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opengoofy / crane4j

一个简单易用的关联字段填充框架，通过简单的注解配置快速根据外键/编码值填充相关字段，支持字典，枚举，方法等多种数据源。 A simple and easy-to-use data mapping framework, quickly populate relevant fields according to foreign keys/encoded values through simple annotation configuration, supports dictionaries, enumerations, methods and other data sources.
http://www.crane4j.cn
Apache License 2.0
218 stars 33 forks source link

在启动类添加 `@EnableCrane4j` 注解后，启动应用报错 “No ServletContext set” #126

Closed Createsequence closed 8 months ago

Createsequence commented 1 year ago

springboot 版本为 2.2.13.RELEASE，在启动类添加 @EnableCrane4j 注解后，启动应用报错：

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
19:09:57.511 ERROR [main] [] [TID: N/A] org.springframework.boot.SpringApplication 826 reportFailure - Application run failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'resourceHandlerMapping' defined in class path resource [cn/net/nova/component/config/WebMvcConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception; nested exception is java.lang.IllegalStateException: No ServletContext set
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:657) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:637) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1336) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1176) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:897) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879) ~[spring-context-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.13.RELEASE.jar:2.2.13.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.13.RELEASE.jar:2.2.13.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:405) [spring-boot-2.2.13.RELEASE.jar:2.2.13.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.13.RELEASE.jar:2.2.13.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.13.RELEASE.jar:2.2.13.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.13.RELEASE.jar:2.2.13.RELEASE]
    at cn.net.nova.self.MbossSelfServiceApplication.main(MbossSelfServiceApplication.java:40) [classes/:?]
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.web.servlet.HandlerMapping]: Factory method 'resourceHandlerMapping' threw exception; nested exception is java.lang.IllegalStateException: No ServletContext set
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:652) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    ... 19 more
Caused by: java.lang.IllegalStateException: No ServletContext set
    at org.springframework.util.Assert.state(Assert.java:76) ~[spring-core-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport.resourceHandlerMapping(WebMvcConfigurationSupport.java:534) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at cn.net.nova.component.config.WebMvcConfig$$EnhancerBySpringCGLIB$$cbf82e93.CGLIB$resourceHandlerMapping$23(<generated>) ~[mboss-component-1.0-20230619.070641-242.jar:?]
    at cn.net.nova.component.config.WebMvcConfig$$EnhancerBySpringCGLIB$$cbf82e93$$FastClassBySpringCGLIB$$c78f2e22.invoke(<generated>) ~[mboss-component-1.0-20230619.070641-242.jar:?]
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:331) ~[spring-context-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at cn.net.nova.component.config.WebMvcConfig$$EnhancerBySpringCGLIB$$cbf82e93.resourceHandlerMapping(<generated>) ~[mboss-component-1.0-20230619.070641-242.jar:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_92]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_92]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_92]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_92]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:652) ~[spring-beans-5.2.12.RELEASE.jar:5.2.12.RELEASE]
    ... 19 more

Disconnected from the target VM, address: '127.0.0.1:54353', transport: 'socket'

Process finished with exit code 1
Createsequence commented 1 year ago

根据排查，似乎是在通过 WebMvcConfigurationSupport#resourceHandlerMapping 创建 HandlerMapping 时，由于当前实例仍然没有 ServletContext 所以报错： image 其中，实例中的 ServletContext 来自于 ServletContextAware 回调接口的 setServletContext 方法，此时通过调试发现，用于在后处理阶段调用 ServletContextAware 回调接口的后处理器 ServletContextAwareProcessor 在容器中并不存在： image 由于未经过后处理器的处理，因此该 WebMvcConfigurationSupport 实例并没有获得 ServletContext ，然后创建 HandlerMapping 由于 ServletContext 为空所以直接报错了。

Createsequence commented 1 year ago

经过试验，不再直接通过 @EnableCrane4j 引入配置，而是直接引入 Crane4jAutoConfiguration 配置类即可：

/**
 * 在项目里面另外建一个配置类继承 Crane4jAutoConfiguration
 * 
 * @author huangchengxing
 */
@Configuration
public class Crane4jConfig extends Crane4jAutoConfiguration {
}

不过具体原因还需要进一步排查，怀疑是 crane4j-spring-boot-starter 中引入的 springboot 依赖中自带了部分自动配置类，导致依赖或配置冲突。

Createsequence commented 9 months ago

经过验证，也可以在自己的项目中的 META-INF 文件夹下通过 SPI 文件引入 crane4j 配置类，这种方式也不会报错：

  1. 在 springboot 2.7 及以上版本，你需要在 spirng 文件夹下提供一个 org.springframework.boot.autoconfigure.AutoConfiguration.imports 文件，里面内容如下：

    cn.crane4j.spring.boot.config.Crane4jAutoConfiguration
cn.crane4j.spring.boot.config.Crane4jJacksonConfiguration
cn.crane4j.spring.boot.config.Crane4jMybatisPlusAutoConfiguration

  2. 在 springboot 2.7 以下版本，你需要提供一个 spring.factories 文件，里面内容如下：

    org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  cn.crane4j.spring.boot.config.Crane4jAutoConfiguration,\
  cn.crane4j.spring.boot.config.Crane4jJacksonConfiguration,\
  cn.crane4j.spring.boot.config.Crane4jMybatisPlusAutoConfiguration
Createsequence commented 9 months ago

2.4.0 版本这个问题仍然还未解决，经过研究，发现了问题确实是因为配置的加载顺序导致的，不过并不是之前说的 ServletContextAwareProcessor 不存在（实际上生效的是它的子类 WebApplicationContextServletContextAwareProcessor），而是 ServletContextAwareProcessor 生效时并没有获取到 ServletContext。

首先，Crane4jAutoConfiguration 这个配置类里面有一个 BeanMethodContainerPostProcessor，它是一个 BeanPostProcessor 类型的 Bean，用来将方法适配为方法容器，在容器启动时，它会在 registerBeanPostProcessors 这一步提前将其初始化。

然而， BeanMethodContainerPostProcessor 依赖了非常多的上级组件，这导致它们会跟着该后处理器一并发生初始化，这个依赖链最后导致提前触发了 WebMvcAutoConfiguration 的初始化：

EnableWebMvcConfiguration 实现了 ServletContextAware 接口，当它加载时，ServletContextAwareProcessor 这个后处理器依然获取不到 ServletContext，因此 EnableWebMvcConfiguration 也不能通过回调接口得到 ServletContextAware。

再往后，当容器加载所有单例 Bean 时，将会根据 EnableWebMvcConfiguration.resourceHandlerMapping 工厂方法创建 HandlerMapping，此时它将会尝试获取 EnableWebMvcConfiguration 中通过 ServletContextAware 回调注入的 ServletContext，然而由于该配置类并没有获得 ServletContext，因此就会报错 “No ServletContext set”。

SpringBoot 在 Web 环境的启动这一块我不是很熟，但是根据目前的观察，将 Crane4j 的配置类延迟加载可以解决这个问题，比如将注解加载项目的配置类上，或者将令本地的配置类继承 Crane4j 的配置类。

不过，这个问题也反映了通过 BeanPostProcessor 实现将方法适配为容器的功能并不合理，它会导致在自动装配时，仅仅为了加载这么一个 Bean 就让非常多的关联组件被提前加载。在下一个 2.5.0 版本，将会重构它，参照 Spring 的 EventListenerProcessor，改为基于 SmartInitializingSingleton 实现。