Spring之替换Bean的返回结果,替换Bean的方法实例

Spring是一个非常强悍的框架+容器,其中有代理模式(动态代理模式)的极致体现。下面是两个比较让人感觉精彩的代码使用，重点关注main方法中的ClassPathXMlApplicationContext对象的实例化代码，替换对象方法的代码以及替换对象方法返回值的代码。具体的支持类有ASM、CGLIB、以及Spring3.0 CORE JAR.

代码如下:

MainMethod.java

 

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainMethod {

	private static StudentBiz studentBiz;

	public void setStudentBiz(StudentBiz studentBiz) {

		MainMethod.studentBiz = studentBiz;

	}

	public static void main(String[] args) {

		new ClassPathXmlApplicationContext("applicationContext.xml");

		System.out.println(studentBiz.getStudent().getName());

		studentBiz.printMsg();

	}

}

SbMethodReplacer.java

import java.lang.reflect.Method;

import org.springframework.beans.factory.support.MethodReplacer;

public class SbMethodReplacer implements MethodReplacer{

	@Override

	public Object reimplement(Object obj, Method method, Object[] args)

			throws Throwable {

		System.out.println("Hi world!!");

		return null;

	}

}

Student.java

public class Student {

	private String name;

	public String getName() {

		return name;

	}

	public void setName(String name) {

		this.name = name;

	}

}

StudentBiz.java

public interface StudentBiz {

	public Student getStudent();

	public void printMsg();

}

StudentBizImpl.java

public class StudentBizImpl implements StudentBiz {

	@Override

	public Student getStudent() {

		return null;

	}

	@Override

	public void printMsg() {

		System.out.println("hello world!!");

	}

}

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 name="sbMethodReplacer" class="SbMethodReplacer"/>

	<bean name="student" class ="Student">

		<property name="name"><value>anyone</value></property>

	</bean>

	<bean name="studentbiz" class="StudentBizImpl">

		<lookup-method name="getStudent" bean="student"/>

		<replaced-method name="printMsg" replacer="sbMethodReplacer"/>

	</bean>

	<bean name="mainM" class="MainMethod">

		<property name="studentBiz" ref="studentbiz"/>

	</bean>

</beans>