Spring装配机制
- 在xml中进行显示配置
- 在Java中进行显示配置
- 隐式bean发现机制和自动装配
自动化装配bean
- 组件扫描（component scanning），Spring会自动发现应用上下文中的bean
- 自动装配（autowiring），Spring自动满足bean之间的依赖
Speak.java
public interface Speak {
void say();
}
ChineseSpeak.java
@Component("chineseSpeak")
public class ChineseSpeak implements Speak {
public void say() {
System.out.println("用中文说");
}
}
SpeakConfig.java
@Component
@ComponentScan(basePackages = "com.xqh.spring.autowire")
public class SpeakConfig {
}
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpeakConfig.class)
public class SpeakTest {
@Autowired
private Speak speak;
@Test
public void sayTest(){
speak.say();
}
}
@Component注解告诉Spring这是一个组件类并为之创建bean，bean的id为首字母变小写的类名
@ComponentScan注解启用组件扫描并默认扫描与配置类相同的包
@Autowired注解会在Spring上下文中在自动装配符合的bean
通过java代码装配bean
创建配置类并标记 @Configuration注解
创建方法标记 @Bean注解
Speak.java
public interface Speak {
void say();
}
ChineseSpeak.java
public class ChineseSpeak implements Speak {
public void say(){
System.out.println("通过java代码装配-用中文说");
}
}
SpeakConfig.java
@Configuration
public class SpeakConfig {
@Bean
public Speak chineseSpeak() {
return new ChineseSpeak();
}
}
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpeakConfig.class)
public class SpeakTest {
@Autowired
private Speak speak;
@Test
public void sayTest(){
speak.say();
}
}
@Configuration标记的类表名是一个配置类并且包含在Spring上下文中如何创建bean的细节
@Bean注解告诉Spring这个方法将返回一个对象并且注册为Spring上下文中的bean
通过xml装配bean
- 创建Spring Xml配置文件
- 在JavaConfig中导入bean配置文件
Speak.java
public interface Speak {
void say();
}
ChineseSpeak.java
public class ChineseSpeak implements Speak {
public void say() {
System.out.println("通过xml装配bean-用中文说");
}
}
SpeakConfig.java
@Configuration
@ImportResource("classpath:spring-beans.xml")
public class SpeakConfig {
}
spring-beans.xml
<?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="chineseSpeak" class="com.xqh.spring.xmlconfig.ChineseSpeak"></bean>
</beans>
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpeakConfig.class)
public class SpeakTest {
@Autowired
private Speak speak;
@Test
public void sayTest(){
speak.say();
}
}