@Configuration

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（一）标注在类上的应用

@Configuration作用等同于xml 中的<beans></beans> 标签
MyConfigurationTest.java文件

@Configuration
public class MyConfigurationTest {
    
}

spring-context.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">    
</beans>

MyConfigurationTest.java的作用等同于spring-context.xml文件

• 测试一下

• xml写法

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id ="myConfigTest" class ="vi.test.MyConfigurationTest2"></bean>
</beans>

public class MyConfigurationTest2 {

    public MyConfigurationTest2() {
        System.out.println("MyConfigurationTest2()     *******");
    }
}

• @Configuration写法·

@Configuration
public class MyConfigurationTest {

    public MyConfigurationTest() {
        System.out.println("MyConfigurationTest()   *******");
    }
}

• test类

public class TestConfig {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyConfigurationTest.class);
     
        ApplicationContext context2 = new ClassPathXmlApplicationContext("spring-context.xml");
    }
}

• 执行结果
  

• 文件结构
  

（二）@Configuration+@Bean

@Bean相当于xml中的<bean></bean> 标签

public class MyBeanTest {

    public void test() {
        System.out.println("MyBeanTest的test()");
    }

    public void init() {
        System.out.println("init()");
    }

    public void destroy() {
        System.out.println("destroy()");
    }
}

@Configuration
public class MyConfigurationTest {

    public MyConfigurationTest() {
        System.out.println("MyConfigurationTest()   *******");
    }

    @Bean(name="myBeanTest",initMethod = "init",destroyMethod = "destroy")
    @Scope("prototype") // 根据需要定义
    public  MyBeanTest myBeanTest(){
        return new MyBeanTest();
    }
}

• test

public class TestConfig {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyConfigurationTest.class);
        MyBeanTest myBeanTest = (MyBeanTest)context.getBean("myBeanTest");
        myBeanTest.test();
    }
}

• 运行结果
  

（三）@Configuration+@Import

• 普通类

public class MyBeanTest {

    public void test() {
        System.out.println("MyBeanTest的test()");
    }

    public void init() {
        System.out.println("init()");
    }

    public void destroy() {
        System.out.println("destroy()");
    }
}

• @Import注解

@Configuration
@Import(MyBeanTest.class)
public class MyConfigurationTest {

    public MyConfigurationTest() {
        System.out.println("MyConfigurationTest()   *******");
    }
}

• test类

public class TestConfig {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyConfigurationTest.class);
        MyBeanTest myBeanTest = (MyBeanTest)context.getBean(MyBeanTest.class);
        myBeanTest.test();
    }
}

• 运行结果
  

（四）@Configuration+@ComponentScan+@Component

springboot启动类的用法，只不过springboot的启动类的注解为联合注解
大致意思是@ComponentScan(basePackages={"包路径A","包路径B",···})扫描指定路径下的包路径A,包路径B···下的被@Component注解的类

• 加上@ComponentScan注解

@Configuration
@ComponentScan(basePackages = {"vi.test"})
public class MyConfigurationTest {

    public MyConfigurationTest() {
        System.out.println("MyConfigurationTest()   *******");
    }
}

• 加上@Component注解

@Component
public class MyBeanTest {

    public void test() {
        System.out.println("MyBeanTest的test()");
    }

    public void init() {
        System.out.println("init()");
    }

    public void destroy() {
        System.out.println("destroy()");
    }
}

• test类

public class TestConfig {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyConfigurationTest.class);
        MyBeanTest myBeanTest = (MyBeanTest)context.getBean("myBeanTest");
        myBeanTest.test();
    }
}

• 运行结果