spring4.0@Configuration的使用

[TOC]
从Spring3.0,@Configuration用于定义配置类,可替换xml配置文件,被注解的类内部包含有一个或多个被@Bean注解的方法,这些方法将会被AnnotationConfigApplicationContext或AnnotationConfigWebApplicationContext类进行扫描,并用于构建bean定义,初始化Spring容器。

注意:@Configuration注解的配置类有如下要求:

@Configuration不可以是final类型;
@Configuration不可以是匿名类;
嵌套的configuration必须是静态类。

一、@Configuation加载Spring方法
1.1、@Configuration配置spring并启动spring容器

@Configuration标注在类上,相当于把该类作为spring的xml配置文件中的,作用为:配置spring容器(应用上下文)

package com.dxz.demo.configuration;

import org.springframework.context.annotation.Configuration;

@Configuration
public class TestConfiguration {
    public TestConfiguration() {
        System.out.println("TestConfiguration容器启动初始化。。。");
    }
}

相当于:






主方法进行测试:

package com.dxz.demo.configuration;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class TestMain {
    public static void main(String[] args) {

        // @Configuration注解的spring容器加载方式,用AnnotationConfigApplicationContext替换ClassPathXmlApplicationContext
        ApplicationContext context = new AnnotationConfigApplicationContext(TestConfiguration.class);

        // 如果加载spring-context.xml文件:
        // ApplicationContext context = new
        // ClassPathXmlApplicationContext("spring-context.xml");
    }
}

从运行主方法结果可以看出,spring容器已经启动了:

17:09:23.966 [main] DEBUG o.s.c.a.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@7f77e91b
17:09:24.062 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
17:09:24.794 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
17:09:24.806 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
17:09:24.814 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
17:09:24.824 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
17:09:24.866 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testConfiguration'
TestConfiguration容器启动初始化。。。

1.2、@Configuration启动容器+@Bean注册Bean,@Bean下管理bean的生命周期

@Bean标注在方法上(返回某个实例的方法),等价于spring的xml配置文件中的,作用为:注册bean对象

bean类:

package com.dxz.demo.configuration;

public class TestBean {

    private String username;
    private String url;
    private String password;

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

    public String toString() {
        return "username:" + this.username + ",url:" + this.url + ",password:" + this.password;
    }

    public void start() {
        System.out.println("TestBean 初始化。。。");
    }

    public void cleanUp() {
        System.out.println("TestBean 销毁。。。");
    }
}

配置类:

package com.dxz.demo.configuration;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;

@Configuration
public class TestConfiguration {
    public TestConfiguration() {
        System.out.println("TestConfiguration容器启动初始化。。。");
    }

    // @Bean注解注册bean,同时可以指定初始化和销毁方法
    // @Bean(name="testBean",initMethod="start",destroyMethod="cleanUp")
    @Bean
    @Scope("prototype")
    public TestBean testBean() {
        return new TestBean();
    }
}
18:12:51.320 [main] DEBUG o.s.c.a.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@7f77e91b
18:12:51.342 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
18:12:51.549 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
18:12:51.552 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
18:12:51.554 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
18:12:51.555 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalCommonAnnotationProcessor'
18:12:51.563 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testConfiguration'
TestConfiguration容器启动初始化。。。
TestBean sayHello...

注:
(1)、@Bean注解在返回实例的方法上,如果未通过@Bean指定bean的名称,则默认与标注的方法名相同;
(2)、@Bean注解默认作用域为单例singleton作用域,可通过@Scope(“prototype”)设置为原型作用域;
(3)、既然@Bean的作用是注册bean对象,那么完全可以使用@Component、@Controller、@Service、@Ripository等注解注册bean,当然需要配置@ComponentScan注解进行自动扫描。

@Bean下管理bean的生命周期

可以使用基于 Java 的配置来管理 bean 的生命周期。@Bean 支持两种属性,即 initMethod 和destroyMethod,这些属性可用于定义生命周期方法。在实例化 bean 或即将销毁它时,容器便可调用生命周期方法。生命周期方法也称为回调方法,因为它将由容器调用。使用 @Bean 注释注册的 bean 也支持 JSR-250 规定的标准 @PostConstruct 和 @PreDestroy 注释。如果您正在使用 XML 方法来定义 bean,那么就应该使用 bean 元素来定义生命周期回调方法。以下代码显示了在 XML 配置中通常使用 bean 元素定义回调的方法。

@Configuration
@ComponentScan(basePackages = "com.dxz.demo.configuration")
public class TestConfiguration {
    public TestConfiguration() {
        System.out.println("TestConfiguration容器启动初始化。。。");
    }

    //@Bean注解注册bean,同时可以指定初始化和销毁方法
    @Bean(name="testBean",initMethod="start",destroyMethod="cleanUp")
    @Scope("prototype")
    public TestBean testBean() {
        return new TestBean();
    }
}
public class TestMain {
    public static void main(String[] args) {

        ApplicationContext context = new AnnotationConfigApplicationContext(TestConfiguration.class);

        TestBean tb = (TestBean) context.getBean("testBean");
        tb.sayHello();
        System.out.println(tb);
        
        TestBean tb2 = (TestBean) context.getBean("testBean");
        tb2.sayHello();
        System.out.println(tb2);
    }
}

1.3、@Configuration启动容器+@Component注册Bean

bean类:

package com.dxz.demo.configuration;

import org.springframework.stereotype.Component;

//添加注册bean的注解
@Component
public class TestBean {

    private String username;
    private String url;
    private String password;

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

    public String toString() {
        return "username:" + this.username + ",url:" + this.url + ",password:" + this.password;
    }

    public void start() {
        System.out.println("TestBean 初始化。。。");
    }

    public void cleanUp() {
        System.out.println("TestBean 销毁。。。");
    }
}

配置类:

package com.dxz.demo.configuration;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;

@Configuration
//添加自动扫描注解,basePackages为TestBean包路径
@ComponentScan(basePackages = "com.dxz.demo.configuration")
public class TestConfiguration {
    public TestConfiguration() {
        System.out.println("TestConfiguration容器启动初始化。。。");
    }

    /*// @Bean注解注册bean,同时可以指定初始化和销毁方法
    // @Bean(name="testNean",initMethod="start",destroyMethod="cleanUp")
    @Bean
    @Scope("prototype")
    public TestBean testBean() {
        return new TestBean();
    }*/
}

主方法测试获取bean对象:

package com.dxz.demo.configuration;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class TestMain {
    public static void main(String[] args) {

        // @Configuration注解的spring容器加载方式,用AnnotationConfigApplicationContext替换ClassPathXmlApplicationContext
        ApplicationContext context = new AnnotationConfigApplicationContext(TestConfiguration.class);

        // 如果加载spring-context.xml文件:
        // ApplicationContext context = new
        // ClassPathXmlApplicationContext("spring-context.xml");
        
         //获取bean
        TestBean tb = (TestBean) context.getBean("testBean");
        tb.sayHello();
    }
}

sayHello()方法都被正常调用。

18:33:25.998 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testConfiguration'
TestConfiguration容器启动初始化。。。
18:33:26.004 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testBean'
TestBean sayHello...

@Configuation总结

@Configuation等价于

@Bean等价于

@ComponentScan等价于

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