Java IllegalStateException - @ComponentScanning 一个 springframework 包

IllegalStateException - @ComponentScanning a springframework package

提问by Adam Harrison

I've been working through the following tutorial:

我一直在学习以下教程：

http://spring.io/guides/gs/rest-service/

http://spring.io/guides/gs/rest-service/

I was initially able to get the code to work correctly (Run the finished tutorial, send an HTTP message and get the correct response) and successfully expand upon it.

我最初能够使代码正常工作（运行完成的教程，发送 HTTP 消息并获得正确的响应）并成功扩展它。

After expanding further, I ran into the following exception:

进一步扩展后，我遇到了以下异常：

java.lang.IllegalStateException: Could not evaluate condition on org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration#propertySourcesPlaceholderConfigurer due to internal class not found. This can happen if you are @ComponentScanning a springframework package (e.g. if you put a @ComponentScan in the default package by mistake)
    at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:51)
    at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:92)
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForBeanMethod(ConfigurationClassBeanDefinitionReader.java:174)
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:136)
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:116)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:330)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:243)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:254)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:94)
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:611)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:961)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:950)
    at com.aharrison.hello.Application.main(Application.java:15)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

I've since stripped the code back down to only what is shown in the example, but I am still experiencing the exception.

从那以后，我将代码剥离回仅示例中显示的内容，但我仍然遇到异常。

I think it could possibly be related to the following issue, although it is marked as closed:

我认为它可能与以下问题有关，尽管它被标记为已关闭：

https://github.com/spring-projects/spring-boot/issues/2050

https://github.com/spring-projects/spring-boot/issues/2050

I'm not very experienced with Spring, so I can't fully comprehend what is being discussed.

我对 Spring 不是很有经验，所以我不能完全理解正在讨论的内容。

Here are my current classes:

这是我目前的课程：

Greeting.java:

问候.java：

package com.aharrison.hello;

public class Greeting {
    private final long id;
    private final String content;

    public Greeting(long id, String content) {
        this.id = id;
        this.content = content;
    }

    public long getId() {
        return id;
    }

    public String getContent() {
        return content;
    }
}

GreetingController:

问候控制器：

package com.aharrison.hello;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.atomic.AtomicLong;

@RestController
public class GreetingController {
    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @RequestMapping("/greeting")
    public Greeting greeting(@RequestParam(value="name", defaultValue="World") String name) {
        return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }
}

Application.java :

应用程序.java :

package com.aharrison.hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.ComponentScan;

/**
 * Created by Adam on 12/26/2014.
 */
@ComponentScan
@EnableAutoConfiguration
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

pom.xml:

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.aharrison</groupId>
<artifactId>SpringRestAPI</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <version>1.2.0.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>4.1.3.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-mongodb</artifactId>
        <version>1.6.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.mongodb</groupId>
        <artifactId>mongo-java-driver</artifactId>
        <version>2.12.2</version>
    </dependency>
</dependencies>

Questions:

问题：

1. What is causing the exception in this situation? Is there something wrong with my code above, or is the problem environment related?
2. When the exception says "..if you put a @ComponentScan in the default package by mistake", which is the default package it is referring to? Is this applicable to the current situation?

1. 在这种情况下导致异常的原因是什么？是我上面的代码有问题，还是和问题环境有关？
2. 当异常显示“..如果您错误地将@ComponentScan 放入默认包中”时，它指的是哪个默认包？这适用于目前的情况吗？

Thanks in advance.

提前致谢。

回答by wassgren

When I run the code that you have provided everything works fine. The only change I had to make was in the pom.xmlwhere I added the following:

当我运行您提供的代码时，一切正常。我必须做的唯一更改是在pom.xml我添加以下内容的地方：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.2.0.RELEASE</version>
</parent>

This enables the whole Spring Bootmechanism and is required in order for you to be able to start the application.

这启用了整个Spring Boot机制，并且是您启动应用程序所必需的。

See below for the successful output from my test run:

请参阅下面的测试运行的成功输出：

  .   ____          _            __ _ _
 /\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.2.0.RELEASE)

2014-12-27 17:41:12.472  INFO 4065 --- [           main] com.aharrison.hello.Application          : Starting Application on My-MacBook-Pro.local with PID 4065 (/Users/wassgren/test/target/test-classes started by wassgren in /Users/wassgren/test/test-di)
2014-12-27 17:41:12.506  INFO 4065 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4a668b6e: startup date [Sat Dec 27 17:41:12 CET 2014]; root of context hierarchy
2014-12-27 17:41:13.407  INFO 4065 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Overriding bean definition for bean 'beanNameViewResolver': replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
2014-12-27 17:41:14.186  INFO 4065 --- [           main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration' of type [class org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2014-12-27 17:41:14.703  INFO 4065 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080/http
2014-12-27 17:41:15.047  INFO 4065 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2014-12-27 17:41:15.048  INFO 4065 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.0.15
2014-12-27 17:41:15.154  INFO 4065 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2014-12-27 17:41:15.154  INFO 4065 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2651 ms
2014-12-27 17:41:16.399  INFO 4065 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean        : Mapping servlet: 'dispatcherServlet' to [/]
2014-12-27 17:41:16.404  INFO 4065 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2014-12-27 17:41:16.404  INFO 4065 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'characterEncodingFilter' to: [/*]
2014-12-27 17:41:16.907  INFO 4065 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4a668b6e: startup date [Sat Dec 27 17:41:12 CET 2014]; root of context hierarchy
2014-12-27 17:41:16.979  INFO 4065 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/greeting],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public com.aharrison.hello.Greeting com.aharrison.hello.GreetingController.greeting(java.lang.String)
2014-12-27 17:41:16.981  INFO 4065 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2014-12-27 17:41:16.981  INFO 4065 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],methods=[],params=[],headers=[],consumes=[],produces=[text/html],custom=[]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest)
2014-12-27 17:41:17.013  INFO 4065 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2014-12-27 17:41:17.014  INFO 4065 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2014-12-27 17:41:17.059  INFO 4065 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2014-12-27 17:41:17.206  INFO 4065 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2014-12-27 17:41:17.292  INFO 4065 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080/http
2014-12-27 17:41:17.294  INFO 4065 --- [           main] com.aharrison.hello.Application          : Started Application in 5.245 seconds (JVM running for 6.088)

回答by Vikram Palakurthi

Spring Boot 1.2.2 is released, I would advice to upgrade to the new version as it comes with a significant number of fixes. Also it uses the spring-security 3.2.6. You would have to be very careful when you declare any or override dependencies other than the ones that come by default, as the boot already comes with most of it. I had the same problem with using the spring boot 1.2.2 with spring security 3.2.5 but when i rolled back to spring boot 1.2.1 everything was fine.

Spring Boot 1.2.2 已发布，我建议升级到新版本，因为它带有大量修复。它也使用 spring-security 3.2.6。当您声明任何或覆盖默认情况下的依赖项之外的任何依赖项时，您必须非常小心，因为引导已经附带了大部分依赖项。我在使用 spring boot 1.2.2 和 spring security 3.2.5 时遇到了同样的问题，但是当我回滚到 spring boot 1.2.1 时，一切都很好。

回答by Maria

Remove the @ComponentScan which is placed above the Application class. @SpringBootApplication adds it by default, if the classes you need to be scanned are within the same package as the Application class.

删除位于 Application 类上方的 @ComponentScan。@SpringBootApplication默认添加，如果你需要扫描的类和Application类在同一个包内。

回答by DareDevil

Placing @SpringBootApplication annotation on the application class and placing the application class in the same package or the parent package of the called classes will fix the issue.

在应用程序类上放置@SpringBootApplication 注解并将应用程序类放置在同一个包或被调用类的父包中将解决此问题。