IoC = DI（Dependency Injection ） + 生命周期钩子事件 + 外部配置 ...

IoC核心设计模式

Factory 模式和 Observer 模式，强制使用 依赖注入 模式。

DI原则

1/2 高层模块不应该依赖低层模块，而是依赖抽象，低层模块也应该依赖抽象。 比如 controller 依赖 IXXXService ，而不是依赖 XXXServiceImpl。

DI注入方式

• 1 Setter注入
• 2 构造注入
• 3 接口注入 spring没有实现 avalon有实现
• go cloud —— wired 可能是第4种

POJO 注册成 Bean

public class DefaultMessage {private String message = "Spring is fun.";/*** Gets message.*/public String getMessage() {return message;}/*** Sets message.*/public void setMessage(String message) {this.message = message;}}
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<?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="message"class="org.springbyexample.di.xml.DefaultMessage" /></beans>复制代码

构造注入

public class ConstructorMessage {private String message = null;/*** Constructor*/public ConstructorMessage(String message) {this.message = message;}/*** Gets message.*/public String getMessage() {return message;}/*** Sets message.*/public void setMessage(String message) {this.message = message;}}
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<?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="message"class="org.springbyexample.di.xml.ConstructorMessage"><constructor-arg value="Spring is fun." /></bean></beans>
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Setter注入

public class SetterMessage {private String message = null;/*** Gets message.*/public String getMessage() {return message;}/*** Sets message.*/public void setMessage(String message) {this.message = message;}}复制代码

<?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="message"class="org.springbyexample.di.xml.SetterMessage"><property name="message" value="Spring is fun." /></bean></beans>
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Bean跟Bean之间依赖

<?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="springMessage" class="java.lang.String"><constructor-arg value="Spring is fun." /></bean><bean id="message"class="org.springbyexample.di.xml.SetterMessage"><property name="message" ref="springMessage" /></bean></beans>复制代码

从外部配置启动应用程序

Spring可以加载来自

• classpath
• file sys
• ftp
• http
• ...任何外部的配置文件

ApplicationContext是应用程序级别，BeanFactory是系统级别。 使用 AppCtx 不同实现，比如 ClassPathXmlApplicationContext

public class MessageRunner {final static Logger logger = LoggerFactory.getLogger(MessageRunner.class);/*** Main method.*/public static void main(String[] args) {logger.info("Initializing Spring context.");ApplicationContext applicationContext = new ClassPathXmlApplicationContext("/application-context.xml");logger.info("Spring context initialized.");Message message = (Message) applicationContext.getBean("message");logger.debug("message='" + message.getMessage() + "'");}}
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<?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="message"class="org.springbyexample.di.app.Message"><property name="message" value="Spring is fun." /></bean></beans>
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单元测试

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class SetterMessageTest {final Logger logger = LoggerFactory.getLogger(SetterMessageTest.class);@Autowiredprivate SetterMessage message = null;/*** Tests message.*/@Testpublic void testMessage() {   assertNotNull("Constructor message instance is null.", message);String msg = message.getMessage();assertNotNull("Message is null.", msg);String expectedMessage = "Spring is fun.";assertEquals("Message should be '" + expectedMessage + "'.", expectedMessage, msg);logger.info("message='{}'", msg);}}复制代码

<?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="message"class="org.springbyexample.di.xml.SetterMessage"><property name="message" value="Spring is fun." /></bean></beans>
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获取源代码文件

github.com/spring-by-e…

1/ 注意如果使用IDEA , 使用改命令转换

mvn idea:idea
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