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

  1. 注入简单值
  2. 注入引用
  3. 注入内部Bean
  4. 装配集合
  5. 装配空值
  6. 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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