Spring框架学习（3）：spring属性配置的细节

本篇文章主要讲一下Spring属性配置的细节

一、Bean之间的引用

首先我们知道，组成应用程序的Bean经常需要相互协助以完成应用程序的功能，要使Bean能够相互访问就必须在Bean配置文件中指定对Bean的引用。有两种方法使Bean之间构成引用的关系

1.在配置文件中通过ref属性为Bean的属性或构造器参数指定对Bean的引用

首先写两个类Person和Address

package beans;public class Person {private String name;private Address address;public String getName() {return name;}public void setName(String name) {this.name = name;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}@Overridepublic String toString() {return "Person [name=" + name + ", address=" + address + "]";}}

package beans;public class Address {private String city;private String street;public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getStreet() {return street;}public void setStreet(String street) {this.street = street;}@Overridepublic String toString() {return "Address [city=" + city + ", street=" + street + "]";}}

然后在配置文件中配置他们的引用关系

 

写一个main函数测试一下

 

2.在属性或者构造器中包含Bean的声明，即内部Bean，外部的其他Bean无法访问到该内部Bean。

在配置文件中配置他们的引用关系，其他不改变

<?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="person" class="beans.Person"><property name="name" value="Tom"></property><property name="address"><bean class="beans.Address"><property name="city" value="GuangZhou"></property><property name="street" value="Shangxiajiu"></property></bean></property></bean></beans>

二、Bean属性中带有特殊字符

当property属性的value值带有特殊字符，例如<>时，可以使用以下方法配置

<bean id="person" class="beans.Person"><property name="name" value="Tom"></property><property name="address"><bean class="beans.Address"><property name="city"><value><![CDATA[<GuangZhou>]]></value></property><property name="street" value="Shangxiajiu"></property></bean></property></bean>

三、为级联属性赋值

<bean id="person" class="beans.Person"><property name="name" value="Tom"></property><property name="address" ref="address"></property><property name="address.city" value="ShangHai"></property></bean>

需要注意的是，属性需要先初始化才可以为级联属性赋值

四、为集合属性赋值

配置List属性：

修改一下Person类，将地址改为List

package beans;import java.util.List;public class Person {private String name;private List<Address> addresses;  public String getName() {return name;}public void setName(String name) {this.name = name;}public List<Address> getAddresses() {return addresses;}public void setAddresses(List<Address> addresses) {this.addresses = addresses;}@Overridepublic String toString() {return "Person [name=" + name + ", addresses=" + addresses + "]";}}

在配置文件中：

<?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="address1" class="beans.Address"><property name="city" value="GuangZhou"></property><property name="street" value="Shangxiajiu"></property></bean><bean id="address2" class="beans.Address"><property name="city" value="GuangZhou"></property><property name="street" value="Gongyuanqian"></property></bean><bean id="person" class="beans.Person"><property name="name" value="Tom"></property><property name="addresses"><list><ref bean="address1"/><ref bean="address2"/></list></property></bean></beans>

配置Array属性与List差不多

配置Map属性：

修改一下Person类

package beans;import java.util.List;import java.util.Map;public class Person {private String name;private Map<String, Address> addresses;public String getName() {return name;}public void setName(String name) {this.name = name;}public Map<String, Address> getAddresses() {return addresses;}public void setAddresses(Map<String, Address> addresses) {this.addresses = addresses;}@Overridepublic String toString() {return "Person [name=" + name + ", addresses=" + addresses + "]";}}

修改配置文件：

<?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="address1" class="beans.Address"><property name="city" value="GuangZhou"></property><property name="street" value="Shangxiajiu"></property></bean><bean id="address2" class="beans.Address"><property name="city" value="GuangZhou"></property><property name="street" value="Gongyuanqian"></property></bean><bean id="person" class="beans.Person"><property name="name" value="Tom"></property><property name="addresses"><map><entry key="AA" value-ref="address1"></entry><entry key="BB" value-ref="address2"></entry></map></property></bean></beans>

五、通过p命名空间为bean属性赋值

需要先导入p命名空间，在配置文件的页面点NameSpaces，然后勾选p命名空间即可，p命名空间可以帮助我们更快捷得配置bean

配置文件如下：

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"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"><bean id="address" class="beans.Address"><property name="city" value="GuangZhou"></property><property name="street" value="Shangxiajiu"></property></bean><bean id="person" class="beans.Person"p:name="Tom" p:address-ref="address"></bean></beans>