springboot报错

Question

配置文件 版本信息

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.yzpc</groupId>
    <artifactId>chapter02</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>chapter02</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

包结构

parson类

package com.yzpc.entity;

import com.yzpc.entity.Pet;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
//import java.util.*;
@Component
@ConfigurationProperties(prefix = "person")
public class Person {

    private int id;
    private String name;
    private List hobby;
    private String[] family;
    private Map map;
    private Pet pet;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List getHobby() {
        return hobby;
    }

    public void setHobby(List hobby) {
        this.hobby = hobby;
    }

    public String[] getFamily() {
        return family;
    }

    public void setFamily(String[] family) {
        this.family = family;
    }

    public Map getMap() {
        return map;
    }

    public void setMap(Map map) {
        this.map = map;
    }

    public Pet getPet() {
        return pet;
    }

    public void setPet(Pet pet) {
        this.pet = pet;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", hobby=" + hobby +
                ", family=" + Arrays.toString(family) +
                ", map=" + map +
                ", pet=" + pet +
                '}';
    }
}

Pet类

package com.yzpc.entity;

public class Pet {
    private String type;
    private String name;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Pet{" +
                "type='" + type + '\'' +
                ", name='" + name + '\'' +
                '}';
    }
}

测试类

package com.example.demo;

import com.yzpc.entity.Person;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class Chapter02ApplicationTests {
    @Autowired(required=false)
    private Person person;

    @Test
    void contextLoads() {
        System.out.println(person);
    }

}

在测试类加(required=false)的报错
OpenJDK 64-Bit Server VM warning: Sharing is only supported for boot loader classes because bootstrap classpath has been appended
null
而我想要的输出

在测试类不加(required=false)的报错

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.example.demo.Chapter02ApplicationTests': Unsatisfied dependency expressed through field 'person': No qualifying bean of type 'com.yzpc.entity.Person' 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$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:788)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:768)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:145)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:509)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1439)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:398)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:143)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:98)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:260)
    at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:163)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.StreamSpliterators$WrappingSpliterator.forEachRemaining(StreamSpliterators.java:310)
    at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:735)
    at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:734)
    at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762)
    at java.base/java.util.Optional.orElseGet(Optional.java:364)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.yzpc.entity.Person' 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:1880)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1406)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1353)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:785)
    ... 21 more

Answer 1

以下回复参考：皆我百晓生、券券喵儿等免费微信小程序作答:

根据你提供的错误信息，问题出现在你试图通过Spring的自动装配功能将Person类的对象注入到Chapter02ApplicationTests类中，但Spring无法找到匹配的bean来注入。这可能是由于以下几个原因造成的：

1. 没有定义Person类的bean：在你的Spring配置中可能没有定义Person类的bean。Spring需要从配置文件或注解中找到这个bean才能注入到测试类中。如果你使用Java配置，你可以在配置类中使用@Bean注解来定义bean。如果你使用XML配置，你可以在XML文件中定义bean。
2. 扫描路径问题：确保Spring能够扫描到Person类所在的包。如果你使用Java配置，检查你的@ComponentScan注解是否包括了Person类所在的包。如果你使用XML配置，检查你的context配置文件中是否包括了Person类所在的包或路径。
3. 配置问题：确保你的Spring配置正确加载了application.properties或application.yml文件，并且这些文件中定义了需要的属性。此外，检查是否有任何语法错误或缺失的配置项。

解决方案：

• 确保在Spring配置中定义了Person类的bean。你可以在你的Java配置类中添加如下代码：

@Configuration
public class AppConfig {
    @Bean
    public Person person() {
        return new Person();
    }
}

或者在你的XML配置文件中添加如下代码：

<bean id="person" class="com.yzpc.entity.Person"/>

• 确保Spring能够扫描到Person类所在的包。你可以检查并更新你的@ComponentScan注解或XML配置中的相关路径。
• 检查并修复任何配置问题，包括application.properties或application.yml文件中的属性定义和语法。

注意：在你的测试类中，使用@Autowired注解时，如果对应的bean在Spring容器中不存在，你可以通过设置required属性为false来避免抛出异常。但这并不意味着Spring会创建一个新的bean实例并注入到测试类中，它仍然会尝试从Spring容器中获取匹配的bean。如果没有匹配的bean可用，它将不会进行任何注入，但也不会抛出异常。然而，这可能导致你的测试失败，因为你试图使用一个未初始化的对象。因此，最好确保Spring容器中有一个可用的匹配bean。