为什么Spring Boot没有找到一个@service bean试图执行autowiring？bean存在，但找不到

Question

1）我定义了一个服务。首先，我定义了一个名为OrderService的接口，如下所示：

package com.dgs.soc.service;

import java.util.List;

import com.dgs.soc.excelapi.dto.Order;

public interface OrderService {

    public List<Order> getOrdersList();

}

然后我定义了它的实现，目前是一个非常简单的名为OrderServiceImpl的实现：

package com.dgs.soc.service;

import java.util.ArrayList;
import java.util.List;
import org.springframework.stereotype.Service;
import com.dgs.soc.excelapi.dto.Order;
import com.dgs.soc.repository.OrderRepository;

@Service
public class OrderServiceImpl {

    public List<Order> getOrdersList() {
        List<Order> result = new ArrayList<Order>();

        return result;
    }

}

正如您所看到的，@Service注释注释了这个类。

package com.dgs.soc.excelapi.integration;

// IMPORTS LIST

@RunWith(SpringRunner.class)
@SpringBootTest(classes = { Application.class })
@WebAppConfiguration
@ActiveProfiles(profiles = { "no-liquibase" })
public class ExcelResourceIntegrationTest {

    @Autowired
    OrderServiceImpl orderService;

    @Test
    public void getOrdersListRepositoryTest() { 
        List<Order> ordersList = orderService.getOrdersList();
        assertThat(ordersList).isNotEmpty();
    }

}

2020-03-23 04:42:24.783 ERROR 5281 --- [           main] o.s.test.context.TestContextManager      : Caught exception while allowing TestExecutionListener [org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener@7fbdb894] to prepare test instance [com.dgs.soc.excelapi.integration.ExcelResourceIntegrationTest@2ad6895a]

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.dgs.soc.excelapi.integration.ExcelResourceIntegrationTest': Unsatisfied dependency expressed through field 'orderService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.dgs.soc.service.OrderServiceImpl' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:393) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:119) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener.prepareTestInstance(SpringBootDependencyInjectionTestExecutionListener.java:43) ~[spring-boot-test-autoconfigure-2.2.5.RELEASE.jar:2.2.5.RELEASE]
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:244) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) ~[junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) ~[junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) ~[junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) ~[junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) ~[junit-4.12.jar:4.12]
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) ~[junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363) ~[junit-4.12.jar:4.12]
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) ~[spring-test-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137) ~[junit-4.12.jar:4.12]
    at org.junit.runner.JUnitCore.run(JUnitCore.java:115) ~[junit-4.12.jar:4.12]
    at org.junit.vintage.engine.execution.RunnerExecutor.execute(RunnerExecutor.java:40) ~[junit-vintage-engine-5.5.2.jar:5.5.2]
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[na:na]
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) ~[na:na]
    at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133) ~[na:na]
    at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:na]
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
    at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[na:na]
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[na:na]
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
    at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:497) ~[na:na]
    at org.junit.vintage.engine.VintageTestEngine.executeAllChildren(VintageTestEngine.java:80) ~[junit-vintage-engine-5.5.2.jar:5.5.2]
    at org.junit.vintage.engine.VintageTestEngine.execute(VintageTestEngine.java:71) ~[junit-vintage-engine-5.5.2.jar:5.5.2]
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:229) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
    at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:197) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
    at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:211) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:191) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:137) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
    at org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run(JUnit5TestReference.java:89) ~[.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41) ~[.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:542) ~[.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:770) ~[.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:464) ~[.cp/:na]
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210) ~[.cp/:na]
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.dgs.soc.service.OrderServiceImpl' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1695) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1253) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1207) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.2.4.RELEASE.jar:5.2.4.RELEASE]
    ... 49 common frames omitted

2020-03-23 04:42:24.816  INFO 5281 --- [extShutdownHook] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'
2020-03-23 04:42:24.819  INFO 5281 --- [extShutdownHook] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2020-03-23 04:42:24.846  INFO 5281 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown initiated...
2020-03-23 04:42:24.875  INFO 5281 --- [extShutdownHook] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Shutdown completed.

@Description(value = "Resource layer for handling REST requests.")
@RestController
@RequestMapping("api")
public class ExcelResource {

    @Autowired
    OrderServiceImpl orderService;

    .......................................................
    .......................................................
    .......................................................
}

现在我尝试将该应用程序作为Spring Boot应用程序执行，我得到了同样的问题：

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

Description:

Field orderService in com.dgs.soc.excelapi.resources.ExcelResource required a bean of type 'com.dgs.soc.service.OrderServiceImpl' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.dgs.soc.service.OrderServiceImpl' in your configuration.

但是com.dgs.soc.service.OrderServiceImpl bean仍然存在，它由@service注释。

为什么我会得到这个问题？我错过了什么？如何尝试解决此问题？我在想我有一些参考问题或类似的东西，但我不知道

编辑-1：将@componentscan（“com.dgs.soc.service”）放在我的应用程序类的topo上，这似乎有效，但我有些怀疑！！！

这就是我的应用程序类：

package com.dgs.soc.excelapi;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan("com.dgs.soc.service")
public class Application extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        return builder.sources(Application.class);
    }
}

它可以工作，但是在没有**@componentscan（“com.dgs.soc.service”）**注释的情况下，它也应该可以工作，因为@SpringBootApplication注释了这个类，您可以在这里读到：

为什么？一些主意？

Answer 1

您的问题的答案是，您没有合适的包结构来进行spring-boot自动扫描，以拾取您的服务类别。

SpringBootApplication注释只允许扫描它所在的包及其子包。

如果在com.acme.app包中有SpringBootApplication类，那么所有带有Spring Boot注释的类都将在包com.acme.app及其任何子包中扫描，即com.acme.app.services、com.acme.app.controllors等。

你有两个选择；

>

您可以修改包结构以允许spring-boot自动扫描所有注释。在您的示例中，将应用程序类从com.dgs.soc.excelapi移动到com.dgs.soc。或者您可以将所有其他包（即service）移到com.dgs.soc.excelapi下。

您可以使用SpringBootApplication注释上的@componentscan或ScanBasePackages属性显式列出要扫描的包。