当包从hello更改为foo时，NoSuchBeanDefinitionException。

Question

当我按照https://spring.io/guides/gs/spring-boot/上提供的说明操作时，我可以使Spring Boot示例程序成功运行。

如果我将HelloService和HelloServiceImpl（如下所示的代码）添加到hello包中，并将HelloController.java更改为调用sayHello方法，那么它将按照预期工作，并且从http://localhost:8080中，我将看到如下所示的消息，正如预期的那样。

春靴的问候！helloService=来自HelloServiceImpl的Hello

现在，如果我将HelloService和HelloServiceImpl移动到foo包，那么在运行它时进行编译后，我得到如下所示的错误。

为什么spring Boot/Framework不能从“foo”包中获取所需的bean？但是，我能够验证它能够从hello包中成功地获取bean。

谢谢,

卡特彼勒HelloService.java

package hello;

public interface HelloService {

    public String sayHello();   

}

卡特彼勒HelloServiceImpl.java

package hello;
import org.springframework.stereotype.Service;


@Service("helloService")
public class HelloServiceImpl implements HelloService {

    /* (non-Javadoc)
     * @see com.apress.prospring3.springblog.service.HelloService#sayHello()
     */
    @Override
    public String sayHello() {
        return "Hello  from HelloServiceImpl ";
    }

}

在hellocontroller.java中，在index方法中更改return语句，如下所示，以便调用hello服务。

卡特彼勒HelloController.java

package hello;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class HelloController {

    @Autowired 
    private HelloService helloService;

    @RequestMapping("/")
    public String index() {
        return "Greetings from Spring Boot! helloService = " + helloService.sayHello();
    }
}

$java-版本

java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)

$which java

/usr/bin/java

lrwxr-xr-x 1 root wheel 74 3月9日22:00/usr/bin/java->/system/library/frameworks/javavm.framework/versions/current/commands/java

如果我将helloservice.java和helloserviceimpl.java从hello包移动到foo包，并且没有其他更改，那么当我尝试运行它时会得到以下错误。为什么它不能从'foo'包拾取，而它可以成功地从hello包拾取？如何解决此问题？这是否意味着这两个类必须驻留在hello包中才能工作？

Thx,

java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
    at java.lang.Thread.run(Thread.java:744)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private foo.HelloService hello.HelloController.helloService; nested exception is org.springframework.beans.factory.**NoSuchBeanDefinitionException**: No qualifying bean of type [foo.HelloService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1180)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:296)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:660)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:552)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:293)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:749)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:738)
    at hello.Application.main(Application.java:17)
    ... 6 more

原因：org.SpringFramework.Beans.Factory.BeanCreationException：无法自动连接字段：private Foo.HelloService Hello.HelloController.HelloService；嵌套异常为org.springframework.beans.factory.noSuchBeanDefinitionException：未找到依赖项得[foo.helloservice]类型得合格bean：需要至少一个具有此依赖项自动候选资格得bean.依赖项批注：{@org.springframework.beans.factor.annotation.AutoWired(required=true)}（位于org.springframework.beans.factor.annotation.AutoWiredanNotationbeanpostprocessor.java:508)（位于org.springframework.beans.factor.annotation.injectionmetadata.inject（injectionmetadata.java:87)（位于依赖关系批注：{@org.springframework.beans.factory.annotation.AutoWired(required=true)}（位于org.springframework.beans.factory.support.defaultlistablebeanfactory.raisenosuchbeandefinitionexception（defaultlistablebeanfactory.1060)（位于

Answer 1

最初，当HelloService在hello包中时，Configuration类上的@ComponentScan告诉Spring在hello包中查找其他组件、配置和服务，从而允许它查找该类。现在由于您已经将HelloService移动到foo包中，@ComponentScan再也找不到它了；您还需要指定新的包名称，如：

    @ComponentScan({"hello","foo"})