Springboot开发常见问题总结

本文会持续不定时更新

1.配置静态资源路径

spring.resources.static-locations=classpath:/templates/,classpath:/static/

特别注意：路径最后的"/"千万不能少了，否则该条配置就失效了。

错误的路径：classpath:/templates

正确的路径：classpath:/templates/

2.返回的视图名不能与访问路径相同

@RequestMapping("index")
public String hello(){
    return "/index.html";
}

注:当访问 http://ip:port/index 时，将会产生异常，不能正常访问到index.html页面

3.springboot由1.x升级为2.x后JPA无法正常工作

    当升级为2.x后，系统无法正常启动，启动时会报错，错误信息如下

***************************
APPLICATION FAILED TO START
***************************

Description:

Field studentRepository in learn.jpa.rpc.MyController required a bean named 'entityManagerFactory' that could not be found.

Action:

Consider defining a bean named 'entityManagerFactory' in your configuration.

解决方案：在pom.xml中加入依赖即可完美解决，注意：千万不要去掉版本号，必须是5.x的版本才可以

	org.hibernate
	hibernate-core
	5.2.1.Final

4.执行mvn test时出现异常BeanCreationNotAllowedException 

org.springframework.beans.factory.BeanCreationNotAllowedException: Error creating bean with name 'eurekaAutoServiceRegistration': Singleton bean creation not allowed while singletons of this factory are in destruction (Do not request a bean from a BeanFactory in a destroy method implementation!)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:216) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1078) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.event.ApplicationListenerMethodAdapter.getTargetBean(ApplicationListenerMethodAdapter.java:283) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.event.ApplicationListenerMethodAdapter.doInvoke(ApplicationListenerMethodAdapter.java:253) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.event.ApplicationListenerMethodAdapter.processEvent(ApplicationListenerMethodAdapter.java:177) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.event.ApplicationListenerMethodAdapter.onApplicationEvent(ApplicationListenerMethodAdapter.java:140) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:167) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:393) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:399) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:347) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:991) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:958) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.cloud.context.named.NamedContextFactory.destroy(NamedContextFactory.java:76) [spring-cloud-context-1.2.3.RELEASE.jar:1.2.3.RELEASE]
	at org.springframework.beans.factory.support.DisposableBeanAdapter.destroy(DisposableBeanAdapter.java:272) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroyBean(DefaultSingletonBeanRegistry.java:578) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingleton(DefaultSingletonBeanRegistry.java:554) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingleton(DefaultListableBeanFactory.java:961) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingletons(DefaultSingletonBeanRegistry.java:523) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.destroySingletons(FactoryBeanRegistrySupport.java:230) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingletons(DefaultListableBeanFactory.java:968) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.destroyBeans(AbstractApplicationContext.java:1030) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1006) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:958) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
	at org.springframework.boot.actuate.endpoint.ShutdownEndpoint$1.run(ShutdownEndpoint.java:74) [spring-boot-actuator-1.5.6.RELEASE.jar:1.5.6.RELEASE]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131]

解决方案:增加一个BeanFactoryPostProcessor 

@Component
public class FeignBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        if (containsBeanDefinition(beanFactory, "feignContext", "eurekaAutoServiceRegistration")) {
            BeanDefinition bd = beanFactory.getBeanDefinition("feignContext");
            bd.setDependsOn("eurekaAutoServiceRegistration");
        }
    }
    
    private boolean containsBeanDefinition(ConfigurableListableBeanFactory beanFactory, String... beans) {
        return Arrays.stream(beans).allMatch(b -> beanFactory.containsBeanDefinition(b));
    }
}

4.执行mvn test时，hystrix一直超时，导致测试失败

解决方案:由于测试连接时，肯定是第一次请求，而Feign又是懒加载的，所以第一次特别容易超时，所以只需要将超时时间变长，避免触发fallback

hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 5000