Spring @EnableAutoConfiguration注解简介及使用示例

@EnableAutoConfiguration注解简介

 EnableAutoConfiguration是SpringBoot的一个特性
   可根据classpath中的jar依赖 
    自动注册bean,
 一般用于类或接口上
 它尝试根据您添加的jar依赖项自动配置Spring应用程序的IOC容器中
那么@EnableAutoConfiguration注解就是帮助SpringBoot程序完成这一自动装配功能
当然 @EnableAutoConfiguration注解 程序的原理,在框架SpringBoot的源码中

@EnableAutoConfiguration注解示例

  

1.编写自动装配类
package java265.beanConfig;
import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
 
@Data //省略get set toString的编写
@ConfigurationProperties(prefix = "spring.user")
public class User { 
    private String name;
}


2.配置信息 spring.factories(注意spring.factories的位置)
# 自动装配
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
java265.beanConfig.User

3.bean属性配置 application.yml

spring:
    user:
      name: java265

4.测试获取自动装配bean

package java265;
 
import java265.beanConfig.User;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
 
@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationTest {
 
	@Autowired
	private  User user;
 
	@Test
	public void testAutoCfg() {
		System.out.println(user);
	}
 
}

5.打印输出
User(name=java265)

6.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>java265</groupId>
    <artifactId>spring-boot-auto</artifactId>
    <version>1.0.0.RELEASE</version>
    <packaging>jar</packaging>
 
    <name>auto-boot</name>
    <description>EnableAutoConfiguration-demo</description>
 
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
        <relativePath/>
    </parent>
 
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
 
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
 
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>