Java SpringBoot整合shiro-spring-boot-starterqi项目报错解决

1、项目启动时报错如下

Description:
The bean 'securityManager', defined in class path resource [org/apache/shiro/spring/config/web/autoconfigure/ShiroWebAutoConfiguration.class], could not be registered. A bean with that name has already been defined in class path resource [com/ncwu/common/infrastructure/config/ShiroConfig.class] and overriding is disabled.
Action:
Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

2、原因分析

我的自定义ShiroConfig配置类中添加的安全管理器,

代码如下:

@Bean
public SecurityManager securityManager(JwtRealm jwtRealm) {
    DefaultWebSecurityManager securityManager = new DefaultWebSecurityManager();
    //配置realm
    securityManager.setRealm(jwtRealm);
    return securityManager;
}

 根据异常信息查看ShiroWebAutoConfiguration源码时发现其中已经定义了securityManager方法,我们在ShiroConfig配置类中再次定义securityManager方法,因返回的类与其不一样导致出错,

ShiroWebAutoConfiguration类中定义的securityManager方法代码如下:

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

下面这些为补充知识:我们都知道@ConditionalOnBean作用是根据value属性按bean的类型或则bean的名称判断bean是否在IOC容器中,如果在就返回true,否则返回false。而@ConditionalOnMissingBean的作用与@ConditionalOnBean相反。如果@ConditionalOnBean和@ConditionalOnMissingBean这两个注解没有参数,那这两个注解以何种方式来判断呢?在Spring Boot官方文档中找出了答案。

Java SpringBoot整合shiro-spring-boot-starterqi项目报错解决_第1张图片

意思是:在@ConditionalOnMissingBean没有参数的情况下,目标类型默认为方法的返回类型,如果IOC容器中没有类型为MyService及其子类的Bean,那么myServiceBean将被创建。

从源代码中可以看出@ConditionalOnMissingBean没有参数,那么如果IOC容器中没有类型为SessionsSecurityManager及其子类的Bean,那么该方法则会执行,并且源码securityManager方法返回的是SessionsSecurityManager,而自己定义的ShiroConfig中返回的是SecurityManager(因为@Bean注解会指定改bean的类型为该方法的返回类型),所以它会判断出IOC容器中没有类型为SessionsSecurityManager及其子类的Bean,源码中的方法执行,故IOC容器中有两个名为securityManager的Bean,因而报错。所以如果要自定义securityManager方法,返回类型只能是SessionsSecurityManager及其子类,而SessionsSecurityManager的子类是DefaultSecurityManager,DefaultWebSecurityManager又继承DefaultSecurityManager,

相关类图如下:

Java SpringBoot整合shiro-spring-boot-starterqi项目报错解决_第2张图片

故而正确的代码应该是:

@Bean
public SessionsSecurityManager securityManager(JwtRealm jwtRealm) {
    DefaultWebSecurityManager securityManager = new DefaultWebSecurityManager();
    //配置realm
    securityManager.setRealm(jwtRealm);
    return securityManager;
}
 
//或者如下,将方法返回类型改为DefaultWebSecurityManager 
/*@Bean
public DefaultWebSecurityManager securityManager(JwtRealm jwtRealm) {
    DefaultWebSecurityManager securityManager = new DefaultWebSecurityManager();
    //配置realm
    securityManager.setRealm(jwtRealm);
    return securityManager;
}*/

3、测试@ConditionalOnMissingBean注解

新建下面3个类:

//动物
@Data
public class Animal {
    private String name;
    private Integer age;
}

//狗
@EqualsAndHashCode(callSuper = true)
@Data
public class Dog extends Animal {
    private String type;
}
 
//二哈
@EqualsAndHashCode(callSuper = true)
@Data
public class TwoHa extends Dog {
    private String a;
}

启动类:

@SpringBootApplication
//扫描下面的接口生成代理实现类
@MapperScan("com.ncwu.**.domain.mapper")
public class ShiroApplication {
    public static void main(String[] args) {
        SpringApplication.run(ShiroApplication.class, args);
    }

    //若IOC容器中没有Animal类型及其子类Dog类型的bean时,该方法才会执行
    @Bean
    @ConditionalOnMissingBean
    public Animal twoHa(JwtRealm realm) {
        TwoHa twoHa = new TwoHa();
        twoHa.setType("twoHa1");
        twoHa.setAge(10);
        twoHa.setName("twoHa1");
        return twoHa;
    }

    @Bean
    public Dog twoHa() {
        TwoHa twoHa = new TwoHa();
        twoHa.setType("twoHa2");
        twoHa.setAge(20);
        twoHa.setName("twoHa2");
        return twoHa;
    }
}

测试类:

@RunWith(SpringRunner.class)
@SpringBootTest(classes = ShiroApplication.class)
public class TestDao {
    @Autowired
    private ApplicationContext appContext;
    @Test
    public void test() throws Exception{
        /*String[] beanNamesForType = appContext.getBeanNamesForType(Animal.class);
        for (String s : beanNamesForType) {
            System.out.println(s);
        }*/
        appContext.getBean(Animal.class);
        //appContext.getBean("dog");
    }
}

测试结果:

Java SpringBoot整合shiro-spring-boot-starterqi项目报错解决_第3张图片

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