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

IoC核心設計模式

Factory 模式和 Observer 模式，強制使用 依賴注入 模式。

DI原則

1/2 高層模塊不應該依賴低層模塊，而是依賴抽象，低層模塊也應該依賴抽象。 比如 controller 依賴 IXXXService ，而不是依賴 XXXServiceImpl。

DI注入方式

• 1 Setter注入
• 2 構造注入
• 3 接口注入 spring沒有實現 avalon有實現
• go cloud —— wired 可能是第4種

POJO 注冊成 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;}} 復制代碼<?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>復制代碼

構造注入

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;}} 復制代碼<?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> 復制代碼

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;}}復制代碼<?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> 復制代碼

Bean跟Bean之間依賴

<?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>復制代碼

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從外部配置啟動應用程序

Spring可以加載來自

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

ApplicationContext是應用程序級別，BeanFactory是系統級別。 使用 AppCtx 不同實現，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() + "'");}} 復制代碼<?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> 復制代碼

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單元測試

@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);}}復制代碼<?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> 復制代碼

獲取源代碼文件

github.com/spring-by-e…

1/ 注意如果使用IDEA , 使用改命令轉換

mvn idea:idea 復制代碼

轉載于:https://juejin.im/post/5cdfad886fb9a07ea567beeb

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