Spring入门（4）-注入Bean属性
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>
