Spring IOC

<dependencies>
    <!-- Spring核心容器 -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.0.2.RELEASE</version>
    </dependency>
    
    <!-- 日志相关 -->
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.2</version>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.12</version>
    </dependency>
    
    <!-- 测试框架 -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
        <scope>test</scope>
    </dependency>
</dependencies>

Spring配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       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
                           http://www.springframework.org/schema/context
                           http://www.springframework.org/schema/context/spring-context.xsd">
    
    <!-- 组件扫描配置 -->
    <context:component-scan base-package="com.qcby"/>
</beans>

传统方式和IOC方式对比

public class UserTest {
    
    // 传统创建对象方式
    @Test
    public void traditionalWay() {
        Demo demo = new Demo();
        demo.hello();
    }
    
    // IOC方式
    @Test
    public void iocWay() {
        // 1. 加载Spring配置文件
        ApplicationContext context = new ClassPathXmlApplicationContext("Spring.xml");
        // 2. 从容器中获取Bean
        Demo demo = (Demo) context.getBean("demo");
        demo.hello();
    }
}

服务器定义：

@Service
public class Demo {
    public void hello() {
        System.out.println("Hello Spring IOC!");
    }
}

Bean管理方式总结

xml方式

<!-- 简单Bean定义 -->
<bean id="demo" class="com.qcby.Demo"/>

<!-- Setter注入 -->
<bean id="cat" class="com.qcby.Cat">
    <property name="age" value="10"/>
    <property name="name" value="Tom"/>
    <property name="demo" ref="demo"/>
</bean>

<!-- 构造器注入 -->
<bean id="user" class="com.qcby.User">
    <constructor-arg name="height" value="10.00"/>
    <constructor-arg name="name" value="张三"/>
    <constructor-arg name="demo" ref="demo"/>
</bean>

<!-- 复杂类型注入 -->
<bean id="dog" class="com.qcby.Dog">
    <property name="arr">
        <array>
            <value>1</value>
            <value>2</value>
        </array>
    </property>
    <property name="list">
        <list>
            <value>Item1</value>
            <value>Item2</value>
        </list>
    </property>
    <property name="map">
        <map>
            <entry key="key1" value="value1"/>
            <entry key="key2" value="value2"/>
        </map>
    </property>
</bean>

注解方式

@Service
public class UserServiceImpl implements UserService {
    
    @Value("${jdbc.url}")
    private String jdbcUrl;
    
    @Autowired
    private UserRepository userRepository;
    
    // ...
}

纯注解方式

@Configuration
@ComponentScan("com.qcby")
@PropertySource("classpath:app.properties")
public class AppConfig {
    
    @Bean
    public DataSource dataSource() {
        // 配置数据源
        return new DruidDataSource();
    }
}