public Boolean isReadable() {
    return readable;
  }

  public void setReadable(Boolean readable) {
    this.readable = readable;
  }

  public Resource uri(URI uri) {
    this.uri = uri;
    return this;
  }

   /**
   * Get uri
   * @return uri
  **/
  @ApiModelProperty(value = "")
  public URI getUri() {
    return uri;
  }

  public void setUri(URI uri) {
    this.uri = uri;
  }

  public Resource url(URL url) {
    this.url = url;
    return this;
  }

   /**
   * Get url
   * @return url
  **/
  @ApiModelProperty(value = "")
  public URL getUrl() {
    return url;
  }

  public void setUrl(URL url) {
    this.url = url;
  }


  @Override
  public boolean equals(java.lang.Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    Resource resource = (Resource) o;
    return Objects.equals(this.description, resource.description) &&
        Objects.equals(this.file, resource.file) &&
        Objects.equals(this.filename, resource.filename) &&
        Objects.equals(this.inputStream, resource.inputStream) &&
        Objects.equals(this.open, resource.open) &&
        Objects.equals(this.readable, resource.readable) &&
        Objects.equals(this.uri, resource.uri) &&
        Objects.equals(this.url, resource.url);
  }

  @Override
  public int hashCode() {
    return Objects.hash(description, file, filename, inputStream, open, readable, uri, url);
  }


  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("class Resource {\n");

    sb.append("    description: ").append(toIndentedString(description)).append("\n");
    sb.append("    file: ").append(toIndentedString(file)).append("\n");
    sb.append("    filename: ").append(toIndentedString(filename)).append("\n");
    sb.append("    inputStream: ").append(toIndentedString(inputStream)).append("\n");
    sb.append("    open: ").append(toIndentedString(open)).append("\n");
    sb.append("    readable: ").append(toIndentedString(readable)).append("\n");
    sb.append("    uri: ").append(toIndentedString(uri)).append("\n");
    sb.append("    url: ").append(toIndentedString(url)).append("\n");
    sb.append("}");
    return sb.toString();
  }

  /**
   * Convert the given object to string with each line indented by 4 spaces
   * (except the first line).
   */
  private String toIndentedString(java.lang.Object o) {
    if (o == null) {
      return "null";
    }
    return o.toString().replace("\n", "\n    ");
  }

}

Answer 1

錯誤

org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class io.swagger.client.model.Resource] and content type [image/jpeg] 

是從線上發出的

ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);

在類io.swagger.client.ApiClient ，它由變量庫resttemplate的Swagger Codegen自動生成，即相當於運行命令java -jar swagger-codegen-cli.jar generate -i api-specs.json -l java --library resttemplate

該錯誤表明resttemplate不知道如何將響應數據轉換為io.swagger.client.model.Resource並提示我們創建合適的HttpMessageConverter 。 這是一個用於創建HttpMessageConverters並使用resttemplate注冊它們的教程 。

但是，在我的情況下， HttpMessageConverter不能成為解決方案，因為生成的io.swagger.client.model.Resource沒有屬性來保存API響應中的文件數據。 似乎Swagger Codegen誤解了API服務器上的控制器將返回org.springframework.core.io.Resource的JSON表示，從而生成計數器部分io.swagger.client.model.Resource用於在客戶端接收JSON數據，但API服務器實際上使用文件數據流而不是JSON進行響應。

我不知道這是否可能是Swagger Codegen的錯誤，或者我做錯了一些如何。

不過，我決定放棄在API服務器上使用org.springframework.core.io.Resource 。 相反，我將控制器的返回類型更改為ResponseEntity<byte[]>並手動配置響應頭以具有正確的內容類型和文件名，如下所示

ResourceController（API服務器）

@GetMapping("/files/{uuid}")
@ResponseBody
public ResponseEntity<byte[]> getFile(@PathVariable String uuid) {
    FileMetadata myFileData = fileService.getFileMetadata(uuid);
    org.springframework.core.io.Resource res = new FileSystemResource(myFileData.getPaht());
    byte[] data = IOUtils.toByteArray(res.getInputStream());
    HttpHeaders respHeaders = new HttpHeaders();
    respHeaders.setContentType(MediaType.valueOf(myFileData.getContentType()));
    respHeaders.setContentLength(res.getFile().length());
    respHeaders.setContentDispositionFormData("attachment", myFileData.getName());
    return new ResponseEntity<>(data ,respHeaders, HttpStatus.OK);
}

在Web客戶端，然后我將從API服務器接收的byte[]數據轉換為org.springframework.core.io.Resource ，並從API服務器傳遞響應頭。

Web客戶端服務器上的控制器

@GetMapping("/client/files/{uuid}")
@ResponseBody
public ResponseEntity<org.springframework.core.io.Resource> getFile(@PathVariable String uuid) {
    byte[] data = resourceControllerApi.getFileUsingGET(uuid);
    HttpHeaders responseHeader = (HttpHeaders) RequestContextHolder.getRequestAttributes().getAttribute("responseHeader", RequestAttributes.SCOPE_REQUEST);
    return new ResponseEntity<>(new ByteArrayResource(data), responseHeader, HttpStatus.OK);
}

關於我用來檢索響應頭的方式，因為我無法從生成的api類中獲取響應頭，所以我必須創建一個ClientHttpRequestInterceptor來獲取頭並將其作為請求屬性。

public class ResponseHeaderClientRequestInterceptor implements ClientHttpRequestInterceptor {
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        ClientHttpResponse response = execution.execute(request, body);
        HttpHeaders responseHeader = response.getHeaders();
        RequestAttributes requestAttrs = RequestContextHolder.getRequestAttributes();
        if (requestAttrs != null) {
            requestAttrs.setAttribute("responseHeader", responseHeader, RequestAttributes.SCOPE_REQUEST);
        }
        return response;
    }
}