Spring如何继承Bean？详细示例

1. 在Spring继承Bean

通过使用bean的parent属性, 我们可以指定bean之间的继承关系。在这种情况下, 父bean值将被继承到当前bean。

让我们看一下继承bean的简单示例。

Employee.java

此类包含三个属性, 三个构造函数和用于显示值的show()方法。

package com.srcmini;

public class Employee {
private int id;
private String name;
private Address address;
public Employee() {}

public Employee(int id, String name) {
	super();
	this.id = id;
	this.name = name;
}
public Employee(int id, String name, Address address) {
	super();
	this.id = id;
	this.name = name;
	this.address = address;
}

void show(){
	System.out.println(id+" "+name);
	System.out.println(address);
}

}

Address.java

package com.srcmini;

public class Address {
private String addressLine1, city, state, country;

public Address(String addressLine1, String city, String state, String country) {
	super();
	this.addressLine1 = addressLine1;
	this.city = city;
	this.state = state;
	this.country = country;
}
public String toString(){
	return addressLine1+" "+city+" "+state+" "+country;
}

}

applicationContext.xml

<?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-3.0.xsd">

<bean id="e1" class="com.srcmini.Employee">
<constructor-arg value="101"></constructor-arg>
<constructor-arg  value="Sachin"></constructor-arg>
</bean>

<bean id="address1" class="com.srcmini.Address">
<constructor-arg value="21, Lohianagar"></constructor-arg>
<constructor-arg value="Ghaziabad"></constructor-arg>
<constructor-arg value="UP"></constructor-arg>
<constructor-arg value="USA"></constructor-arg>
</bean>

<bean id="e2" class="com.srcmini.Employee" parent="e1">
<constructor-arg ref="address1"></constructor-arg>
</bean>

</beans>

Test.java

此类从applicationContext.xml文件获取Bean并调用show方法。

package com.srcmini;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

public class Test {
public static void main(String[] args) {
	Resource r=new ClassPathResource("applicationContext.xml");
	BeanFactory factory=new XmlBeanFactory(r);
	
	Employee e1=(Employee)factory.getBean("e2");
	e1.show();
	
}
}

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