(4)spring的annotation

蔚落 2022-04-18 03:40 137阅读 0赞

**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"
        xmlns:context="http://www.springframework.org/schema/context"
        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">
    
        <context:annotation-config/>
    <context:component-scan base-package="spring"/>
    </beans>

**1.<context:annotation-config/>----打开spring的annotation**

**2.<context:component-scan base-package="spring"/>----设置从前缀为spring的包中找**

@Component("UserAction")
    //@Controller("UserAction")
    @Scope("prototype")
    public class UserAction {
    	private User user;
    	private int id;
    	private UserService UserService;
    	
    	
    	
    public UserAction() {
    	
    	}
    
    public UserAction(UserService userService) {
    		this.UserService = userService;
    	}
    
    
    public User getUser() {
    		return user;
    	}
    
    	public void setUser(User user) {
    		this.user = user;
    	}
    
    	public int getId() {
    		return id;
    	}
    
    	public void setId(int id) {
    		this.id = id;
    	}
    
    	public UserService getUserService() {
    		return UserService;
    	}
    @Resource
    	public void setUserService(UserService userService) {
    		this.UserService = userService;
    	}
    
    public void add() {
    	UserService.add(user);
    }
    
    public void delete() {
    	UserService.delete(id);
    }
    
    public void load() {
    	UserService.delete(id);
    }
    }

**@Component("userDao")相当于<bean id="userDao" class="spring.dao.UserDao">**

**@Scope("prototype")多例**

**@Resource() 自动完成依赖注入，默认通过byName(加在setXX前面)**

**@autoWired 默认通过类型（不建议使用，一个类有多个类型一样的属性就报错）**

**@Repository 一般用于dao的注入**

**@service 业务层，完成对service类的注入**

**@controller 控制层，完成对action类的注入**

**最佳实践；项目很大不建议使用annotation，项目很大，很多类，不会按照包分类，而是按照模块分，建议用xml**

**项目小的话用annotation还是很方便的。**