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Shiro踩坑记(一):关于shiro-spring-boot-web-starter自动注解无法注入authorizer的问题

作者:互联网

一)问题描述:

我在一个Spring的项目中使用shiro搭建权限控制框架。主要通过shiro-spring-boot-web-starter包快速集成Shiro。但是项目无法启动,报没有authorizer的bean的错误:
```
No bean named 'authorizer' available
```  
我只好又在自己的Configuration中又配置了Authorizer,才能正常启动。  

@Configuration
public class ShiroConfig {

@Bean
public Authorizer authorizer(){
    return new ModularRealmAuthorizer();
}
}

但是奇怪的明明athorizer是SecurityManager中一个重要的组件,为什么没有在shiro starter的Configuration中被声明为Bean?同样的,Authenticator就没问题?

二)明确shiro-spring-boot-web-starter是否有对应的声明

我们在pom文件中声明了shiro-spring-boot-web-starter。就从对应的jar包开始找起。
首先是META-INF中的spring.factories文件。我们知道spring-boot-starter都是通过在该文件中声明Configuraion来达到集成自身配置的目的。
```
org.springframework.boot.autoconfigure.EnableAutoConfiguration = org.apache.shiro.spring.config.web.autoconfigure.ShiroWebAutoConfiguration, org.apache.shiro.spring.config.web.autoconfigure.ShiroWebFilterConfiguration

上述声明了两个Configration:ShiroWebAutoConfiguration和ShiroWebFilterConfiguration。  
-    ShiroWebFilterConfiguration
先从简单的配置说起,ShiroWebFilterConfiguration是以添加Filter的方式来达到authentication的目的。这个和我们的问题无关,简单带过。
-    ShiroWebAutoConfiguration  

@Configuration
@AutoConfigureBefore(ShiroAutoConfiguration.class)
@ConditionalOnProperty(name = "shiro.web.enabled", matchIfMissing = true)
public class ShiroWebAutoConfiguration extends AbstractShiroWebConfiguration {

@Bean
@ConditionalOnMissingBean
@Override
protected AuthenticationStrategy authenticationStrategy() {
    return super.authenticationStrategy();
}

@Bean
@ConditionalOnMissingBean
@Override
protected Authenticator authenticator() {
    return super.authenticator();
}

@Bean
@ConditionalOnMissingBean
@Override
protected Authorizer authorizer() {
    return super.authorizer();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SubjectDAO subjectDAO() {
    return super.subjectDAO();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionStorageEvaluator sessionStorageEvaluator() {
    return super.sessionStorageEvaluator();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SubjectFactory subjectFactory() {
    return super.subjectFactory();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionFactory sessionFactory() {
    return super.sessionFactory();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionDAO sessionDAO() {
    return super.sessionDAO();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionManager sessionManager() {
    return super.sessionManager();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionsSecurityManager securityManager(List<Realm> realms) {
    return createSecurityManager();
}

@Bean
@ConditionalOnMissingBean(name = "sessionCookieTemplate")
@Override
protected Cookie sessionCookieTemplate() {
    return super.sessionCookieTemplate();
}

@Bean
@ConditionalOnMissingBean
@Override
protected RememberMeManager rememberMeManager() {
    return super.rememberMeManager();
}

@Bean
@ConditionalOnMissingBean(name = "rememberMeCookieTemplate")
@Override
protected Cookie rememberMeCookieTemplate() {
    return super.rememberMeCookieTemplate();
}

@Bean
@ConditionalOnMissingBean
@Override
protected ShiroFilterChainDefinition shiroFilterChainDefinition() {
    return super.shiroFilterChainDefinition();
}

}


这个配置类将Shiro需要的各组件都声明成了bean,交给容器管理。具体的创建过程都在父类AbstractShiroWebConfiguration。可以看到确实是有声明authorizer。但是为什么会找不到呢?是不是其他的配置文件声明了类似的bean,产生了影响?

#### 三)继续查找其他配置
观察shiro-spring-boot-web-starter的配置文件,可以看到它又引用了shiro-spring-boot-starter包。shrio-spring-boot-starter又是一个Spring boot starter包,同样通过它的META-INF文件,可以知道加入了哪些Configuration:  

org.springframework.boot.autoconfigure.EnableAutoConfiguration = org.apache.shiro.spring.boot.autoconfigure.ShiroBeanAutoConfiguration, org.apache.shiro.spring.boot.autoconfigure.ShiroAutoConfiguration, org.apache.shiro.spring.boot.autoconfigure.ShiroAnnotationProcessorAutoConfiguration

org.springframework.boot.diagnostics.FailureAnalyzer = org.apache.shiro.spring.boot.autoconfigure.ShiroNoRealmConfiguredFailureAnalyzer


最后一个文件是判断项目中不存在Realm时,抛出异常。前面是我们需要关注的配置文件。
- ShiroAnnotationProcessorAutoConfiguration  
该配置主要是通过AOP的方式实现authorization的功能。
- ShiroBeanAutoConfiguraion  
主要是通过添加BeanPostProcessor,在Shiro相关的Bean初始化时,做一些额外的操作。  
- ShiroAutoConfiguration    

@Configuration
@SuppressWarnings("SpringFacetCodeInspection")
@ConditionalOnProperty(name = "shiro.enabled", matchIfMissing = true)
public class ShiroAutoConfiguration extends AbstractShiroConfiguration {

@Bean
@ConditionalOnMissingBean
@Override
protected AuthenticationStrategy authenticationStrategy() {
    return super.authenticationStrategy();
}

@Bean
@ConditionalOnMissingBean
@Override
protected Authenticator authenticator() {
    return super.authenticator();
}

@Bean
@ConditionalOnMissingBean
@Override
protected Authorizer authorizer() {
    return super.authorizer();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SubjectDAO subjectDAO() {
    return super.subjectDAO();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionStorageEvaluator sessionStorageEvaluator() {
    return super.sessionStorageEvaluator();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SubjectFactory subjectFactory() {
    return super.subjectFactory();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionFactory sessionFactory() {
    return super.sessionFactory();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionDAO sessionDAO() {
    return super.sessionDAO();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionManager sessionManager() {
    return super.sessionManager();
}

@Bean
@ConditionalOnMissingBean
@Override
protected SessionsSecurityManager securityManager(List<Realm> realms) {
    return super.securityManager(realms);
}

@Bean
@ConditionalOnResource(resources = "classpath:shiro.ini")
protected Realm iniClasspathRealm() {
    return iniRealmFromLocation("classpath:shiro.ini");
}

@Bean
@ConditionalOnResource(resources = "classpath:META-INF/shiro.ini")
protected Realm iniMetaInfClasspathRealm() {
    return iniRealmFromLocation("classpath:META-INF/shiro.ini");
}

@Bean
@ConditionalOnMissingBean(Realm.class)
protected Realm missingRealm() {
    throw new NoRealmBeanConfiguredException();
}

}


大致内容其实和ShiroWebAutoConfiguration很类似,只是ShiroWebAutoConfiguration将一些组件替换成了WEB环境相关的组件。但是ShiroWebAutoConfiguration声明了它的配置要在ShiroAutoConfiguration之前,而且根据ConditionalOnMissingBean的条件,得出Bean的配置应该是以ShiroWebAutoConfiguration中声明的为准。但是死马当活马医,配置文件中添加shiro.enabled为false的条件,再试试。。。果然还是不行。  

#### 四)DEBUG大法好
毫无办法的办法就是DEBUG大法。
首先从Configuration中生命的Bean是如何被容器加载的过程入手,找到了ConfigurationClassPostProcessor。同样是一个PostProcessor,猜想应该是在configuration bean的后置处理中进行了@Bean方法的解析。
主要的处理过程在processConfigBeanDefinition这个方法中,对这个方法做个简单的说明  

/**
* Build and validate a configuration model based on the registry of
* {@link Configuration} classes.
*/
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List configCandidates = new ArrayList<>();
//获取registry中的bean definition
String[] candidateNames = registry.getBeanDefinitionNames();

    for (String beanName : candidateNames) {
        BeanDefinition beanDef = registry.getBeanDefinition(beanName);
        //bean definition 有configuration的属性,说明已经被解析处理过
        if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
                ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
            }
        }
        //判断是否是configuration的bean,是则加入候选
        else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
            configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
        }
    }

    // 如果没有发现候选者,则返回
    if (configCandidates.isEmpty()) {
        return;
    }

    // 排序
    configCandidates.sort((bd1, bd2) -> {
        int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
        int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
        return Integer.compare(i1, i2);
    });

    // Detect any custom bean name generation strategy supplied through the enclosing application context
    SingletonBeanRegistry sbr = null;
    if (registry instanceof SingletonBeanRegistry) {
        sbr = (SingletonBeanRegistry) registry;
        if (!this.localBeanNameGeneratorSet) {
            BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
            if (generator != null) {
                this.componentScanBeanNameGenerator = generator;
                this.importBeanNameGenerator = generator;
            }
        }
    }

    if (this.environment == null) {
        this.environment = new StandardEnvironment();
    }

    // 开始解析configuration 的bean definition
    ConfigurationClassParser parser = new ConfigurationClassParser(
            this.metadataReaderFactory, this.problemReporter, this.environment,
            this.resourceLoader, this.componentScanBeanNameGenerator, registry);

    Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
    Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());

    // 如果候选者不为空,则继续解析
    do {
        // 解析过程
        parser.parse(candidates);
        // 校验
        parser.validate();

        // 获取新解析的config class   
        Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses());
        // 移除掉已经解析过的部分
        configClasses.removeAll(alreadyParsed);

        // 创建reader,添加bean definition
        if (this.reader == null) {
            this.reader = new ConfigurationClassBeanDefinitionReader(
                    registry, this.sourceExtractor, this.resourceLoader, this.environment,
                    this.importBeanNameGenerator, parser.getImportRegistry());
        }
        this.reader.loadBeanDefinitions(configClasses);
        alreadyParsed.addAll(configClasses);

        candidates.clear();
        //如果bean definition数量 大于 候选者的数量,说明有新的bean加入
        if (registry.getBeanDefinitionCount() > candidateNames.length) {
            String[] newCandidateNames = registry.getBeanDefinitionNames();
            Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));

            Set<String> alreadyParsedClasses = new HashSet<>();

            for (ConfigurationClass configurationClass : alreadyParsed) {
                alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
            }

            for (String candidateName : newCandidateNames) {
                //不在旧的candidate中,说明是新加入的
                if (!oldCandidateNames.contains(candidateName)) {

                    BeanDefinition bd = registry.getBeanDefinition(candidateName);
                    //未被解析的config class,添加到candidates中,等下一轮解析
                    if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
                            !alreadyParsedClasses.contains(bd.getBeanClassName())) {
                        candidates.add(new BeanDefinitionHolder(bd, candidateName));
                    }
                }
            }
            //更新候选者
            candidateNames = newCandidateNames;
        }
    }
    while (!candidates.isEmpty());

    // Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
    if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
        sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
    }

    if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
        // Clear cache in externally provided MetadataReaderFactory; this is a no-op
        // for a shared cache since it'll be cleared by the ApplicationContext.
        ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
    }
}

1)parser.parse后设置断点,看ConfigurationClassParser是否能将ShiroWebAutoConfiguration中的@Bean正常的解析:  


![1](https://www.icode9.com/i/l/?n=18&i=blog/887326/201906/887326-20190615173536095-1495318162.jpg)


可以看到authorizer确实已经被ShiroWebAutoConfiguration加载。  

2)解析没问题,那就看加载是否成功:
继续往下走,看reader.loadBeanDefinitions发生了什么:  
![2](https://www.icode9.com/i/l/?n=18&i=blog/887326/201906/887326-20190615173826413-929864045.jpg)


找出ShiroWebAutoConfiguration对应的ConfigurationClass,看到SkippedBeanMethods中有authorizer!!!也就是说虽然解析出了authorizer,但是在加载的时候却被选择跳过了。。。  
3)问题就变得比较清晰了,找出为什么被跳过的原因。  
顺着代码找到ConfigurationClassBeanDefinitionReader的loadBeanDefinitionsForConfigurationClass的方法,负责处理的BeanMethond的过程是在loadBeanDefitionsForBeanMethod中。  
确实在方法开始前,有一个判断是否需要跳过的条件:  

if (this.conditionEvaluator.shouldSkip(metadata, ConfigurationPhase.REGISTER_BEAN)) {
configClass.skippedBeanMethods.add(methodName);
return;
}


shouldSkip这个方法是根据@Bean上的@Conditional注解,来判断是否需要加载该Bean。回忆上文我们的ShiroWebAutoConfiguration中,确实在authorizer的方法上有@ConditionalOnMissingBean的注解。也就是说应该是哪里声明authorizer的Bean,导致配置中的Bean没有被加载。  
4)OnBeanCondition.getMatchOutcome():处理@Bean的@Condtional条件,并输出结果。  

![3](https://www.icode9.com/i/l/?n=18&i=blog/887326/201906/887326-20190615173856133-1178000804.jpg)


最后发现被跳过的原因竟然是:  

found beans of type 'org.apache.shiro.authz.Authorizer' authorizer, thirdPartyRealm, userRealm


我自定义的Realm竟然和authorizer冲突了。Spring认为已经有authorizer的bean,而不再加载配置中的authorizer。  
5)为什么Realm和authorizer冲突?原来在获取相匹配的Bean时候还是通过容器本身(BeanFactory)的getNamesForType方法:  
Set<String> getNamesForType(Class<?> type) {
    updateTypesIfNecessary();
    //便利容器中所有的bean类型,将类型匹配的Type全部返回。注意这里还用了isAssiginableFrom,因此这里的查询类型的子类也会满足
    return this.beanTypes.entrySet().stream()
            .filter((entry) -> entry.getValue() != null
                    && type.isAssignableFrom(entry.getValue()))
            .map(Map.Entry::getKey)
            .collect(Collectors.toCollection(LinkedHashSet::new));
}

```

反观我们的Realm对象:AuthorizingRealm实现了Authorizer接口。真相大白。

标签:坑记,authorizer,return,web,Bean,protected,ConditionalOnMissingBean,Override,super
来源: https://www.cnblogs.com/insaneXs/p/11028286.html