• Spring57


    熟悉spring:
    项目结构如下:

    spring-study2的pom.xml文件中添加以下依赖:

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>5.3.17</version>
    </dependency>
    
    <!-- https://mvnrepository.com/artifact/junit/junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.13.1</version>
        <scope>test</scope>
    </dependency>
    

    Cat类如下:

    package com.kuang.pojo;
    
    public class Cat {
        public void shout(){
            System.out.println("miao~");
        }
    }
    
    

    Dog类如下:

    package com.kuang.pojo;
    
    public class Dog {
        public void shout(){
            System.out.println("wang~");
        }
    }
    

    People类如下:

    package com.kuang.pojo;
    
    public class People {
        private Cat cat;
        private Dog dog;
        private String name;
    
        public Cat getCat() {
            return cat;
        }
    
        public Dog getDog() {
            return dog;
        }
    
        public String getName() {
            return name;
        }
    
        public void setCat(Cat cat) {
            this.cat = cat;
        }
    
        public void setDog(Dog dog) {
            this.dog = dog;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        @Override
        public String toString() {
            return "People{" +
                    "cat=" + cat +
                    ", dog=" + dog +
                    ", name='" + name + '\'' +
                    '}';
        }
    }
    

    MyTest类如下:

    import com.kuang.pojo.People;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class MyTest {
        @Test
        public void test1(){
            ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
    
            People people = context.getBean("people",People.class);
            people.getCat().shout();
            people.getDog().shout();
        }
    }
    

    beans.xml添加如下:

    <bean id="dog" class="com.kuang.pojo.Dog"/>
    <bean id="cat" class="com.kuang.pojo.Cat"/>
    
    <bean id="people" class="com.kuang.pojo.People">
        <property name="name" value="陆迁加油呀~"/>
        <property name="cat" ref="cat"/>
        <property name="dog" ref="dog"/>
    </bean>
    

    之后可以运行MyTest!
    输出如下:

    使用注解自动装配:

    1.导入约束:context约束
    2.配置注解的支持:context:annotation-config【重要!】

    <?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">
    
        <!--开启注解的支持-->
        <context:annotation-config/>
    
        <bean id="cat" class="com.kuang.pojo.Cat"/>
        <bean id="dog" class="com.kuang.pojo.Dog"/>
        <bean id="people" class="com.kuang.pojo.People"/>
    
    </beans>
    

    在People类做添加@Autowired,也可以删掉此类中的set方法:

    @Autowired
    使用Autowired我们可以不用编写set方法,前提是你这个自动装配的属性在IOC(Spring)容器中存在,且符合byType!

    注解说明

    • @Autowired:自动装配通过类型。名字
      • 如果Autowired不能唯一自动装配上属性,则需要通过@Qualifier(value="xxx")
    • @Nullable:字段标记了这个注解,说明这个字段可以为null
    • @Resource:自动装配通过名字。类型
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  • 原文地址:https://www.cnblogs.com/techgy/p/16085947.html
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