spring依赖注入xml与注解对比

朱雀 2022-01-25 22:17 266阅读 0赞

# xml方式： #

<?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="student" class="com.ren.service.impl.Student">
            <property name="run" ref="runLong"></property>
            <property name="name" value="renhq"></property>
        </bean>
        <bean id="runLong" class="com.ren.service.impl.RunLong"></bean>
        <bean id="date" class="java.util.Date"></bean>
        <bean id="user" class="com.ren.model.User">
            <property name="name" value="renhq"></property>
            <property name="address" ref="address"></property>
        </bean>
        <bean id="address" class="com.ren.model.Address"></bean>
    </beans>

1、装配bean的方式：

UserFactory.createUser()为工厂返回一个User对象

<bean id="user01" class="com.ren.model.User"></bean>
    
        
        <bean id="user02" class="com.ren.service.impl.UserFactory" factory-method="createUser"></bean>
    
        
        
        <bean id="userfactory" class="com.ren.service.impl.UserFactory2"></bean>
        <bean id="user03" factory-bean="userfactory" factory-method="createUser"></bean>

2、bean的作用域（单例、多例）：

<bean id="user1" class="com.ren.model.User" scope="singleton"></bean>
    
        
        <bean id="user2" class="com.ren.model.User" scope="prototype"></bean>

3、bean的属性值注入：

<?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:p="http://www.springframework.org/schema/p"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        
        
            
            
            
        
        
        
            
            
            
        
    
        
        
            
            
            
        
    
        
        
        <bean id="student" class="com.ren.model.Student" p:age="21" p:password="123" p:username="ren"></bean>
    
    </beans>

4、SpEL表达式:

<bean id="customer" class="com.ren.model.Customer">
            <property name="name" value="#{'renhq'}"></property>
            <property name="sex" value="#{'man'}"></property>
            <property name="pi" value="#{T(java.lang.Math).PI}"></property>
            <property name="address" value="#{address}"></property>
            
        </bean>
        <bean id="address" class="com.ren.model.Address">
            <property name="name" value="#{'山东'}"></property>
        </bean>

5、集合属性注入:

<bean id="programma" class="com.ren.model.Programma">
            <property name="name" value="renhq"></property>
            
            <property name="cars">
                <list>
                    <value>宝马</value>
                    <value>奔驰</value>
                    <value>劳斯莱斯</value>
                </list>
            </property>
            
            <property name="pats">
                <set>
                    <value>小猫</value>
                    <value>小狗</value>
                </set>
            </property>
            
            <property name="infos">
                <map>
                    <entry key="1" value="11"></entry>
                    <entry key="2" value="22"></entry>
                </map>
            </property>
            
            <property name="mysqlInfo">
                <props>
                    <prop key="driver">com.mysql.jdbc.Driver</prop>
                    <prop key="url">jdbc:mysql://localhost:3306/databsename?useSSL=false</prop>
                    <prop key="user">root</prop>
                    <prop key="password">123456</prop>
                </props>
            </property>
            
            <property name="members">
                <array>
                    <value>哥哥</value>
                    <value>弟弟</value>
                </array>
            </property>
        </bean>

# 注解： #

xml文件开启注解（注意<beans/>标签中添加的内容）

1、默认情况下注解不生效，开启注解：

xml中配置：

添加：xmlns:context="http://www.springframework.org/schema/context"

xsi:schemaLocation=添加 http://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsd

2、注解使用：

bean注解：

> @Component("id")  配置bean
> 
>   
> web使用注解 action -> service -> dao \*
> 
> @Controller : action
> 
> @Service : service
> 
> @Repository : dao
> 
> 以上三种注解由Component衍生出，这三个注解代表不同的层级，加载顺序为Controller -> Service -> Repository
> 
>  
> 
> @Scope("prototype")  表示此bean开启多例模式

属性注解:

> @Autowired 根据类型注入属性 \* 如果是接口寻找实现类
> 
> @Qualifier("id")  根据id注入
> 
> @Resource("id")  根据id注入(查看源码，区别应该是Resource由jdk提供)
> 
>