Spring学习笔记之基于XML的Bean装配详解（二）

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原创最新推荐文章于 2026-03-22 01:13:28 发布 218 阅读 AI 写同款· GEO 优化 ›

【Spring】— Spring中Bean的装配方式在Spring实例化Bean的过程中，Spring首先会调用Bean的默认构造方法来实例化Bean对象，然后通过反射的方式调用setter()方法来注入属性值。在Spring中，尽管使用XML配置文件可以实现Bean的装配工作，但如果应用中有很多Bean，就会导致XML配置文件过于臃肿，给以后的维护和升级工作带来一定的困难。虽然使用注解的方式装配Bean在一定程度上减少了配置文件中的代码量，但是也有企业项目中是没有使用注解方式开发的，那么有没有什么办法既可以减少代码量，又能够实现Bean的装配呢？阅读详情

1、概述
IOC和DI的概念：

* IOC -- Inverse of Control，控制反转，将对象的创建权反转给Spring！！

* DI -- Dependency Injection，依赖注入，在Spring框架负责创建Bean对象时，动态的将依赖对象注入到Bean组件中！！

如果UserServiceImpl的实现类中有一个属性，那么使用Spring框架的IOC功能时，可以通过依赖注入把该属性的值传入进来！！

2、构造方法注入
构造方法注入就是利用bean的构造方法完成对bean中属性的赋值

创建Car实体类，提供有参构造方法Car.java

package com.day01.domain;
 
import java.io.Serializable;
 
/**
 * @ Author     ：ShaoWei Sun.
 * @ Date       ：Created in 10:34 2018/11/8
 */
public class Car implements Serializable {
    private String name;
    private Double price;
 
    public Car(String name, Double price) {
        this.name = name;
        this.price = price;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public Double getPrice() {
        return price;
    }
 
    public void setPrice(Double price) {
        this.price = price;
    }
 
    @Override
    public String toString() {
        return "Car{" +
                "name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}

//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">
 
    <!--构造方法注入-->
   <bean id="car" class="com.day01.domain.Car">
       <constructor-arg name="name" value="保时捷"></constructor-arg>
       <constructor-arg name="price" value="2000000.0"></constructor-arg>
   </bean>
 
</beans>

//tset
package com.day01.test;
 
import com.day01.dao.AddrDao;
import com.day01.dao.UserDao;
import com.day01.domain.Car;
import org.junit.Test;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;
 
/**
 * @ Author     ：ShaoWei Sun.
 * @ Date       ：Created in 19:30 2018/11/7
 */
public class TestIoC {
 
    @Test
    public void test6(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext2.xml");
        Car car = (Car) ac.getBean("car");
        System.out.println("car = " + car);
    }
 
}

结果：

3、set方法注入

set方法注入就是利用bean中属性的set方法对属性赋值。实体类中不用写getXXX方法

创建People.java实体类、提供属性的set方法、不用提供有参构造

package com.day01.domain;
 
import java.io.Serializable;
 
/**
 * @ Author     ：ShaoWei Sun.
 * @ Date       ：Created in 10:46 2018/11/8
 */
public class People implements Serializable {
    private String name;//提供对应的set方法
    private String address;
    private Car car;//对象属性
 
    public void setName(String name) {
        this.name = name;
    }
//    public String getName(){
//        return this.name;
//    }
 
    public void setAddress(String address) {
        this.address = address;
    }
 
    public void setCar(Car car) {
        this.car = car;
    }
 
    @Override
    public String toString() {
        return "People{" +
                "name='" + name + '\'' +
                ", address='" + address + '\'' +
                ", car=" + car +
                '}';
    }
}

//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">
 
    <!--构造方法注入-->
   <bean id="car" class="com.day01.domain.Car">
       <constructor-arg name="name" value="保时捷"></constructor-arg>
       <constructor-arg name="price" value="2000000.0"></constructor-arg>
   </bean>
 
    <!--set方法注入-->
    <bean id="people" class="com.day01.domain.People">
        <property name="name" value="小刚"></property>
        <property name="address" value="上海"></property>
        <property name="car" ref="car"></property>
    </bean>
</beans>

//tset
package com.day01.test;
 
import com.day01.dao.AddrDao;
import com.day01.dao.UserDao;
import com.day01.domain.Car;
import com.day01.domain.People;
import org.junit.Test;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;
 
import java.time.Period;
 
/**
 * @ Author     ：ShaoWei Sun.
 * @ Date       ：Created in 19:30 2018/11/7
 */
public class TestIoC {
 
 
    @Test
    public void test7(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext2.xml");
        People people = (People) ac.getBean("people");
        System.out.println("people = " + people);
    }
}

4、set方法注入其它写法
1）、p命名空间的写法

语法：p:属性名=”值“

p:对象属性名-ref = "bean的id"

applicationContext2.xml

约束：加这行：xmlns:p="http://www.springframework.org/schema/p"

<?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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
 
    <!--构造方法注入-->
   <bean id="car" class="com.day01.domain.Car">
       <constructor-arg name="name" value="保时捷"></constructor-arg>
       <constructor-arg name="price" value="2000000.0"></constructor-arg>
   </bean>
 
    <!--set方法注入-->
    <!--<bean id="people" class="com.day01.domain.People">-->
        <!--<property name="name" value="小刚"></property>-->
        <!--<property name="address" value="上海"></property>-->
        <!--<property name="car" ref="car"></property>-->
    <!--</bean>-->
    <!--p命名空间写法-->
    <bean id="people" class="com.day01.domain.People" p:name="小刚" p:address="北京" p:car-ref="car">
 
    </bean>
</beans>

//test
    @Test
    public void test7(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext2.xml");
        People people = (People) ac.getBean("people");
        System.out.println("people = " + people);
    }

2)、SpEL的写法

SpEL:Spring Expression Language

语法：

注入字符串：#{‘字符串’}

注入数字：#{数字}

注入其它对象：#{对象id}

applicationContext2.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"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
 
    <!--构造方法注入-->
   <bean id="car" class="com.day01.domain.Car">
       <constructor-arg name="name" value="保时捷"></constructor-arg>
       <constructor-arg name="price" value="2000000.0"></constructor-arg>
   </bean>
 
    <!--set方法注入-->
    <!--<bean id="people" class="com.day01.domain.People">-->
        <!--<property name="name" value="小刚"></property>-->
        <!--<property name="address" value="上海"></property>-->
        <!--<property name="car" ref="car"></property>-->
    <!--</bean>-->
    <!--p命名空间写法-->
    <!--<bean id="people" class="com.day01.domain.People" p:name="小刚" p:address="北京" p:car-ref="car">-->
    <!--</bean>-->
    <!--SpEL方法注入-->
    <bean id="people" class="com.day01.domain.People">
        <property name="name" value="#{'小刚'}"></property>
        <property name="address" value="#{'北京'}"></property>
        <property name="car" value="#{car}"></property>
    </bean>
</beans>

//test
    @Test
    public void test7(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext2.xml");
        People people = (People) ac.getBean("people");
        System.out.println("people = " + people);
    }

5、数组或List注入（重点）

当bean中的属性是List或数组类型。那么该怎么给List或数组注入值呢？数组和list注入的写法是一样的。

新建bean类、InfoBean.java

package com.day01.domain;
 
import java.util.List;
import java.util.Map;
import java.util.Set;
 
/**
 * @ Author     ：ShaoWei Sun.
 * @ Date       ：Created in 11:18 2018/11/8
 */
public class InfoBean {
    private List<String> list;
    private Set<String> set;
    private Map<String,String> map;
 
    public void setList(List<String> list){
        this.list = list;
    }
 
    public void setSet(Set<String> set) {
        this.set = set;
    }
 
    public void setMap(Map<String, String> map) {
        this.map = map;
    }
 
    @Override
    public String toString() {
        return "CollectionBean{" +
                "list=" + list +
                ", set=" + set +
                ", map=" + map +
                '}';
    }
}

//test
 
    @Test
    public void test8(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext2.xml");
        InfoBean infoBean = (InfoBean) ac.getBean("listId");
        System.out.println("infoBean = " + infoBean);
    }

<?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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
 
    <!--构造方法注入-->
   <bean id="car" class="com.day01.domain.Car">
       <constructor-arg name="name" value="保时捷"></constructor-arg>
       <constructor-arg name="price" value="2000000.0"></constructor-arg>
   </bean>
 
    <!--set方法注入-->
    <!--<bean id="people" class="com.day01.domain.People">-->
        <!--<property name="name" value="小刚"></property>-->
        <!--<property name="address" value="上海"></property>-->
        <!--<property name="car" ref="car"></property>-->
    <!--</bean>-->
    <!--p命名空间写法-->
    <!--<bean id="people" class="com.day01.domain.People" p:name="小刚" p:address="北京" p:car-ref="car">-->
    <!--</bean>-->
    <!--SpEL方法注入-->
    <bean id="people" class="com.day01.domain.People">
        <property name="name" value="#{'小刚'}"></property>
        <property name="address" value="#{'北京'}"></property>
        <property name="car" value="#{car}"></property>
    </bean>
 
 
    <bean id="listId" class="com.day01.domain.InfoBean">
        <!--list注入-->
        <property name="list">
            <list>
                <value>大罗</value>
                <value>小罗</value>
            </list>
        </property>
        <!--set集合注入-->
        <property name="set">
            <set>
                <value>鸠摩智</value>
                <value>无崖子</value>
            </set>
        </property>
        <!--map集合注入-->
        <property name="map">
            <map>
                <entry key="id" value="1"></entry>
                <entry key="username" value="张三"></entry>
            </map>
        </property>
    </bean>
</beans>

8、Properties的注入（重点）
有的时候，bean中的属性是Properties类型。那么该怎么给Properties类型的属性注入值呢？

Properties语法：

<prop>：表示一个键值对；

<prop>中的key表示键，在<prop></prop>中写的是值；

修改InfiBean.java，在其中添加一个Properties类型的属性并提供set方法：

package com.day01.domain;
 
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
 
/**
 * @ Author     ：ShaoWei Sun.
 * @ Date       ：Created in 11:18 2018/11/8
 */
public class InfoBean {
    private List<String> list;
    private Set<String> set;
    private Map<String,String> map;
    private Properties properties;
 
    public void setList(List<String> list){
        this.list = list;
    }
 
    public void setSet(Set<String> set) {
        this.set = set;
    }
 
    public void setMap(Map<String, String> map) {
        this.map = map;
    }
 
    public void setProperties(Properties properties) {
        this.properties = properties;
    }
 
    @Override
    public String toString() {
        return "CollectionBean{" +
                "list=" + list +
                ", set=" + set +
                ", map=" + map +
                ", properties=" + properties +
                '}';
    }
}

//xml
<!--preperties注入-->
        <property name="properties">
            <props>
                <prop key="id">2</prop>
                <prop key="name">小明</prop>
            </props>
        </property>

//test
    @Test
    public void test8(){
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext2.xml");
        InfoBean infoBean = (InfoBean) ac.getBean("listId");
        System.out.println("infoBean = " + infoBean);
    }

9、配置文件的分离
方式一：

在整个工程中有applicationContext.xml和applicationContext2.xml两个配置文件。可以把aplicationContext.xml看成一个总的配置文件，在其中包含applicaitonContext2.xml文件。修改applicationContext.xml内容如下：

<?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="userDao" class="com.day01.dao.impl.UserDaoImpl" init-method="init" destroy-method="destroy"></bean>
    <bean id="factory" class="com.day01.factory.Factory"></bean>
    <bean id="deptDao" factory-bean="factory" factory-method="create"></bean>
 
    <import resource="applicationContext2.xml"/>
</beans>

此时，创建IOC容器时，只需要加载applicationContext.xml即可，因为在applicationContext.xml引入了applicationContext2.xml文件，所以，applicationContext2.xml也会加载

方式二：

@Test
public void test4(){
    //创建Spring工厂（创建IOC容器）
    ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml","applicationContext2.xml");
    DeptDao deptDao = (DeptDao) ac.getBean("deptDao");
    deptDao.save();
 
}

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