狗血一样的剧情，丢人事迹写成博客，检讨自己，提示后人。

剧情是这样：

公司有一套自己的parent POM，用以统一各系统的依赖，所以就不方便采用Spring Boot的继承方式了，也就是如下的方式：

    
    	
     
      4.0.0
     	
     		
      
       org.springframework.boot
      		
      
       spring-boot-dependencies
      		
      
       1.3.8.RELEASE
      	
     	
     
      com.aaa.bbb
     	
     
      aaa-bbb
     	
     
      jar
     	
     
      1.0.0-SNAPSHOT
     	
     
      aaa-bbb
     	
     		
      			
       
        org.springframework.boot
       			
       
        spring-boot-starter-web
       		
      	
     
    

根据实际项目需要，得将POM文件改为如下依赖的写法：

    
    	
     
      4.0.0
     	
     		
      
       aaa-bbb
      		
      
       aaa-bbb-parent
      		
      
       2.0-SNAPSHOT
      	
     	
     
      com.aaa.bbb
     	
     
      aaa-bbb
     	
     
      jar
     	
     
      1.0.0-SNAPSHOT
     	
     
      aaa-bbb
     	
     		
      			
       				
        				
        
         org.springframework.boot
        				
        
         spring-boot-dependencies
        				
        
         1.3.8.RELEASE
        				
        
         pom
        				
        
         import
        			
       		
      	
     	
     		
      			
       
        org.springframework.boot
       			
       
        spring-boot-starter-web
       		
      	
     
    

为了方便解释问题，也把这个DEMO中唯一的Java类贴出来（Java类中没错误）：

package com.aaa.bbb;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.EnableAutoConfiguration;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;@Controller@EnableAutoConfigurationpublic class SampleController {	@RequestMapping("/")	@ResponseBody	String home() {		return "Hello World!";	}	public static void main(String[] args) throws Exception {		SpringApplication.run(SampleController.class, args);	}}

但是实际写的过程中，一直出现如下的这个错误：

Exception in thread "main" java.lang.IllegalArgumentException: Cannot instantiate interface org.springframework.context.ApplicationListener : org.springframework.boot.logging.ClasspathLoggingApplicationListener	at org.springframework.boot.SpringApplication.createSpringFactoriesInstances(SpringApplication.java:413)	at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:393)	at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:384)	at org.springframework.boot.SpringApplication.initialize(SpringApplication.java:262)	at org.springframework.boot.SpringApplication.
    
     (SpringApplication.java:236)	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1185)	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1174)	at com.turing.log2.SampleController.main(SampleController.java:20)Caused by: java.lang.NoClassDefFoundError: org/springframework/context/event/GenericApplicationListener	at java.lang.ClassLoader.defineClass1(Native Method)	at java.lang.ClassLoader.defineClass(Unknown Source)	at java.security.SecureClassLoader.defineClass(Unknown Source)	at java.net.URLClassLoader.defineClass(Unknown Source)	at java.net.URLClassLoader.access$100(Unknown Source)	at java.net.URLClassLoader$1.run(Unknown Source)	at java.net.URLClassLoader$1.run(Unknown Source)	at java.security.AccessController.doPrivileged(Native Method)	at java.net.URLClassLoader.findClass(Unknown Source)	at java.lang.ClassLoader.loadClass(Unknown Source)	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)	at java.lang.ClassLoader.loadClass(Unknown Source)	at org.springframework.util.ClassUtils.forName(ClassUtils.java:249)	at org.springframework.boot.SpringApplication.createSpringFactoriesInstances(SpringApplication.java:406)	... 7 moreCaused by: java.lang.ClassNotFoundException: org.springframework.context.event.GenericApplicationListener	at java.net.URLClassLoader.findClass(Unknown Source)	at java.lang.ClassLoader.loadClass(Unknown Source)	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)	at java.lang.ClassLoader.loadClass(Unknown Source)	... 21 more
    

查了半天，才突然意识到问题，于是我对比了一下spring-boot的对spring依赖的版本号：

Spring Boot 1.3.8.RELEASE 对应是 Spring 4.2.8.RELEASE，

而我公司的parent中，spring版本统一为4.1.7.RELEASE。

和JDK版本，DEMO搭建等等均没关系，这些时间花费的太冤枉了……小黑屋见……