Spring内部bean实例

Spring内部bean实例

在Spring框架中，一个bean仅用于一个特定的属性，这是提醒其声明为一个内部bean。内部bean支持setter注入“property”和构造器注入"constructor-arg“。
下面来看看一个详细的例子，演示使用 Spring 内部 bean 。 
package com.zyiz.netmon;

public class Customer 
{
	private Person person;

	public Customer(Person person) {
		this.person = person;
	}

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

	@Override
	public String toString() {
		return "Customer [person=" + person + "]";
	}
}
package com.zyiz.netmon;

public class Person 
{
	private String name;
	private String address;
	private int age;
	
	//getter and setter methods
	
	@Override
	public String toString() {
		return "Person [address=" + address + ", 
                               age=" + age + ", name=" + name + "]";
	}	
}
很多时候，可以使用 'ref' 属性来引用“Person” bean到“Customer” Bean，person的属性如下： 
<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-2.5.xsd">

	<bean id="CustomerBean" class="com.zyiz.netmon.Customer">
		<property name="person" ref="PersonBean" />
	</bean>

	<bean id="PersonBean" class="com.zyiz.netmon.Person">
		<property name="name" value="zyiz" />
		<property name="address" value="address1" />
		<property name="age" value="28" />
	</bean>
	
</beans>
在一般情况下，引用这样也没有问题，但由于“zyiz” persion bean 只用于Customer bean，这是更好地声明 “zyiz” person 作为一个内部 bean，如下： 
<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-2.5.xsd">

	<bean id="CustomerBean" class="com.zyiz.netmon.Customer">
		<property name="person">
			<bean class="com.zyiz.netmon.Person">
				<property name="name" value="zyiz" />
				<property name="address" value="address1" />
				<property name="age" value="28" />
			</bean>
		</property>
	</bean>
</beans>
内部 bean 也支持构造器注入如下： 
<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-2.5.xsd">

	<bean id="CustomerBean" class="com.zyiz.netmon.Customer">
		<constructor-arg>
			<bean class="com.zyiz.netmon.Person">
				<property name="name" value="zyiz" />
				<property name="address" value="address1" />
				<property name="age" value="28" />
			</bean>
		</constructor-arg>
	</bean>
</beans>
注意：
id 或 name 值在bean类是没有必要以一个内部 bean 呈现，它会简单地忽略Spring容器。

执行结果： 

package com.zyiz.netmon;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App 
{
    public static void main( String[] args )
    {
    	ApplicationContext context = 
    	  new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"});

    	Customer cust = (Customer)context.getBean("CustomerBean");
    	System.out.println(cust);
     
    }
}

输出结果： 

Customer [person=Person [address=address1, age=28, name=zyiz]]


目录

Spring快速入门

Spring自动装配Bean

Spring JDBC支持

Spring JavaConfig

Spring 依赖注入(DI)

Spring Bean基础

Spring表达式语言

Spring自动组件扫描

Spring AOP (面向方面编程)

Spring AOP + AspectJ框架

Spring Hibernate支持

Spring E-mail支持

Spring与其它Web框架集成