Java进阶知识19 Spring对象依赖关系的几种写法

Z时代
2024-01-10
分类：综合

java

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xmlns:aop="http://www.springframework.org/schema/aop"
 5        xmlns:tx="http://www.springframework.org/schema/tx"
 6        xmlns:p="http://www.springframework.org/schema/p"    
 7        xsi:schemaLocation="
 8        http://www.springframework.org/schema/beans
 9        http://www.springframework.org/schema/beans/spring-beans.xsd
10        http://www.springframework.org/schema/tx
11        http://www.springframework.org/schema/tx/spring-tx.xsd
12        http://www.springframework.org/schema/aop
13        http://www.springframework.org/schema/aop/spring-aop.xsd">
14 
15     <!-- 1、set方法注入值（依赖），层层分离 -->
16     <!-- Dao层 --> <!-- 无参构造器用：property  有参构造器用：constructor-arg --> 
17     <bean id="userDao1" class="com.bw.dao.UserDao">
18         <property name="name" value="Huang Long"></property>
19     </bean>
20     <!-- service层 -->
21     <bean id="userService1" class="com.bw.service.UserService">
22         <property name="userDao" ref="userDao1"></property>
23     </bean>
24     <!-- Action层、多例-->
25     <bean id="userAction1" class="com.bw.action.UserAction" scope="prototype">
26         <property name="userService" ref="userService1"></property>
27     </bean>
28     <!-- ========================================================================== -->
29     
30     <!-- 2、set方法注入值（依赖），层层嵌套 -->
31     <bean id="userAction2" class="com.bw.action.UserAction">
32         <property name="userService">
33             <bean class="com.bw.service.UserService">
34                 <property name="userDao">
35                     <bean class="com.bw.dao.UserDao">
36                         <property name="name"><value>Huang Long</value></property>
37                     </bean>
38                 </property>
39             </bean>
40         </property>
41     </bean>
42     <!-- ========================================================================== -->
43     
44     <!-- 3、p名称空间 ,头部要引入xmlns:p="http://www.springframework.org/schema/p"-->
45     <!-- Dao层 -->
46     <bean id="userDao3" class="com.bw.dao.UserDao">
47         <property name="name" value="Huang Long"></property>
48     </bean>
49     <!-- service层 -->
50     <bean id="userService3" class="com.bw.service.UserService" p:userDao-ref="userDao3"></bean>
51     <!-- Action层、多例-->
52     <bean id="userAction3" class="com.bw.action.UserAction" p:userService-ref="userService3" scope="prototype"></bean>
53 </beans>

下面两种方式，不建议使用：

1、自动装配

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xmlns:aop="http://www.springframework.org/schema/aop"
 5        xmlns:tx="http://www.springframework.org/schema/tx"  
 6        xsi:schemaLocation="
 7        http://www.springframework.org/schema/beans
 8        http://www.springframework.org/schema/beans/spring-beans.xsd
 9        http://www.springframework.org/schema/tx
10        http://www.springframework.org/schema/tx/spring-tx.xsd
11        http://www.springframework.org/schema/aop
12        http://www.springframework.org/schema/aop/spring-aop.xsd">
13        <!--  default-autowire="byName" 可以配置全局自动装配 -->
14       
15     <!-- 4、自动装配（局部） --> <!-- 自动装配方式，不建议使用，1、增加服务器负担；2、大项目不好维护 -->
16     <!-- Dao层 -->
17     <bean id="userDao" class="com.bw.dao.UserDao">
18         <property name="name" value="Huang Long"></property>
19     </bean>
20     
21     <!-- service层 -->
22     <bean id="userService" class="com.bw.service.UserService" autowire="byName"></bean>
23     
24     <!-- Action层、多例-->
25     <bean id="userAction4" class="com.bw.action.UserAction" autowire="byName" scope="prototype"></bean>
26 </beans>

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xmlns:aop="http://www.springframework.org/schema/aop"
 5        xmlns:tx="http://www.springframework.org/schema/tx"  
 6        xsi:schemaLocation="
 7        http://www.springframework.org/schema/beans
 8        http://www.springframework.org/schema/beans/spring-beans.xsd
 9        http://www.springframework.org/schema/tx
10        http://www.springframework.org/schema/tx/spring-tx.xsd
11        http://www.springframework.org/schema/aop
12        http://www.springframework.org/schema/aop/spring-aop.xsd" default-autowire="byName">
13        <!--  default-autowire="byName" 可以配置全局自动装配 -->
14       
15     <!-- 4、自动装配（全局） --> <!-- 自动装配方式，不建议使用，1、增加服务器负担；2、大项目不好维护 -->
16     <!-- Dao层 -->
17     <bean id="userDao" class="com.bw.dao.UserDao">
18         <property name="name" value="Huang Long"></property>
19     </bean>
20     
21     <!-- service层 -->
22     <bean id="userService" class="com.bw.service.UserService" ></bean>
23     
24     <!-- Action层、多例-->
25     <bean id="userAction4" class="com.bw.action.UserAction" scope="prototype"></bean>
26 </beans>