【Spring基础】IOC使用Setter依赖注入

雨点打透心脏的1/2处 2022-06-03 00:50 172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）

如果Spring使用XML配置形式，最常用有两种依赖注入方式：**setter注入和构造器注入。**

这里主要讨论基于setter方法的依赖注入。

# 一 Setter注入Bean #

**1、创建一个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、创建一个SelfIntroductionService(自我介绍)接口**

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

**4、SelfIntroductionServiceImpl实现类**

package com.jpeony.spring.setter;
    
    import com.jpeony.spring.common.HelloService;
    
    /**
     * @author yihonglei
     */
    public class SelfIntroductionServiceImpl implements SelfIntroductionService {
        private HelloService helloService;
    
        /**
         * setter方式注入Bean
         */
        public void setHelloService(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-Setter-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.setter.SelfIntroductionServiceImpl">
            <property name="helloService" ref="helloService"/>
        </bean>
    
    </beans>

**6. 测试setter注入Bean**

package com.jpeony.spring;
    
    import com.jpeony.spring.setter.SelfIntroductionService;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /**
     * 测试setter注入(bean、字面量、集合)
     *
     * @author yihonglei
     */
    public class SetterTest {
    
        /**
         * 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-Setter-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!

总结:

自我介绍类中SelfIntroductionServiceImpl，通过set方法注入bean,

在XML中通过<property name="helloService" ref="helloService"/>指明依赖关系。

# 二 Setter方法注入字面量 #

setter方法除了上面应用于注入bean之外，还可以用于注入字面量。

**1、创建一个实体类**

package com.jpeony.spring.entity;
    
    /**
     * 个人信息（setter注入使用）
     *
     * @author yihonglei
     */
    public class PersonSetter {
    
        /**
         * 姓名
         */
        private String name;
        /**
         * 性别
         */
        private String sex;
        /**
         * 年龄
         */
        private int age;
        /**
         * 兴趣爱好
         */
        private String 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配置applicationContext-Setter-Constant.xml**

**3、测试setter注入字面量**

package com.jpeony.spring;
    
    import com.jpeony.spring.entity.PersonSetter;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /**
     * 测试setter注入(bean、字面量、集合)
     *
     * @author yihonglei
     */
    public class SetterTest {
    
        /**
         * 注入字面量
         *
         * @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-Setter-Constant.xml");
            // 从容器中获取bean
            PersonSetter person = (PersonSetter) context.getBean("personSetter");
            // 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！

# 三 Setter方法注入集合 #

setter方法还可以用来注入集合，直接看看实例。

**1、创建集合类**

package com.jpeony.spring.entity;
    
    import java.util.Arrays;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    /**
     * Spring 注入集合
     *
     * @author yihonglei
     */
    public class Collection {
        private Set<String> set;
        private List<String> list;
        private Map<String, String> map;
        private String[] array;
    
        public Set<String> getSet() {
            return set;
        }
    
        public void setSet(Set<String> set) {
            this.set = set;
        }
    
        public List<String> getList() {
            return list;
        }
    
        public void setList(List<String> list) {
            this.list = list;
        }
    
        public Map<String, String> getMap() {
            return map;
        }
    
        public void setMap(Map<String, String> map) {
            this.map = map;
        }
    
        public String[] getArray() {
            return array;
        }
    
        public void setArray(String[] array) {
            this.array = array;
        }
    
        @Override
        public String toString() {
            return "Collection{" +
                    "  set=" + set +
                    ", list=" + list +
                    ", map=" + map +
                    ", array=" + Arrays.toString(array) +
                    '}';
        }
    }

**2、Spring xml配置applicationContext-Setter-List.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="collection" class="com.jpeony.spring.collection.Collection">
            
            <property name="set">
                <set>
                    <value>set1</value>
                    <value>set2</value>
                    <value>set3</value>
                </set>
            </property>
            
            <property name="list">
                <list>
                    <value>list1</value>
                    <value>list2</value>
                    <value>list3</value>
                </list>
            </property>
            
            <property name="array">
                <list>
                    <value>array1</value>
                    <value>array1</value>
                    <value>array1</value>
                </list>
            </property>
            
            <property name="map">
                <map>
                    <entry key="key1" value="map1"></entry>
                    <entry key="key2" value="map2"></entry>
                    <entry key="key3" value="map3"></entry>
                </map>
            </property>
        </bean>
    
    </beans>

**3、测试Setter注入集合**

package com.jpeony.spring;
    
    import com.jpeony.spring.entity.Collection;
    import org.junit.Test;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    /**
     * 测试setter注入(bean、字面量、集合)
     *
     * @author yihonglei
     */
    public class SetterTest {
    
        /**
         * 注入集合
         *
         * @author yihonglei
         */
        @Test
        public void testList() {
            // 根据spring配置文件创建应用上下文
            ApplicationContext context =
                    new ClassPathXmlApplicationContext("applicationContext-Setter-List.xml");
            // 从容器中获取bean
            Collection collection = (Collection) context.getBean("collection");
            // 打印个人属性
            System.out.println("Setter注入集合:" + collection.toString());
        }
    
    }

**4、运行结果**

Setter注入集合:Collection\{  set=\[set1, set2, set3\], list=\[list1, list2, list3\], map=\{key1=map1, key2=map2, key3=map3\}, array=\[array1, array1, array1\]\}

# 四 总结 #

Spring setter注入可用于注入bean、字面量、集合；

如果是新项目，建议使用Spring注解，因为一堆一堆的xml不好维护，同时功能也不如注解强大。

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