【spring bean】spring中bean的懒加载和depends-on属性设置

项目结构如下：

ResourceBean.java代码：

 package com.it.res;

 import java.io.File;

 import java.io.FileNotFoundException;

 import java.io.FileOutputStream;

 import java.io.IOException;

 public class ResourceBean {

     private FileOutputStream out;

     private File file;

     public void init(){

         System.out.println("初始化的方法！！！！！--->加载资源");

         try {

             this.out = new FileOutputStream(file);

         } catch (FileNotFoundException e) {

             e.printStackTrace();

         }

     }

     public void destroy(){

         System.out.println("销毁的方法！！！--->清理内存");

         try {

             out.close();

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

     public FileOutputStream getOut(){

         return out;

     }

     public void setFile(File file){

         this.file=file;

     }

 }

DependentBean.java代码：

 package com.it.res;

 import java.io.IOException;

 public class DependentBean {

     ResourceBean bean;

     public void write(String ss){

         System.out.println("写入资源");

         try {

             bean.getOut().write(ss.getBytes());

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

     public void init(){

         System.out.println("depen--->初始化");

         try {

             bean.getOut().write("depen---->初始化".getBytes());

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

     public void destroy(){

         System.out.println("depen--->销毁");

         try {

             bean.getOut().write("depen--->销毁".getBytes());

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

     public ResourceBean getBean() {

         return bean;

     }

     //设置注入

     public void setBean(ResourceBean bean) {

         this.bean = bean;

     }

 }

resWrite.xml代码：

 <?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:context="http://www.springframework.org/schema/context"

 xsi:schemaLocation="

 http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

 http://www.springframework.org/schema/context                http://www.springframework.org/schema/context/spring-context-3.0.xsd">

     <!-- init-method  指定初始化方法，在构造器注入和setter注入完毕后执行。    destroy-method   只有“singleton”作用域能销毁，“prototype”作用域的一定不能，其他作用域不一定能    lazy-init="true"表示懒加载，不提前初始化Bean，而是只有在真正使用时才创建及初始化Bean-->

      <bean id="resourceBean" class="com.it.res.ResourceBean" init-method="init" destroy-method="destroy" lazy-init="true">

          <property name="file" value="F:/test/a.txt"> </property><!-- Spring容器能自动把字符串转换为java.io.File   -->

      </bean>

     <!-- 指定depends-on  则resourceBean会在dependentBean之前初始化，在dependentBean销毁之后销毁-->

     <bean id="dependentBean" class="com.it.res.DependentBean" init-method="init" destroy-method="destroy" depends-on="resourceBean">

         <property name="bean" ref="resourceBean"></property>

     </bean>

 </beans>  

测试类Test.java代码：

 package com.it.res;

 import org.springframework.context.support.FileSystemXmlApplicationContext;

 public class Test {

     @org.junit.Test

     public void testDepen(){

         FileSystemXmlApplicationContext app = new FileSystemXmlApplicationContext("resources/resWrite.xml");

         //一定要注册销毁回调，否则我们定义的销毁方法不执行

         app.registerShutdownHook();

         DependentBean bean = (DependentBean) app.getBean("dependentBean");

         bean.write("\r\n德玛西亚\r\n");

     }

 }

测试完成，控制打印如下：

文件写入：