【Spring从入门到出家】3 - 使用注解开发和完全Java进行开发

现行主流的开发是以注解为主的

5 注解开发

• <context:annotation-config/>开启注解支持
• <context:component-scan base-package="com.cap.pojo" />组件扫描，将扫描指定路径下的所有类，类上含有@Component注解的类都会当成一个bean加载进容器
• @Component的特殊注解（下面这三者注解和@Component是等同的）
  • @Repository：持久层
  • @Service：业务层
  • @Controller：控制层

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

    <context:annotation-config/>
    <context:component-scan base-package="com.cap.pojo" />

</beans>

@Component
public class User {
    private String name;

    public String getName() {
        return name;
    }
}

6 完全Java开发

我们不使用xml配置文件的情况下进行开发

@Component
public class User {
    @Value("公孙离")
    private String name;

    public User(){
        System.out.println("User is instancing~~~");
    }

    public String getName() {
        return name;
    }
}

package com.cap.config;
@Configuration
public class Config {

    @Bean
    User getUser(){
        return new User();
    }
}

    @Test
    public void test(){
        ApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        User user = context.getBean(User.class);
        System.out.println(user);
        System.out.println(user.getName());
    }

结果得到

User is instancing~~~
com.cap.pojo.User@6cd24612
公孙离