前言

Swagger2（基于openApi3）已经在17年停止维护了，取而代之的是 sagger3（基于openApi3），而国内几乎没有 sagger3使用的文档，百度搜出来的都是swagger2的使用，这篇文章将介绍如何在 java 中使用 openApi3（swagger3）。

一、swagger 3 的使用

Open API
OpenApi是业界真正的 api 文档标准，其是由 Swagger 来维护的，并被linux列为api标准，从而成为行业标准。

Swagger

swagger 是一个 api 文档维护组织，后来成为了 Open API 标准的主要定义者，现在最新的版本为17年发布的 Swagger3（Open Api3）。国内绝大部分人还在用过时的swagger2（17年停止维护并更名为swagger3）swagger2的包名为 io.swagger，而swagger3的包名为 io.swagger.core.v3。

SpringFox

SpringFox是 spring 社区维护的一个项目（非官方），帮助使用者将 swagger2 集成到 Spring 中。常常用于 Spring 中帮助开发者生成文档，并可以轻松的在spring boot中使用。目前已经支持 OpenAPI3 标准。

升级到 OpenAPI3（java 中 swagger1.x 对应 OpenAPI2、swagger 2.x对应OpenAPI3）官方文档

3.0 相关特性

• 支持 Spring 5，Webflux（仅请求映射支持，尚不支持功能端点）、Spring Integration
• 补充官方在 spring boot 的自动装配 pringfox-boot-starter 以后可以直接依赖一个 dependency
• 与2.0更好的规范兼容性
• 支持OpenApi 3.0.3
• 轻依赖 spring-plugin，swagger-core
• 现有的swagger2批注将继续有效并丰富开放式API 3.0规范

常用注解说明

@Api：用在请求的类上，表示对类的说明
  tags: 说明该类的作用，可以在UI界面上看到的注解
  value: 该参数没什么意义，在UI界面上也看到，所以不需要配置
 
@ApiOperation：用在请求的方法上，说明方法的用途、作用
  value: 说明方法的用途、作用
  notes: 方法的备注说明
 
@ApiImplicitParams：用在请求的方法上，表示一组参数说明
 
@ApiImplicitParam：用在@ApiImplicitParams注解中，指定一个请求参数的各个方面
  name：参数名
  value：参数的汉字说明、解释
  required：参数是否必须传
  paramType：参数放在哪个地方
      · header --> 请求参数的获取：@RequestHeader
      · query --> 请求参数的获取：@RequestParam
      · path（用于restful接口）--> 请求参数的获取：@PathVariable
      · body（不常用）
      · form（不常用）
  dataType：参数类型，默认String，其它值dataType="Integer"   
  defaultValue：参数的默认值
 
@ApiResponses：用在请求的方法上，表示一组响应
 
@ApiResponse：用在@ApiResponses中，一般用于表达一个错误的响应信息
  code：数字，例如400
  message：信息，例如"请求参数没填好"
  response：抛出异常的类
 
@ApiModel：用于响应类上，表示一个返回响应数据的信息，一般用在post创建的时候，使用@RequestBody这样的场景，请求参数无法使用@ApiImplicitParam注解进行描述的时候）
 
@ApiModelProperty：用在属性上，描述响应类的属性
  name：属性名
  value：属性的汉字说明、解释
 
@ApiParam 用于 Controller 中方法的参数说明，放在方法签名当中
  value：参数说明
  required：是否必填
 
@ApiIgnore：使用该注解忽略这个API

二、在项目中的使用

• 1、引入pom包，这里同时引入增强包knife4j

<!-- Swagger3 -->
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-boot-starter</artifactId>
    <version>3.0.0</version>
</dependency>
 
<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger-ui -->
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>3.0.0</version>
</dependency>
 
<!-- https://mvnrepository.com/artifact/com.github.xiaoymin/knife4j-spring-boot-starter -->
<dependency>
    <groupId>com.github.xiaoymin</groupId>
    <artifactId>knife4j-spring-boot-starter</artifactId>
    <version>3.0.3</version>
</dependency>

• 2、application.yml 添加配置，放在spring目录下面：
  Springfox使用的路径匹配是基于AntPathMatcher的，而Spring Boot 2.6.X使用的是PathPatternMatcher。

# ========================================================================
# 启动报错需要修改以下mvc配置 Failed to start bean 'documentationPluginsBootstrapper'
spring:
  mvc:
    pathmatch:
      matching-strategy: ant_path_matcher
# ========================================================================

• 3、升级spring boot到2.7.0，使用swagger 3.0报错
  升级spring boot到2.7.0，项目启动报错，项目使用swagger 3.0 ,具体版本是knife4j-spring-boot-starter的3.0.3，查找解决方案，都说修改配置文件（但是修改配置后仍然无效）或者新增配置类，过滤空情况，但是仍然还是解决了很长时间。报错信息：Caused by: java.lang.NullPointerException: Cannot invoke “org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()” because “this.condition” is null

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled. 
2022-06-04 12:30:54.079 [main] ERROR org.springframework.boot.SpringApplication - Application run failed 
org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
    at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181)
    at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54)
    at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356)
    at java.base/java.lang.Iterable.forEach(Iterable.java:75)
    at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155)
    at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295)
    at com.cloud.user.UserApplication.main(UserApplication.java:41)
Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
    at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56)
    at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113)
    at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89)
    at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:473)
    at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
    at java.base/java.util.TimSort.sort(TimSort.java:234)
    at java.base/java.util.Arrays.sort(Arrays.java:1307)
    at java.base/java.util.ArrayList.sort(ArrayList.java:1721)
    at java.base/java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:392)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:510)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
    at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107)
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91)
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82)
    at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100)
    at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178)
    ... 14 common frames omitted

解决方案

• 新增一个配置类，注意配置类不能放到swagger的配置类下，测试无效。配置Bean可以放在启动类下或者重新新增一个配置Bean，代码如下:

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.ReflectionUtils;
import org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping;
import springfox.documentation.spring.web.plugins.WebFluxRequestHandlerProvider;
import springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider;

import java.lang.reflect.Field;
import java.util.List;
import java.util.stream.Collectors;

@Slf4j
@Configuration
public class BeanPostProcessorConfig {

    @Bean
    public BeanPostProcessor springfoxHandlerProviderBeanPostProcessor() {
        return new BeanPostProcessor() {
            @Override
            public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
                if (bean instanceof WebMvcRequestHandlerProvider || bean instanceof WebFluxRequestHandlerProvider) {
                    customizeSpringfoxHandlerMappings(getHandlerMappings(bean));
                }
                return bean;
            }

            private <T extends RequestMappingInfoHandlerMapping> void customizeSpringfoxHandlerMappings(List<T> mappings) {
                List<T> copy = mappings.stream()
                        .filter(mapping -> mapping.getPatternParser() == null)
                        .collect(Collectors.toList());
                mappings.clear();
                mappings.addAll(copy);
            }

            @SuppressWarnings("unchecked")
            private List<RequestMappingInfoHandlerMapping> getHandlerMappings(Object bean) {
                try {
                    Field field = ReflectionUtils.findField(bean.getClass(), "handlerMappings");
                    field.setAccessible(true);
                    return (List<RequestMappingInfoHandlerMapping>) field.get(bean);
                } catch (IllegalArgumentException | IllegalAccessException e) {
                    throw new IllegalStateException(e);
                }
            }
        };
    }

}

• 4、添加自定义配置类：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.bind.annotation.CookieValue;
import org.springframework.web.context.request.async.DeferredResult;
import com.github.xiaoymin.knife4j.spring.annotations.EnableKnife4j;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.oas.annotations.EnableOpenApi;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.Contact;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
 
/**
 * 文档访问地址：http://ip:port/swagger-ui/index.html
 * 添加Knife4j可以导出导出离线文档，访问地址：http://ip:port/doc.html
 *
 */
 
@Configuration
@EnableKnife4j
@EnableOpenApi
@ConditionalOnProperty(value = "spring.profiles.active", havingValue = "dev")
//@Profile({"dev","test"})
public class SwaggerConfiguration {
 
    @Bean
    public Docket createRestApis() {
        return new Docket(DocumentationType.OAS_30)
                .enable(true)//是否启用：注意生产环境需要关闭
                .groupName("spring-boot-2.7.3")
                .genericModelSubstitutes(DeferredResult.class)
                .useDefaultResponseMessages(false)
                .forCodeGeneration(true)
                .ignoredParameterTypes(CookieValue.class)
                .apiInfo(apiInfo())
                .select()
                //以下拦截配置可以三选一，根据需要进行添加
                .apis(RequestHandlerSelectors.basePackage("com.qi.study.springboot.controller"))
                .apis(RequestHandlerSelectors.withClassAnnotation(Api.class))
                .apis(RequestHandlerSelectors.withMethodAnnotation(ApiOperation.class))
                .paths(PathSelectors.any())
                .build();
    }
 
    private ApiInfo apiInfo() {
        return new ApiInfoBuilder()
                .title("使用swagger生成的接口文档")
                .description("开发测试")
                // 服务条款URL
                .termsOfServiceUrl("https://www.baidu.com/")
                // 作者信息
                .contact(new Contact("qihh", "https://www.baidu.com/", "qihh@136.com"))
                .version("0.0.1")
                .build();
    }
 
}

• 5、添加拦截器配置，放行相关目录

import com.kfang.web.price.manager.interceptor.AuthorizationInterceptor;
import com.kfang.web.price.manager.interceptor.ContextInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import javax.annotation.Resource;


@Configuration
public class InterceptorConfiguration implements WebMvcConfigurer {

    @Resource
    private Environment env;

    @Resource
    private AuthorizationInterceptor authorizationInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        String[] swaggerExcludePathPatterns = {"/doc.html","/swagger**/**","/swagger-resources/**","/webjars/**","/v3/**"};
        registry.addInterceptor(new ContextInterceptor()).addPathPatterns("/**");
        if("dev".equals(env.getProperty("spring.profiles.active"))){
        }else{
            swaggerExcludePathPatterns = new String[0];
        }
        registry.addInterceptor(authorizationInterceptor)
                .excludePathPatterns("/user/logout")
                .excludePathPatterns("/user/login")

                .excludePathPatterns(swaggerExcludePathPatterns)
                .addPathPatterns("/**").order(-1);
    }

}

• 6、测试demo

@Api(tags = "用户",value = "用户")
@RestController
@RequestMapping(value = "/user", produces = {"application/json;charset=UTF-8"})
public class UserController {
 
    @ApiOperation("添加")
    @PostMapping("/add")
    @ApiResponses({
            @ApiResponse(message = "添加", code = 200, response = UserVO.class)
    })      
    public UserVO add(@RequestBody @Valid UserAddRequest userAddRequest) {
        // 将数据写到数据库
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userAddRequest, userVO);
        userVO.setId(1L);
        userVO.setCreateTime(LocalDateTime.now());
        userVO.setUpdateTime(LocalDateTime.now());
        return userVO;
    }
 
    @ApiOperation("修改")
    @PostMapping("/edit")
    @ApiResponses({
            @ApiResponse(message = "修改", code = 200, response = UserVO.class)
    })  
    public UserVO edit(@RequestBody @Valid UserEditRequest userEditRequest) {
        // 修改数据库的数据
        UserVO userVO = new UserVO();
        BeanUtils.copyProperties(userEditRequest, userVO);
        userVO.setUpdateTime(LocalDateTime.now());
        return userVO;
    }
 
    @ApiOperation("查找")
    @GetMapping("/find")
    @ApiResponses({
            @ApiResponse(message = "查找", code = 200, response = UserQueryRequest.class)
    })
    public List<UserVO> find(UserQueryRequest userQueryRequest) {
        return new ArrayList<>();
    }
 
    @ApiOperation("删除")
    @PostMapping("/delete")
    public void delete(Long id) {
        // 将数据库数据删除
    }
    
    @PostMapping(value = "/fileUpload")
    @ApiOperation(value = "文件上传")
    @ApiResponses({
            @ApiResponse(message = "文件上传", code = 200, response = AliyunUploadResult.class)
    })
    public String uploadFile(@RequestPart("file") MultipartFile file) {
        AliyunUploadRequest uploadRequest = new AliyunUploadRequest(file);
        AliyunUploadResult result = aliyunOss.fileUpload(uploadRequest);
        return successInfo(result);
    }
    
    
    @PostMapping(value = "/importDataDetail")
    @ApiOperation(value = "导入Excel源数据明细")
    @ApiResponses({
            @ApiResponse(message = "导入Excel源数据明细出参成功", code = 200, response = Boolean.class)
    })
    public String importDataDetail(@RequestPart("file") MultipartFile file,
                                   @RequestParam("cityId") String cityId) {
                                  
    }   
}

三，启动测试

• 1、访问swagger-ui页面：http://localhost:8080/swagger-ui/index.html
  

• 2、访问knife4j-ui页面：http://localhost:8080/doc.html

knife4j是springfox-swagger的增强UI实现，为Java开发者在使用Swagger的时候，提供了简洁、强大的接口文档体验。引入pom包，并开启@EnableKnife4j注解就可以使用。

• 3、设置安全密码登录配置：

server.port=8081
knife4j.enable=true
knife4j.basic.enable=true
knife4j.basic.username=admin
knife4j.basic.password=admin
knife4j.setting.language=zh-CN

登录界面：

四、@RequestParam和@RequestPart的区别

@RequestPart

• @RequestPart这个注解用在multipart/form-data表单提交请求的方法上。
• 支持的请求方法的方式MultipartFile，属于Spring的MultipartResolver类。这个请求是通过http协议传输的

@RequestParam

• @RequestParam支持’application/json’，也同样支持multipart/form-data请求

区别

当请求方法的请求参数类型不是String 或 MultipartFile / Part时，而是复杂的请求域时，@RequestParam 依赖Converter or PropertyEditor进行数据解析， RequestPart参考 ‘Content-Type’ header，依赖HttpMessageConverters 进行数据解析

当请求为multipart/form-data时，@RequestParam只能接收String类型的name-value值，@RequestPart可以接收复杂的请求域（像json、xml）；@RequestParam 依赖Converter or PropertyEditor进行数据解析， @RequestPart参考'Content-Type' header，依赖HttpMessageConverters进行数据解析

前台请求：
jsonData为Person对象的json字符串
uploadFile为上传的图片

后台接收：

• 1、@RequestPart可以将jsonData的json数据转换为Person对象

@RequestMapping("jsonDataAndUploadFile")
@ResponseBody
public String jsonDataAndUploadFile(@RequestPart("uploadFile") MultiPartFile uploadFile,
                                    @RequestPart("jsonData") Person person) {
    StringBuilder sb = new StringBuilder();
    sb.append(uploadFile.getOriginalFilename()).append(";;;"));
    return person.toString() + ":::" + sb.toString();
}

• 2、@RequestParam对于jsonData的json数据只能用String字符串来接收

@RequestMapping("jsonDataAndUploadFile")
@ResponseBody
public String jsonDataAndUploadFile(@RequestPart("uploadFile") MultiPartFile uploadFile,
                                    @RequestParam("josnData") String jsonData) {
    StringBuilder sb = new StringBuilder();
    sb.append(uploadFile.getOriginalFilename()).append(";;;"));
    return person.toString() + ":::" + sb.toString();
}

参考：
https://blog.csdn.net/mynoteblog/article/details/126973322

https://blog.csdn.net/chihaihai/article/details/115416076

https://blog.csdn.net/jcc4261/article/details/127744034

https://blog.csdn.net/qq_40104261/article/details/128674498

https://blog.csdn.net/u012894692/article/details/115875674