【Spring第四篇】DI注入以及c、p命名空间

比眉伴天荒 2023-09-29 09:36 87阅读 0赞

### DI注入以及c、p命名空间 ###

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`编写实体类`

Address

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class Address {
        
        private String address;
    
    }

Student

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class Student {
        
    
        private String name;
        private Address address;
        private String[] books;
        private List<String> hobbys;
        private Map<String, String> card;
        private Set<String> games;
        private String wife;
        private Properties info;
    
    }

User

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class User {
        
    
        private String name;
        private int age;
    
    }

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`将实体类都注入到bean中，编程一个个bean`

#### `p命名空间、c命名空间` ####

`userbean.xml 用于将实体类User注入到spring容器中，交给spring托管`

<?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
       http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
    
    
    
        <bean id="user" class="com.kk.pojo.User" p:name="王五" p:age="22"/>
    
    
        
    
    
    
        <bean id="user2" class="com.kk.pojo.User" c:name="赵六" c:age="20" scope="prototype"/>
    
    </beans>

注意：需要导入以下xmlns

`xmlns:p="http://www.springframework.org/schema/p`

`xmlns:c="http://www.springframework.org/schema/c`

`p命名空间`

p 命名空间注入，可以直接注入属性的值 property

`c命名空间`

c 命名空间注入  需要构造器  construct-args 
    singleton 单例模式  Spring的默认机制
    prototype原型模式 每次从容器中get的时候，每一次都会产生一个新对象

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#### `测试各种类型的注入` ####

`仔细阅读注解`

`beans.xml 用于将实体类Address，Student注入到spring容器中，交给spring托管`

<?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-3.0.xsd">
    
    
        <bean id="address" class="com.kk.pojo.Address">
            <property name="address" value="广东"/>
        </bean>
    
        <bean id="student" class="com.kk.pojo.Student">
    
            <property name="name" value="小六"/>
    
    
            <property name="address" ref="address"/>
    
    
    
            <property name="books">
                <array>
                    <value>Java程序设计</value>
                    <value>SSM</value>
                    <value>微服务</value>
                </array>
            </property>
    
    
    
            <property name="hobbys">
                <list>
                    <value>敲代码</value>
                    <value>赚钱</value>
                    <value>唱歌</value>
                    <value>运动</value>
                </list>
            </property>
    
    
    
            <property name="card">
                <map>
                    <entry key="学号" value="2011101**"/>
                    <entry key="身份证" value="4418 **** **** ****..."/>
                </map>
            </property>
    
    
            <property name="games">
                <set>
                    <value>CSOL</value>
                    <value>王者</value>
                </set>
            </property>
    
    
    
            <property name="wife">
                <null/>
            </property>
    
    
            <property name="info">
                <props>
                    <prop key="邮箱">30666@qq.com</prop>
                    <prop key="qq">30666</prop>
                    <prop key="性别">男</prop>
                </props>
            </property>
            
        </bean>
    
    
    
    </beans>

`property中的name里边的参数对应的是实体类中的属性字段`

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测试：

public class Test {
        
    
        @org.junit.Test
        public void testAddress(){
        
            ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
            Address address = (Address) context.getBean("address");
            System.out.println(address);
        }
    
    
        public static void main(String[] args) {
        
           ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
            Student student = (Student) context.getBean("student");
            System.out.println(student.toString());
    
        }
    
    
        @org.junit.Test
        public void test2(){
        
          ApplicationContext context = new ClassPathXmlApplicationContext("userbean.xml");
            User user = context.getBean("user", User.class);
            User user2 = context.getBean("user2", User.class);
            System.out.println(user==user2);//结果为  false 这就是单例模式 singleton
    
        }
    
    }

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[img-si7vZOEQ-1649573024969_C_Users_30666_AppData_Roaming_Typora_typora-user-images_image-20220310143143176.png]: https://img-blog.csdnimg.cn/ee7f9b42eeac4b92b2d48d9a497b2999.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5LiD5a-75YyX6YeM,size_19,color_FFFFFF,t_70,g_se,x_16