@Configuration

每天都過的很快，今天de我依舊碌碌無為，心情依舊很down,加油 ,加油,小菜🦆

（一）標注在類上的應用

@Configuration作用等同於xml 中的<beans></beans> 標簽
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的作用等同於spring-context.xml文件

• 測試一下

• xml寫法

<?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寫法·

@Configuration
public class MyConfigurationTest {

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

• test類

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

• 執行結果
  

• 文件結構
  

（二）@Configuration+@Bean

@Bean相當於xml中的<bean></bean> 標簽

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") // 根據需要定義
    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();
    }
}

• 運行結果
  

（三）@Configuration+@Import

• 普通類

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類

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

• 運行結果
  

（四）@Configuration+@ComponentScan+@Component

springboot啟動類的用法，只不過springboot的啟動類的注解為聯合注解
大致意思是@ComponentScan(basePackages={"包路徑A","包路徑B",···})掃描指定路徑下的包路徑A,包路徑B···下的被@Component注解的類

• 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類

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

• 運行結果