【Spring基础】IOC使用构造器依赖注入

一时失言乱红尘 2022-06-03 00:56 191阅读 0赞

# 前言 #

Github：[https://github.com/yihonglei/thinking-in-spring][https_github.com_yihonglei_thinking-in-spring]（spring-ioc-xml工程）

# 一 构造器注入bean #

**1、创建HelloService接口**

package com.jpeony.spring.common;
    
    /**
     * @author yihonglei
     */
    public interface HelloService {
        void sayHello(String name);
    }

**2、HelloServiceImpl实现类**

package com.jpeony.spring.common;
    
    /**
     * @author yihonglei
     */
    public class HelloServiceImpl implements HelloService {
    
        @Override
        public void sayHello(String name) {
            System.out.println("hello:" + name);
        }
    }

**3、SelfIntroductionService(自我介绍)接口**

package com.jpeony.spring.constructor;
    
    /**
     * @author yihonglei
     */
    public interface SelfIntroductionService {
        void selfIntroduction();
    }

**4、SelfIntroductionServiceImpl实现类**

package com.jpeony.spring.constructor;
    
    import com.jpeony.spring.common.HelloService;
    
    /**
     * @author yihonglei
     */
    public class SelfIntroductionServiceImpl implements SelfIntroductionService {
        private HelloService helloService;
    
        /**
         * 构造器注入Bean
         */
        public SelfIntroductionServiceImpl(HelloService helloService) {
            this.helloService = helloService;
        }
    
        @Override
        public void selfIntroduction() {
            // 向大家打招呼
            helloService.sayHello("大家好!");
        }
    
    }

**5、Spring xml配置applicationContext-Constructor-Bean.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
           http://www.springframework.org/schema/beans/spring-beans.xsd">
        
        <bean id="helloService" class="com.jpeony.spring.common.HelloServiceImpl"/>
    
        
        <bean id="selfIntroductionService" class="com.jpeony.spring.constructor.SelfIntroductionServiceImpl">
            
            <constructor-arg ref="helloService"/>
        </bean>
    
    </beans>

**6、测试构造器注入bean**

package com.jpeony.spring;
    
    import com.jpeony.spring.constructor.SelfIntroductionService;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /**
     * 测试构造器注入（bean、字面量）
     *
     * @author yihonglei
     */
    public class ConstructorTest {
    
        /**
         * 造器注入Bean
         *
         * @author yihonglei
         */
        @Test
        public void testBean() {
            // 根据spring配置文件创建应用上下文
            ApplicationContext context =
                    new ClassPathXmlApplicationContext("applicationContext-Constructor-Bean.xml");
            // 从容器中获取bean
            SelfIntroductionService selfIntroductionService
                    = (SelfIntroductionService) context.getBean("selfIntroductionService");
            // 调用自我介绍
            selfIntroductionService.selfIntroduction();
        }
    
    }

**7、运行结果**

hello:大家好!

# 二 构造器注入字面量 #

**1、创建一个实体类**

package com.jpeony.spring.entity;
    
    /**
     * 个人信息（构造器注入使用）
     *
     * @author yihonglei
     */
    public class PersonConstructor {
    
        /**
         * 姓名
         */
        private String name;
        /**
         * 性别
         */
        private String sex;
        /**
         * 年龄
         */
        private int age;
        /**
         * 兴趣爱好
         */
        private String hobby;
    
        /**
         * 构造器注入时打开构造器--setter注入时注释掉构造器
         *
         * @param name
         * @param sex
         * @param age
         * @param hobby
         */
        public PersonConstructor(String name, String sex, int age, String hobby) {
            this.name = name;
            this.sex = sex;
            this.age = age;
            this.hobby = hobby;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getHobby() {
            return hobby;
        }
    
        public void setHobby(String hobby) {
            this.hobby = hobby;
        }
    }

**2、Spring xml配置applicationContext-Constructor-Constant.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
           http://www.springframework.org/schema/beans/spring-beans.xsd">
        
        <bean id="personConstructor" class="com.jpeony.spring.entity.PersonConstructor">
            
            <constructor-arg index="0" value="tom"/>
            <constructor-arg index="1" value="男"/>
            <constructor-arg index="2" value="26"/>
            <constructor-arg index="3" value="爱好女人,哈哈！开个玩笑！"/>
            
            
        </bean>
    
    </beans>

**3、测试构造器注入字面量**

package com.jpeony.spring;
    
    import com.jpeony.spring.entity.PersonConstructor;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /**
     * 测试构造器注入（bean、字面量）
     *
     * @author yihonglei
     */
    public class ConstructorTest {
    
        /**
         * 造器注入常量
         *
         * @author yihonglei
         */
        @Test
        public void testConstant() {
            // 根据spring配置文件创建应用上下文
            ApplicationContext context =
                    new ClassPathXmlApplicationContext("applicationContext-Constructor-Constant.xml");
            // 从容器中获取bean
            PersonConstructor person = (PersonConstructor) context.getBean("personConstructor");
            // 打印个人属性
            System.out.println(" 姓名: " + person.getName() +
                    " 性别: " + person.getSex() +
                    " 年龄: " + person.getAge() +
                    " 兴趣爱好: " + person.getHobby());
        }
    
    }

**4、运行结果**

姓名: tom 性别: 男 年龄: 26 兴趣爱好: 爱好女人,哈哈！开个玩笑！

[https_github.com_yihonglei_thinking-in-spring]: https://github.com/yihonglei/thinking-in-spring