Spring随笔 —— IOC配置的三种不同方式简介

　　在spring framework中，IOC的配置是最基础的部分，常见的配置方式有基于xml文件和基于注解的配置方式。除了这两种配置方式之外，今天这里再介绍另一种配置方式，先用小demo重温下我们熟悉的两种配置方式。

　　UserService调用UserDao中的login(String username, String password)方法。

　　一、基于XML配置文件的方式

　　　　UserDao.java

package org.lizf.demo;

public class UserDao {

    public void login(String username, String password) {
        System.out.println("login : " + username);
    }
    
}

　　　　UserService.java

package org.lizf.demo;

public class UserService {
    
    private UserDao userDao;
    
    public void login(String username, String password) {
        userDao.login(username, password);
    }

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
    
}

　　　　spring-context.xml配置文件

<?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">
    
    <bean id="userDao" class="org.lizf.demo.UserDao" />
    
    <bean id="userService" class="org.lizf.demo.UserService" >
        <property name="userDao" ref="userDao" />
    </bean>

</beans>

　　　　Main.java测试类：

package org.lizf.demo;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
        UserService userService = (UserService) context.getBean("userService");
        userService.login("admin", "****");
    }

}

　　　　执行结果：

七月 19, 2016 1:28:17 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5010be6: startup date [Tue Jul 19 01:28:17 CST 2016]; root of context hierarchy
七月 19, 2016 1:28:17 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [spring-context.xml]
login : admin

　　二、基于注解的配置方式

　　　　UserDao.java:

package org.lizf.demo;

import org.springframework.stereotype.Repository;

@Repository
public class UserDao {

    public void login(String username, String password) {
        System.out.println("login : " + username);
    }
    
}

　　　　UserService.java:

package org.lizf.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

@Service
public class UserService {
    
    @Autowired
    private UserDao userDao;
    
    public void login(String username, String password) {
        userDao.login(username, password);
    }

}

　　　　spring-context.xml配置扫描包：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
    
    <context:component-scan base-package="org.lizf.demo" />
    

</beans>

　　　　Main.java测试类：

package org.lizf.demo;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
        UserService userService = (UserService) context.getBean("userService");
        userService.login("admin", "****");
    }

}

　　　　输出结果：

七月 19, 2016 1:40:40 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5010be6: startup date [Tue Jul 19 01:40:40 CST 2016]; root of context hierarchy
七月 19, 2016 1:40:40 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [spring-context.xml]
login : admin

　　三、基于Java类的配置方式：

　　　　UserDao.java：

package org.lizf.demo;

public class UserDao {

    public void login(String username, String password) {
        System.out.println("login : " + username);
    }
    
}

　　　　UserService.java：

package org.lizf.demo;

public class UserService {
    
    private UserDao userDao;
    
    public void login(String username, String password) {
        userDao.login(username, password);
    }
    
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

}

　　　　SpringConfig.java 配置类：

package org.lizf.demo;

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

//标注这是一个配置类
@Configuration
public class SpringConfig {
    
    //标注这是一个Bean
    @Bean
    public UserDao userDao() {
        return new UserDao();
    }
    
    @Bean
    public UserService userService() {
        UserService userService = new UserService();
        UserDao userDao = userDao();
        userService.setUserDao(userDao);
        return userService;
    }
    
}

　　　　Main.java测试类：

package org.lizf.demo;

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

public class Main {
    public static void main(String[] args) {
        //这里使用AnnotationConfigApplicationContext来创建ApplicationContext
        ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        UserService userService = (UserService) context.getBean("userService");
        userService.login("admin", "****");
    }
}

　　　　输出结果：

七月 19, 2016 1:53:55 上午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@179d3b25: startup date [Tue Jul 19 01:53:55 CST 2016]; root of context hierarchy
login : admin

　　　　如果需要对多个Config类进行加载，可以使用如下方式：

package org.lizf.demo;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {
    public static void main(String[] args) {
        //如果有多个Config类，可以用下边的方式初始化
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        //regiester方法接受可变参数，传入多个Config类
        ctx.register(SpringConfig.class, SpringConfig2.class, SpringConfig3.class);
        //刷新ApplicationContext使配置生效
        ctx.refresh();
    }
}