Swagger介绍及Springboot整合Swagger避坑

Swagger简介

前后端分离

vue+Springboot
后端时代：前端之管理静态页面，html==>后端。模板引擎 JSP=>后端是主力

前后端分离时代：

• 后端：后端控制层、服务层、数据访问层【后端团队】
• 前端：前端控制层、视图层【前端团队】
• 前后端如何交互？==>API
• 前后端相对独立，松耦合
• 前后端甚至可以部署在不同的服务器上

产生一个问题：

• 前后端联调，前端人员和后端人员无法做到“及时协商，尽早解决”，最终导致问题集中爆发

解决方案：

• 首先指定schema，实时更新最新API，降低集成的风险；
• 早些年：指定word文档；
• 前后端分离：
  • 前端测试后端接口：postman
  • 后端提供接口，需要实时更新最新消息的消息及改动！

Swagger

• 号称世界上最流行的api框架
• Restful Api文档在线自动生成工具=>Api文档与Api定义同步更新
• 直接运行，可以在线测试Api接口
• 支持多种语言：（Java，Php……）

官网：https://swagger.io/

在项目中使用Swagger需要Springbox

• Swagger2
• ui

SpringBoot集成Swagger2

主要步骤：

• 新建一个springboot项目
• 导入依赖（避坑，注意版本问题，使用3.0.0报错，最后改成2.9.2版本）

   <dependency>
            <groupId>io.springfoxgroupId>
            <artifactId>springfox-swagger2artifactId>
            <version>2.9.2version>
        dependency>
        <dependency>
            <groupId>io.springfoxgroupId>
            <artifactId>springfox-swagger-uiartifactId>
            <version>2.9.2version>
        dependency>

• 新建配置类

@Configuration
@EnableWebMvc
@EnableSwagger2
public class SwaggerConfig implements WebMvcConfigurer /*extends WebMvcConfigurationSupport*/{
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("swagger-ui.html")
                .addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/");
    }

    //配置了Swagger的Docket的bean实例
    @Bean
    public Docket docket(){
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(apiInfo());
    }

    //配置Swagger信息=apiInfo
    private ApiInfo apiInfo(){
        return new ApiInfoBuilder()
                .title("新建Title")
                .build();
    }
}
//如果使用WebMvcConfigurationSupport @EnableWebMvc注解不需要

注：如果没有@EnableWebMvc注解会报以下错；使用3.0.0版本会报404错误

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.3.13.jar:5.3.13]
	at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_302]
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.13.jar:5.3.13]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.0.jar:2.6.0]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:730) [spring-boot-2.6.0.jar:2.6.0]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412) [spring-boot-2.6.0.jar:2.6.0]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:302) [spring-boot-2.6.0.jar:2.6.0]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301) [spring-boot-2.6.0.jar:2.6.0]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1290) [spring-boot-2.6.0.jar:2.6.0]
	at com.wanaei.SwaggerApplication.main(SwaggerApplication.java:10) [classes/:na]
Caused by: java.lang.NullPointerException: null
	at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:112) ~[springfox-spi-2.9.2.jar:null]
	at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:109) ~[springfox-spi-2.9.2.jar:null]
	at com.google.common.collect.ComparatorOrdering.compare(ComparatorOrdering.java:37) ~[guava-20.0.jar:na]
	at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:1.8.0_302]
	at java.util.TimSort.sort(TimSort.java:220) ~[na:1.8.0_302]
	at java.util.Arrays.sort(Arrays.java:1438) ~[na:1.8.0_302]
	at com.google.common.collect.Ordering.sortedCopy(Ordering.java:855) ~[guava-20.0.jar:na]
	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:57) ~[springfox-spring-web-2.9.2.jar:null]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:138) ~[springfox-spring-web-2.9.2.jar:null]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:135) ~[springfox-spring-web-2.9.2.jar:null]
	at com.google.common.collect.Iterators$7.transform(Iterators.java:750) ~[guava-20.0.jar:na]
	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47) ~[guava-20.0.jar:na]
	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47) ~[guava-20.0.jar:na]
	at com.google.common.collect.MultitransformedIterator.hasNext(MultitransformedIterator.java:52) ~[guava-20.0.jar:na]
	at com.google.common.collect.MultitransformedIterator.hasNext(MultitransformedIterator.java:50) ~[guava-20.0.jar:na]
	at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:249) ~[guava-20.0.jar:na]
	at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:209) ~[guava-20.0.jar:na]
	at com.google.common.collect.FluentIterable.toList(FluentIterable.java:614) ~[guava-20.0.jar:na]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.defaultContextBuilder(DocumentationPluginsBootstrapper.java:111) ~[springfox-spring-web-2.9.2.jar:null]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.buildContext(DocumentationPluginsBootstrapper.java:96) ~[springfox-spring-web-2.9.2.jar:null]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:167) ~[springfox-spring-web-2.9.2.jar:null]
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-5.3.13.jar:5.3.13]
	... 14 common frames omitted

• 运行 http://localhost:8080/swagger-ui.html#/