springmvc与swagger的集成

引子

由于我们公司在尝试着做前后端分离，那么后端的api文档是必须的，因此研究了一下swagger。swagger的2.0版本已经升级为springfox, 看这名字就知道springfox只能与springmvc做集成。

swagger介绍

1. Swagger-Core，swagger最核心的部分，能够根据注解来生成swagger definition（json或者yaml格式）
2. Swagger Codegen，顾名思义，根据swagger definition生成代码
3. Swagger UI，用来展示swagger definition的web项目
4. Swagger Editor，用来编辑swagger definition

本文主要涉及swagger-core，swagger-ui方面的内容

配置

1. 首先添加maven依赖，通过maven repository可以知道兼容的spring的最低版本是4.1.8.RELEASE

<dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.4.0</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.6.4</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.6.4</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.6.4</version>
        </dependency>

        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.4.0</version>
        </dependency>

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2.swagger config配置

package com.xxx.swagger;

import static com.google.common.collect.Lists.newArrayList;
import static springfox.documentation.builders.PathSelectors.ant;

import java.util.List;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.ImplicitGrantBuilder;
import springfox.documentation.builders.OAuthBuilder;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.ApiKey;
import springfox.documentation.service.AuthorizationScope;
import springfox.documentation.service.GrantType;
import springfox.documentation.service.LoginEndpoint;
import springfox.documentation.service.SecurityReference;
import springfox.documentation.service.SecurityScheme;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spi.service.contexts.SecurityContext;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger.web.ApiKeyVehicle;
import springfox.documentation.swagger.web.SecurityConfiguration;
import springfox.documentation.swagger2.annotations.EnableSwagger2;


@Configuration
@EnableWebMvc 
@EnableSwagger2 
@ComponentScan("com.xxx")
public class SpringfoxDocConfig {

    @Bean
    public Docket petApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo())
                .select()
                .build()
                .securitySchemes(newArrayList(oauth()))
                .securityContexts(newArrayList(securityContext()));

    }

    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("Springfox petstore API")
                .description("Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum " +
                        "has been the industry's standard dummy text ever since the 1500s, when an unknown printer "
                        + "took a " +
                        "galley of type and scrambled it to make a type specimen book. It has survived not only five " +
                        "centuries, but also the leap into electronic typesetting, remaining essentially unchanged. " +
                        "It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum " +
                        "passages, and more recently with desktop publishing software like Aldus PageMaker including " +
                        "versions of Lorem Ipsum.")
                .termsOfServiceUrl("http://springfox.io")
                .contact("springfox")
                .license("Apache License Version 2.0")
                .licenseUrl("https://github.com/springfox/springfox/blob/master/LICENSE")
                .version("2.0")
                .build();
    }

    @Bean
    SecurityContext securityContext() {
        AuthorizationScope readScope = new AuthorizationScope("read:pets", "read your pets");
        AuthorizationScope[] scopes = new AuthorizationScope[1];
        scopes[0] = readScope;
        SecurityReference securityReference = SecurityReference.builder()
                .reference("petstore_auth")
                .scopes(scopes)
                .build();

        return SecurityContext.builder()
                .securityReferences(newArrayList(securityReference))
                .forPaths(ant("/api/pet.*"))
                .build();
    }

    @Bean
    SecurityScheme oauth() {
        return new OAuthBuilder()
                .name("petstore_auth")
                .grantTypes(grantTypes())
                .scopes(scopes())
                .build();
    }

    @Bean
    SecurityScheme apiKey() {
        return new ApiKey("api_key", "api_key", "header");
    }

    List<AuthorizationScope> scopes() {
        return newArrayList(
                new AuthorizationScope("write:pets", "modify pets in your account"),
                new AuthorizationScope("read:pets", "read your pets"));
    }

    List<GrantType> grantTypes() {
        GrantType grantType = new ImplicitGrantBuilder()
                .loginEndpoint(new LoginEndpoint("http://petstore.swagger.io/api/oauth/dialog"))
                .build();
        return newArrayList(grantType);
    }

    @Bean
    public SecurityConfiguration securityInfo() {
        return new SecurityConfiguration("abc", "123", "pets", "petstore", "123", ApiKeyVehicle.HEADER, "", ",");
    }

}

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3.配置controller，这里仅举一例，详细完整的例子在springfox项目中的springfox-petstore模块里面

@Controller
@RequestMapping(value = "/api/user", produces = MediaType.APPLICATION_JSON_VALUE)
@Api(value = "/user", description = "Operations about user")
public class UserController {
  UserRepository userRepository = new UserRepository();

  static class UserRepository extends MapBackedRepository<String, User> {
  }

  @RequestMapping(value = "/{username}", method = GET)
  @ApiOperation(value = "Get user by user name", response = User.class)
  @ApiResponses(value = {
          @ApiResponse(code = 400, message = "Invalid username supplied"),
          @ApiResponse(code = 404, message = "User not found")})
  public ResponseEntity<User> getUserByName(
          @ApiParam(value = "The name that needs to be fetched. Use user1 for testing. ", required = true)
          @PathVariable("username") String username) {
    User user = userRepository.get(username);
    if (null != user) {
      return new ResponseEntity<User>(user, HttpStatus.OK);
    } else {
      throw new NotFoundException(404, "User not found");
    }
  }

}

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4.下载swagger-ui, 将dist目录copy到web项目中

5.测试一下，访问http://host:port/v2/api-docs应该可以下载swagger definition，访问http://host:port/swagger-ui/index.html会展现如下页面

6.在有些项目中spring mvc的请求是以某一后缀（url-pattern, 例如 .do）结尾的, 这样就要做一些必要的修改，在swagger-ui.js中，修改如下

 opts.responseContentType = $('div select[name=responseContentType]', $(this.el)).val();
      opts.requestContentType = $('div select[name=parameterContentType]', $(this.el)).val();
      $('.response_throbber', $(this.el)).show();

      // here, add suffix
      var suffix = ".do";
      if (!this.model.path.endsWith(suffix)) {
          this.model.path = this.model.path + suffix;
      }

      if (isFileUpload) {
        $('.request_url', $(this.el)).html('<pre></pre>');
        $('.request_url pre', $(this.el)).text(this.invocationUrl);

        opts.useJQuery = true;
        map.parameterContentType = 'multipart/form-data';
        this.map = map;
        return this.model.execute(map, opts, this.showCompleteStatus, this.showErrorStatus, this);
      } else {
        this.map = map;
        return this.model.execute(map, opts, this.showCompleteStatus, this.showErrorStatus, this);
      }

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这样在swagger里面try it out的时候，即能发出正确的请求了

springfox源码走读

我们请求的地址是http://host:port/v2/api-docs，这个请求是Swagger2Controller来处理的

@ApiIgnore
  @RequestMapping(value = "${springfox.documentation.swagger.v2.path:" + DEFAULT_URL + "}",
      method = RequestMethod.GET, produces = { APPLICATION_JSON_VALUE, HAL_MEDIA_TYPE })
  public
  @ResponseBody
  ResponseEntity<Json> getDocumentation(
      @RequestParam(value = "group", required = false) String swaggerGroup,
      HttpServletRequest servletRequest) {

    String groupName = Optional.fromNullable(swaggerGroup).or(Docket.DEFAULT_GROUP_NAME);
    Documentation documentation = documentationCache.documentationByGroup(groupName);
    if (documentation == null) {
      return new ResponseEntity<Json>(HttpStatus.NOT_FOUND);
    }
    Swagger swagger = mapper.mapDocumentation(documentation);
    if (isNullOrEmpty(swagger.getHost())) {
      swagger.host(hostName(servletRequest));
    }
    return new ResponseEntity<Json>(jsonSerializer.toJson(swagger), HttpStatus.OK);
  }

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文档的数据是从documentationCache里面拿的，那么documentationCache的数据又是怎么添加进去的呢？在DocumentationPluginsBootstrapper中，其实是一个监听器，接收到ContextRefreshedEvent事件后会扫描所有的文档插件

@Override
  public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
    if (initialized.compareAndSet(false, true)) {
      log.info("Context refreshed");
      List<DocumentationPlugin> plugins = pluginOrdering()
          .sortedCopy(documentationPluginsManager.documentationPlugins());
      log.info("Found {} custom documentation plugin(s)", plugins.size());
      for (DocumentationPlugin each : plugins) {
        DocumentationType documentationType = each.getDocumentationType();
        if (each.isEnabled()) {
          scanDocumentation(buildContext(each));
        } else {
          log.info("Skipping initializing disabled plugin bean {} v{}",
              documentationType.getName(), documentationType.getVersion());
        }
      }
    }
  }

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那么scan的具体细节又是什么呢？在ApiDocumentationScanner中我们看到DocumentationBuilder先组装context的全局配置，然后apiListingScanner.scan(listingContext)会扫描所有的controller的api信息，具体操作在ApiListingScanner的scan方法中

public Documentation scan(DocumentationContext context) {
    ApiListingReferenceScanResult result = apiListingReferenceScanner.scan(context);
    ApiListingScanningContext listingContext = new ApiListingScanningContext(context,
        result.getResourceGroupRequestMappings());

    Multimap<String, ApiListing> apiListings = apiListingScanner.scan(listingContext);
    DocumentationBuilder group = new DocumentationBuilder()
        .name(context.getGroupName())
        .apiListingsByResourceGroupName(apiListings)
        .produces(context.getProduces())
        .consumes(context.getConsumes())
        .host(context.getHost())
        .schemes(context.getProtocols())
        .basePath(context.getPathProvider().getApplicationBasePath())
        .tags(toTags(apiListings));

    Set<ApiListingReference> apiReferenceSet = newTreeSet(listingReferencePathComparator());
    apiReferenceSet.addAll(apiListingReferences(apiListings, context));

    ResourceListing resourceListing = new ResourceListingBuilder()
        .apiVersion(context.getApiInfo().getVersion())
        .apis(from(apiReferenceSet).toSortedList(context.getListingReferenceOrdering()))
        .securitySchemes(context.getSecuritySchemes())
        .info(context.getApiInfo())
        .build();
    group.resourceListing(resourceListing);
    return group.build();
  }

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总的来说springfox的原理比较简单，但是在文档格式的规定上比较严格

参考

http://swagger.io/ 
https://github.com/swagger-api/swagger-core/wiki/Annotations