依赖注入

依赖注入

1.构造器注入

2.set注入

• 依赖注入
  • 依赖:bean对象的创建依赖于容器
  • 注入:bean对象中的所有属性,有容器来注入

环境搭建

1. 复杂类型

   public class Address {
       private String address;
       //    getter, setter, toString
   }
   

2. 真实对象

   public class Student {
       private String name;
       private Address address;
       private String[] books;
       private List<String> hobbies;
       private Map<String,String> card;
       private Set<String> games;
       private String girlfriend;
       private Properties info;
       //    getter, setter, toString
   }
   

3. 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"
          xsi:schemaLocation="http://www.springframework.org/schema/beans
           https://www.springframework.org/schema/beans/spring-beans.xsd">
       <bean id="address" class="cn.pinked.pojo.Address">
           <property name="address" value="earth"/>
       </bean>
       <bean id="student" class="cn.pinked.pojo.Student">
           <property name="name" value="大头儿子"/>
           <property name="address" ref="address"/>
           <property name="books">
               <array>
                   <value>西游记</value>
                   <value>三国演义</value>
                   <value>水浒传</value>
                   <value>红楼梦</value>
               </array>
           </property>
           <property name="hobbies">
               <list>
                   <value>唱</value>
                   <value>跳</value>
                   <value>rap</value>
                   <value>篮球</value>
               </list>
           </property>
           <property name="card">
               <map>
                   <entry key="studentcard" value="12345678"/>
                   <entry key="raedercard" value="12345678"/>
               </map>
           </property>
           <property name="games">
               <set>
                   <value>dead game</value>
               </set>
           </property>
           <property name="girlfriend">
               <null/>
           </property>
           <property name="info">
               <props>
                   <prop key="身高">150cm</prop>
                   <prop key="体重">50kg</prop>
               </props>
           </property>
       </bean>
   </beans>
   

4. 测试类

   @Test
   public void Student(){
       ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
       Student student = (Student) context.getBean("student");
       System.out.println(student.toString());
   }
   

3.扩展方式注入

可以使用p命名空间和c命名空间进行注入

<?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"
       xmlns:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="user" class="cn.pinked.pojo.User" p:name="大头儿子" p:age="6"/>

    <bean id="user2" class="cn.pinked.pojo.User" c:name="小头爸爸" c:age="37"/>

</beans>

• p命名空间和c命名空间不能直接使用,需要导入xml约束
• c命名空间需要有参构造器

4.bean的作用域

Scope	Description
singleton	(Default) Scopes a single bean definition to a single object instance for each Spring IoC container.
prototype	Scopes a single bean definition to any number of object instances.
request	Scopes a single bean definition to the lifecycle of a single HTTP request. That is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext.
session	Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext.
application	Scopes a single bean definition to the lifecycle of a ServletContext. Only valid in the context of a web-aware Spring ApplicationContext.
websocket	Scopes a single bean definition to the lifecycle of a WebSocket. Only valid in the context of a web-aware Spring ApplicationContext.

1. 单例模式(默认)

   <bean id="user" class="cn.pinked.pojo.User" p:name="大头儿子" p:age="6" scope="singleton"/>
   

2. 原型模式:每次从容器中get的时候,都会产生一个新对象

   <bean id="user" class="cn.pinked.pojo.User" p:name="大头儿子" p:age="6" scope="prototype"/>
   

3. 其余的作用于web的生命周期中