Spring入门（4）-注入Bean属性

本文介绍如何注入Bean属性，包括简单属性、引用、内部Bean、注入集合等。

0. 目录

注入简单值
注入引用
注入内部Bean
装配集合
装配空值
使用命名空间p

1. 注入简单值

前面介绍过注入简单值的例子，在这里回顾一下。

package com.chzhao.springtest;

public class PersonBll implements IPersonBll {

	private String id;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public void show() {
		System.out.println(id);
	}

	public void addPerson(Person p) {
		System.out.println("add person: " + p.getName());
	}
}

<?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  name="PersonBll" class="com.chzhao.springtest.PersonBll" >
		<property name="id" value="abcdefg"></property>
	</bean> 
</beans>

2. 注入引用

大部分情况下简单值不能满足要求，往往是需要一个引用。

package com.chzhao.springtest;

public class PersonBll implements IPersonBll {

	private Person person;

	public Person getPerson() {
		return person;
	}

	public void setPerson(Person person) {
		this.person = person;
	}

	public void show() {
		System.out.println(this.person.getName());
	}

	public void addPerson(Person p) {
		System.out.println("add person: " + p.getName());
	}
}

<?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 name="p" class="com.chzhao.springtest.Person">
		<property name="name" value="老王" />
	</bean>
	<bean  name="PersonBll" class="com.chzhao.springtest.PersonBll" >
		<property name="person" ref="p"></property>
	</bean> 
</beans>

3. 注入内部Bean

除了上面这种方式之外，也可以把Bean定义为内部Bean，防止别的类调用。

<?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  name="PersonBll" class="com.chzhao.springtest.PersonBll" >
		<property name="person" >
			<bean name="p" class="com.chzhao.springtest.Person">
				<property name="name" value="老王" />
			</bean>
		</property>
	</bean> 
</beans>

4. 装配集合

Spring也支持装配集合，支持的集合如下：

集合元素	用途
list	装配list类型的值，允许重复
set	装配set类型的值，不允许重复
map	装配map类型的值
props	装配properties类型的值，名称和值都必须是String

4.1. 装配list或set

装配list和set差不多，只是set元素不能重复

package com.chzhao.springtest;

import java.util.List;

public class PersonBll implements IPersonBll {

	private List<String> idList;

	public List<String> getIdList() {
		return idList;
	}

	public void setIdList(List<String> idList) {
		this.idList = idList;
	}

	public void show() {
		for (String s : this.idList) {
			System.out.println(s);
		}
	}

	public void addPerson(Person p) {
		System.out.println("add person: " + p.getName());
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:p="http://www.springframework.org/schema/p"
	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  name="PersonBll" class="com.chzhao.springtest.PersonBll">
		<property name="idList">
			<list>
				<value>wang</value>
				<value>zhao</value>
				<value>li</value>
			</list>
		</property>
	</bean> 
</beans>

4.2. 装配map

package com.chzhao.springtest;

import java.util.Map;

public class PersonBll implements IPersonBll {

	private Map<Integer, Person> pmap;

	public Map<Integer, Person> getPmap() {
		return pmap;
	}

	public void setPmap(Map<Integer, Person> pmap) {
		this.pmap = pmap;
	}

	public void show() {
		for (Integer i : this.pmap.keySet()) {
			System.out.println(i);
			System.out.println(this.pmap.get(i).getName());
		}
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:p="http://www.springframework.org/schema/p"
	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 name="laowang" class="com.chzhao.springtest.Person">
		<property name="name" value="老王" />
	</bean>
	<bean name="laoli" class="com.chzhao.springtest.Person">
		<property name="name" value="老李" />
	</bean>
	<bean  name="PersonBll" class="com.chzhao.springtest.PersonBll">
		<property name="pmap">
			<map>
				<entry key="1" value-ref="laowang"></entry>
				<entry key="2" value-ref="laoli"></entry>
			</map>
		</property>
	</bean> 
</beans>

MAP的属性包括

属性	用途
key	key为String
key-ref	key为引用
value	值为string
value-ref	值为引用

4.3. 装配properties

package com.chzhao.springtest;

import java.util.Properties;

public class PersonBll implements IPersonBll {

	private Properties pro;

	public Properties getPro() {
		return pro;
	}

	public void setPro(Properties pro) {
		this.pro = pro;
	}

	public void show() {
		System.out.println(this.pro.get("1"));
		System.out.println(this.pro.get("2"));
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:p="http://www.springframework.org/schema/p"
	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  name="PersonBll" class="com.chzhao.springtest.PersonBll">
		<property name="pro">
			<props>
				<prop key="1">老王</prop>
				<prop key="2">老李</prop>
			</props>
		</property>
	</bean> 
</beans>

5. 装配空值

也可以把属性赋值为空

package com.chzhao.springtest;

public class PersonBll implements IPersonBll {

	private String id;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public void show() {
		if (this.id == null) {
			System.out.println("null");
		} else {
			System.out.println(this.id);
		}
	}
}

<?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  name="PersonBll" class="com.chzhao.springtest.PersonBll">
		<property name="id" ><null></null></property>
	</bean> 
</beans>

也可以定义为

<?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  name="PersonBll" class="com.chzhao.springtest.PersonBll">
		<property name="id" ><null/></property>
	</bean> 
</beans>

6. 使用命名空间p

Spring提供了命名空间p简化Bean属性定义，需要在XML中增加

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

package com.chzhao.springtest;

public class PersonBll implements IPersonBll {

	private String id;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	private Person person;

	public Person getPerson() {
		return person;
	}

	public void setPerson(Person person) {
		this.person = person;
	}

	public void show() {
		System.out.println(this.person.getName());
		System.out.println(this.id);
	}

	public void addPerson(Person p) {
		System.out.println("add person: " + p.getName());
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:p="http://www.springframework.org/schema/p"
	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 name="p" class="com.chzhao.springtest.Person">
		<property name="name" value="老王" />
	</bean>
	<bean  name="PersonBll" class="com.chzhao.springtest.PersonBll" 
p:person-ref = "p" p:id="0000">
	</bean> 
</beans>

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原文地址：https://www.cnblogs.com/wardensky/p/4198733.html