Spring实战之Bean的后处理器操作示例

<?xml version="1.0" encoding="GBK"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns="http://www.springframework.org/schema/beans"
   xmlns:p="http://www.springframework.org/schema/p"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">
   <!-- 配置2个普通Bean实例 -->
   <bean id="steelAxe" class="org.crazyit.app.service.impl.SteelAxe"/>
   <bean id="chinese" class="org.crazyit.app.service.impl.Chinese"
      init-method="init" p:axe-ref="steelAxe" p:name="依赖注入的值"/>
   <!-- 配置Bean后处理器，可以无需指定id属性 -->
   <bean id="bp" class="org.crazyit.app.util.MyBeanPostProcessor"/>
</beans>

package org.crazyit.app.service;
public interface Axe
{
   public String chop();
}

package org.crazyit.app.service;
public interface Person
{
   public void useAxe();
}

package org.crazyit.app.service.impl;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.crazyit.app.service.*;
public class Chinese
  implements Person,InitializingBean
{
  private Axe axe;
  private String name;
  public Chinese()
  {
    System.out.println("Spring实例化主调bean：Chinese实例...");
  }
  public void setAxe(Axe axe)
  {
    this.axe = axe;
  }
  public void setName(String name)
  {
    System.out.println("Spring执行setName()方法注入依赖关系...");
    this.name = name;
  }
  public void useAxe()
  {
    System.out.println(name + axe.chop());
  }
  // 下面是两个生命周期方法
  public void init()
  {
    System.out.println("正在执行初始化方法 init...");
  }
  public void afterPropertiesSet() throws Exception
  {
    System.out.println("正在执行初始化方法 afterPropertiesSet...");
  }
}

package org.crazyit.app.service.impl;
import org.crazyit.app.service.*;
public class SteelAxe
   implements Axe
{
   public SteelAxe()
   {
      System.out.println("Spring实例化依赖bean：SteelAxe实例...");
   }
   public String chop()
   {
      return "钢斧砍柴真快";
   }
}

package org.crazyit.app.util;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.crazyit.app.service.*;
import org.crazyit.app.service.impl.*;
public class MyBeanPostProcessor
  implements BeanPostProcessor
{
  /**
   * 对容器中的Bean实例进行后处理
   * @param bean 需要进行后处理的原Bean实例
   * @param beanName 需要进行后处理的Bean的配置id
   * @return 返回后处理完成后的Bean
   */
  public Object postProcessBeforeInitialization
    (Object bean , String beanName)
  {
    System.out.println("Bean后处理器在初始化之前对"
      + beanName + "进行增强处理...");
    // 返回的处理后的Bean实例，该实例就是容器中实际使用的Bean
    // 该Bean实例甚至可与原Bean截然不同
    return bean;
  }
  public Object postProcessAfterInitialization
    (Object bean , String beanName)
  {
    System.out.println("Bean后处理器在初始化之后对"
      + beanName + "进行增强处理...");
    // 如果该Bean是Chinese类的实例
    if (bean instanceof Chinese)
    {
      // 修改其name成员变量
      Chinese c = (Chinese)bean;
      c.setName("疯狂iOS讲义");
    }
    return bean;
  }
}