5.Spring给bean的属性赋值(配置文件)

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在Spring的容器配置文件中给bean的属性赋值

DI(依赖注入)的分类：

  1. 设值注入：调用bean对象的set()方法，在创建对象之后给属性赋值
  2. 构造注入：调用bean对象的构造方法，创建对象的同时给属性赋值

1. 设值注入

1.1 简单类型：String和Java的基本数据类型

创建实体类Student

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public class Student {

	public String name;
	public int age;
	
	public void setName(String name) {
		System.out.println("setName");
		this.name = name;
	}

	public void setAge(int age) {
		System.out.println("setAge");
		this.age = age;
	}
	
	public void setAddress(String address) {
		System.out.println("setAddress");
	}

	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + "]";
	}	
}
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<?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">
	
    <!-- 设值注入 -->
	<!-- 注册Student bean对象 -->
	<bean id="myStudent" class="com.node.ba01.Student">
		<!-- 给bean的属性赋值，使用设值注入，简单类型的属性使用value
				name:bean的属性名
				value:简单类型的属性值
		 -->
		<property name="name" value="张三" />
		<property name="age" value="20" />
		<property name="address" value="北京" />
	</bean>

</beans>

1.2 给引用类型的属性赋值

实体类Student

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public class Student {

	private String name;
	private int age;
	
    //引用类型的属性
	private School school;
	
	public void setSchool(School school) {
		this.school = school;
	}

	public void setName(String name) {
		System.out.println("setName");
		this.name = name;
	}

	public void setAge(int age) {
		System.out.println("setAge");
		this.age = age;
	}
	
	public void setAddress(String address) {
		System.out.println("setAddress");
	}

	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + ", school=" + school + "]";
	}	
}

创建实体类School

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public class School {

	private String name;
	private String address;
	
	public void setName(String name) {
		this.name = name;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	
	@Override
	public String toString() {
		return "School [name=" + name + ", address=" + address + "]";
	}	
}
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<?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">

    <!-- 设值注入 -->
	<!-- 注册School bean对象 -->
	<bean id="mySchool" class="com.node.ba02.School">
		<property name="name" value="北京大学" />
		<property name="address" value="海淀区" />
	</bean>
	
	<!-- 注册Student bean对象 -->
	<bean id="myStudent" class="com.node.ba02.Student">
		<!-- 给bean的属性赋值，使用设值注入，简单类型的属性使用value
				name:bean的属性名
				value:简单类型的属性值
		 -->
		<property name="name" value="张三" />
		<property name="age" value="20" />
		<property name="address" value="北京" />
		
		<!-- 给引用类型的属性赋值，使用ref属性给引用类型的属性赋值 -->
		<property name="school" ref="mySchool" />
		
	</bean>
	
	<!-- 使用ref子标签给引用类型的属性赋值 -->
	<bean id="myStudent2" class="com.node.ba02.Student">
		<property name="name" value="李四" />
		<property name="age" value="20" />
		<property name="address" value="北京" />
		
		<!-- 给引用类型的属性赋值，使用ref子标签 -->
		<property name="school">
			<ref bean="mySchool"/>
		</property>
	</bean>
</beans>

2. 构造注入

实体类Student

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public class Student {

	private String name;
	private int age;
	
	//引用类型的属性
	private School school;
	
	public Student(String myName, int myAge, School mySchool) {
		this.name=myName;
		this.age=myAge;
		this.school=mySchool;
	}
	
	public void setSchool(School school) {
		this.school = school;
	}

	public void setName(String name) {
		System.out.println("setName");
		this.name = name;
	}

	public void setAge(int age) {
		System.out.println("setAge");
		this.age = age;
	}
	
	public void setAddress(String address) {
		System.out.println("setAddress");
	}

	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + ", school=" + school + "]";
	}	
}
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<?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">
	
	<!-- 使用构造注入，调用bean的有参数的构造方法，创建对象的同时给属性赋值 -->
	<!-- 使用name属性 -->
	<bean id="myStudent" class="com.node.ba03.Student">
		<!-- 
			name:构造方法的形参名
			value:简单类型的属性值
			ref:引用类型的属性名
		 -->
		 <constructor-arg name="myName" value="张三" />
		 <constructor-arg name="myAge" value="26" />
		 <constructor-arg name="mySchool" ref="mySchool" />
	</bean>
	
	<!-- 使用index属性，表示参数的索引位置，从0开始 -->
	<bean id="myStudent2" class="com.node.ba03.Student">
		<constructor-arg index="0" value="张三" />
		 <constructor-arg index="1" value="28" />
		 <constructor-arg index="2" ref="mySchool" />
	</bean>

	<!-- 注册School对象 -->
	<bean id="mySchool" class="com.node.ba03.School">
		<property name="name" value="实验小学" />
		<property name="address" value="海淀区" />
	</bean>
</beans>

3. 集合类型的属性赋值

对Array, List, Set, Map, Properties类型的属性赋值

创建实体类MyCollections

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import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class MyCollections {
	
	private String[] myStrs;
	private List<Student> myList;
	private Set<String> mySet;
	private Map<String, Integer> myMap;
	private Properties myProps;
	
	//复杂的集合类型
	private List<Map<String, String>> myListMap;
	
	public List<Map<String, String>> getMyListMap() {
		return myListMap;
	}
	public void setMyListMap(List<Map<String, String>> myListMap) {
		this.myListMap = myListMap;
	}
	public String[] getMyStrs() {
		return myStrs;
	}
	public void setMyStrs(String[] myStrs) {
		this.myStrs = myStrs;
	}
	public List<Student> getMyList() {
		return myList;
	}
	public void setMyList(List<Student> myList) {
		this.myList = myList;
	}
	public Set<String> getMySet() {
		return mySet;
	}
	public void setMySet(Set<String> mySet) {
		this.mySet = mySet;
	}
	public Map<String, Integer> getMyMap() {
		return myMap;
	}
	public void setMyMap(Map<String, Integer> myMap) {
		this.myMap = myMap;
	}
	public Properties getMyProps() {
		return myProps;
	}
	public void setMyProps(Properties myProps) {
		this.myProps = myProps;
	}
	@Override
	public String toString() {
		return "MyCollections [myStrs=" + Arrays.toString(myStrs) + ", myList=" + myList + ", mySet=" + mySet
				+ ", myMap=" + myMap + ", myProps=" + myProps + ", myListMap=" + myListMap + "]";
	}
}
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<?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">
	
	<!-- 注册MyCollections -->
	<bean id="myCollections" class="com.node.ba04.MyCollections">
		<!-- 设值注入 -->
		<!-- Array -->
		<property name="myStrs">
			<array>
				<value>北京</value>
				<value>上海</value>
			</array>
		</property>
		
		<!-- List -->
		<property name="myList">
			<list>
				<ref bean="myStudent" />
				<ref bean="myStudent2" />
			</list>
		</property>
		
		<!-- Map -->
		<property name="myMap">
			<map>
				<!-- 
					key:map的key的值
					value:map的value
				 -->
				<entry key="height" value="170"></entry>
				<entry key="weight" value="65"></entry>
			</map>
		</property>
		
		<!-- Set -->
		<property name="mySet">
			<set>
				<value>海淀区</value>
				<value>大兴区</value>
			</set>
		</property>
		
		<!-- Properties -->
		<property name="myProps">
			<props>
				<!-- 
					key:key
					value:开始标签和结束标签之间
				 -->
				<prop key="tel">010-123456</prop>
				<prop key="address">大兴</prop>
			</props>
		</property>
		
		<!-- List<Map<String, String>> -->
		<property name="myListMap">
			<list>
				<map>
					<entry key="height" value="170cm"></entry>
					<entry key="weight" value="65kg"></entry>
				</map>
				
				<map>
					<entry key="city" value="石家庄"></entry>
					<entry key="privince" value="河北"></entry>
				</map>
			</list>
		</property>
	</bean>

	<bean id="myStudent" class="com.node.ba04.Student">
		 <constructor-arg name="myName" value="张三" />
		 <constructor-arg name="myAge" value="26" />
		 <constructor-arg name="mySchool" ref="mySchool" />
	</bean>
	
	<bean id="myStudent2" class="com.node.ba04.Student">
		<constructor-arg index="0" value="张三" />
		 <constructor-arg index="1" value="28" />
		 <constructor-arg index="2" ref="mySchool" />
	</bean>

	<bean id="mySchool" class="com.node.ba04.School">
		<property name="name" value="实验小学" />
		<property name="address" value="海淀区" />
	</bean>
</beans>
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<?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">
	
	<!-- 注册MyCollections -->
	<bean id="myCollections" class="com.node.ba05.MyCollections">
		<!-- 设值注入 -->
		<!-- Array可以使用array,也可以使用list -->
		<property name="myStrs">
			<list>
				<value>北京-array</value>
				<value>上海-array</value>
			</list>
		</property>
		<!--  Array也可以使用value。value使用,分隔的多个值 -->
		<property name="myStrs" value="河北，山东">
		</property>
		
		<!-- List -->
		<!-- 该List只有一个元素 -->
		<property name="myList" ref="myStudent">
			
		</property>
		
		<!-- Set -->
		<!-- 该Set只有一个元素 -->
		<property name="mySet" value="海淀区-set,大兴区-set">
			
		</property>
</beans>

4. 引用类型的自动注入

对于引用类型属性的注入，也可不在配置文件中显式的明确注入，可以通过为bean标签设置autowire属性值，为引用类型的属性进行隐式自动注入(默认不自动注入引用类型属性)。

可以分为两种：

  1. byName: 根据名称自动注入

  2. byType: 根据类型自动注入

4.1 byName

当配置文件中被调用者Bean的id值与代码中调用者Bean类的属性名相同时，可以使用byName方式，让容器自动将被调用者Bean注入给调用者Bean。容器是通过调用者的Bean类的属性名与配置文件的被调用者Bean的id进行比较而实现自动注入的。