Spring学习笔记(1)实现简单的Bean容器

github地址

代码目录结构

small-spring-step-01
└── src
    ├── main
    │   └── java
    │       └── cn.bugstack.springframework
    │           ├── BeanDefinition.java
    │           └── BeanFactory.java
    └── test
        └── java
            └── cn.bugstack.springframework.test  
                ├── bean
                │   └── UserService.java                
                └── ApiTest.java

定义BeanDefinition

用一个Object存放Bean对象

public class BeanDefinition {

    private Object bean;

    public BeanDefinition(Object bean) {
      this.bean = bean;
    }

    public Object getBean() {
      return bean;
    }

}

定义Bean工厂

包括Bean的注册和获取操作

public class BeanFactory {

    private Map<String, BeanDefinition> 
      beanDefinitionMap = new ConcurrentHashMap<>();

    public Object getBean(String name) {
      return beanDefinitionMap.get(name).getBean();
    }

    public void registerBeanDefinition(String name, BeanDefinition beanDefinition) 
    {
      beanDefinitionMap.put(name, beanDefinition);
    }
}

测试

定义了一个 UserService 对象

public class UserService {

    public void queryUserInfo(){
      System.out.println("查询用户信息");
    }

}

测试用例

@Test
public void test_BeanFactory(){
    // 1.初始化 BeanFactory
    BeanFactory beanFactory = new BeanFactory();
    
    // 2.注册 bean
    BeanDefinition beanDefinition = new BeanDefinition(new UserService());
    beanFactory.registerBeanDefinition("userService", beanDefinition);
    
    // 3.获取 bean
    UserService userService = (UserService) beanFactory.getBean("userService");
    userService.queryUserInfo();
}

成功初始化Bean工厂, 注册Bean, 获取Bean, 这样就实现了一个最简单的Bean容器