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

1 package org.lizf.demo;
2
3 public class UserDao {
4
5     public void login(String username, String password) {
6         System.out.println("login : " + username);
7     }
8
9 }

　　　　UserService.java

 1 package org.lizf.demo;
 2
 3 public class UserService {
 4
 5     private UserDao userDao;
 6
 7     public void login(String username, String password) {
 8         userDao.login(username, password);
 9     }
10
11     public void setUserDao(UserDao userDao) {
12         this.userDao = userDao;
13     }
14
15 }

　　　　spring-context.xml配置文件

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
 5
 6     <bean id="userDao" class="org.lizf.demo.UserDao" />
 7
 8     <bean id="userService" class="org.lizf.demo.UserService" >
 9         <property name="userDao" ref="userDao" />
10     </bean>
11
12 </beans>

　　　　Main.java测试类：

 1 package org.lizf.demo;
 2
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5
 6 public class Main {
 7
 8     public static void main(String[] args) {
 9         ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
10         UserService userService = (UserService) context.getBean("userService");
11         userService.login("admin", "****");
12     }
13
14 }

　　　　执行结果：

七月 19, 2016 1:28:17 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org[email protected]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:

 1 package org.lizf.demo;
 2
 3 import org.springframework.stereotype.Repository;
 4
 5 @Repository
 6 public class UserDao {
 7
 8     public void login(String username, String password) {
 9         System.out.println("login : " + username);
10     }
11
12 }

　　　　UserService.java:

 1 package org.lizf.demo;
 2
 3 import org.springframework.beans.factory.annotation.Autowired;
 4 import org.springframework.stereotype.Repository;
 5
 6 @Repository
 7 public class UserService {
 8
 9     @Autowired
10     private UserDao userDao;
11
12     public void login(String username, String password) {
13         userDao.login(username, password);
14     }
15
16 }

　　　　spring-context.xml配置扫描包：

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4     xmlns:context="http://www.springframework.org/schema/context"
 5     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
 6         http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">
 7
 8     <context:component-scan base-package="org.lizf.demo" />
 9
10
11 </beans>

　　　　Main.java测试类：

 1 package org.lizf.demo;
 2
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5
 6 public class Main {
 7
 8     public static void main(String[] args) {
 9         ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
10         UserService userService = (UserService) context.getBean("userService");
11         userService.login("admin", "****");
12     }
13
14 }

　　　　输出结果：

七月 19, 2016 1:40:40 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org[email protected]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：

1 package org.lizf.demo;
2
3 public class UserDao {
4
5     public void login(String username, String password) {
6         System.out.println("login : " + username);
7     }
8
9 }

　　　　UserService.java：

 1 package org.lizf.demo;
 2
 3 public class UserService {
 4
 5     private UserDao userDao;
 6
 7     public void login(String username, String password) {
 8         userDao.login(username, password);
 9     }
10
11     public void setUserDao(UserDao userDao) {
12         this.userDao = userDao;
13     }
14
15 }

　　　　SpringConfig.java 配置类：

 1 package org.lizf.demo;
 2
 3 import org.springframework.context.annotation.Bean;
 4 import org.springframework.context.annotation.Configuration;
 5
 6 //标注这是一个配置类
 7 @Configuration
 8 public class SpringConfig {
 9
10     //标注这是一个Bean
11     @Bean
12     public UserDao userDao() {
13         return new UserDao();
14     }
15
16     @Bean
17     public UserService userService() {
18         UserService userService = new UserService();
19         UserDao userDao = userDao();
20         userService.setUserDao(userDao);
21         return userService;
22     }
23
24 }

　　　　Main.java测试类：

 1 package org.lizf.demo;
 2
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 5
 6 public class Main {
 7     public static void main(String[] args) {
 8         //这里使用AnnotationConfigApplicationContext来创建ApplicationContext
 9         ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
10         UserService userService = (UserService) context.getBean("userService");
11         userService.login("admin", "****");
12     }
13 }

　　　　输出结果：

七月 19, 2016 1:53:55 上午 org.springframework.context.annotation.AnnotationConfigApplicationContext prepareRefresh
信息: Refreshing org.spring[email protected]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：

 1 package org.lizf.demo;
 2
 3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 4
 5 public class Main {
 6     public static void main(String[] args) {
 7         //如果有多个Config类，可以用下边的方式初始化
 8         AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
 9         //regiester方法接受可变参数，传入多个Config类
10         ctx.register(SpringConfig.class, SpringConfig2.class, SpringConfig3.class);
11         //刷新ApplicationContext使配置生效
12         ctx.refresh();
13     }
14 }