ClassNotFoundException: com.sun.el.ExpressionFactoryImpl：错误原因及解决方案

小编在开发springboot+springmvc+hibernate时，访问jsp出现以下错误：（错误原因及解决方案在文章最后）

java.lang.ClassNotFoundException: com.sun.el.ExpressionFactoryImpl
	at org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader.loadClass(TomcatEmbeddedWebappClassLoader.java:68) ~[spring-boot-2.2.0.BUILD-SNAPSHOT.jar:2.2.0.BUILD-SNAPSHOT]
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1188) ~[tomcat-embed-core-9.0.22.jar:9.0.22]
	at javax.el.FactoryFinder.newInstance(FactoryFinder.java:83) ~[el-api-2.2.jar:na]
	at javax.el.FactoryFinder.find(FactoryFinder.java:193) ~[el-api-2.2.jar:na]
......
Caused by: javax.el.ELException: Provider com.sun.el.ExpressionFactoryImpl not found
	at javax.el.FactoryFinder.newInstance(FactoryFinder.java:97) ~[el-api-2.2.jar:na]
	at javax.el.FactoryFinder.find(FactoryFinder.java:193) ~[el-api-2.2.jar:na]
......
Caused by: java.lang.ClassNotFoundException: com.sun.el.ExpressionFactoryImpl
	at org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader.loadClass(TomcatEmbeddedWebappClassLoader.java:68) ~[spring-boot-2.2.0.BUILD-SNAPSHOT.jar:2.2.0.BUILD-SNAPSHOT]
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1188) ~[tomcat-embed-core-9.0.22.jar:9.0.22]
	at javax.el.FactoryFinder.newInstance(FactoryFinder.java:83) ~[el-api-2.2.jar:na]
	... 52 common frames omitted

接下来，看看我的pom.xml

	4.0.0
	
		org.springframework.boot
		spring-boot-starter-parent
		2.2.0.BUILD-SNAPSHOT
		 
	
	
	war
	com.nbc
	springboot_activiti_demo
	0.0.1-SNAPSHOT
	springboot_activiti_demo
	Spring Boot Activiti Demo

	
		1.8
		UTF-8
        5.22.0
        5.22.0 
        1.9.4 
        2.8.2
        0.9.5.2
        2.7.5 
        5.2.0.Final  
        5.2.0.Final
        5.1.0.Final  
        1.0.1.Final 
      
        2.2.0
        4.12  
        1.2
        5.2.0.BUILD-SNAPSHOT
        4.0
        4.0.0
        
	

	
	    
		
			junit
			junit
			${junit.version}
			test
		
		
		
		
			com.google.code.gson
			gson
			${gson.version}
		
		
	    
	    
        
		
			com.microsoft.sqlserver
			sqljdbc4
			${sqlserver.version}
		
		
		
		
		
			com.mchange
			c3p0
			${c3p0.version}
		
		
		
		
			org.springframework
			spring-orm
			${spring.version}
		   
        
		
		
			org.hibernate
			hibernate-core
			${hibernate.core.version}
		
		
			org.hibernate
			hibernate-ehcache
			${hibernate.ehcache.version}
		 
		
			org.hibernate.common
			hibernate-commons-annotations
			${hibernate.annotations.version}
		
		
			org.hibernate.javax.persistence
			hibernate-jpa-2.0-api
			${hibernate.jpa.api.version}
		
		
		
		
			javax.servlet
			javax.servlet-api
			${servlet.api.version}
			provided
		 
		
			javax.servlet
			jstl
			${jstl.version}
		
		 
            org.apache.tomcat.embed
            tomcat-embed-jasper
        
        
            org.apache.tomcat
            tomcat-jsp-api
        
        
		 
		
			org.springframework.boot
			spring-boot-starter
		
		
		   org.springframework.boot
		   spring-boot-starter-web
		
		
			org.springframework.boot
			spring-boot-starter-test
			test
			
				
					org.junit.vintage
					junit-vintage-engine
				
				
					junit
					junit
				
			
		
	

	
	    activiti
		
			
				org.springframework.boot
				spring-boot-maven-plugin
			
			 
		
		
		 
		
	

	
		
			spring-milestones
			Spring Milestones
			https://repo.spring.io/milestone
		
		
			spring-snapshots
			Spring Snapshots
			https://repo.spring.io/snapshot
			
				true
			
		
	
	
		
			spring-milestones
			Spring Milestones
			https://repo.spring.io/milestone
		
		
			spring-snapshots
			Spring Snapshots
			https://repo.spring.io/snapshot
			
				true
			
		
	

以上pom.xml大家看出了什么问题吗？如果没有，那就继续看下文。

报这个错，我就百度了一下错误信息：ClassNotFoundException: com.sun.el.ExpressionFactoryImpl

有的文章说这是jar包冲突，删除el.jar，但我觉得这不可行，springboot的pom.xml都没有配置el.jar却生成war包时lib目录有el.jar，说明el.jar不是用户自己可配置的。因此，jar包冲突的说法就不成立了，搞了两天，一一排除，最后发现，原来是引入Hibernate的jar包不足，所以，请再仔细查看以上pom.xml的Hibernate配置是否有错？我不知道是否有错，因此我就百度了一下Hibernate所需jar包，最后修改Hibernate的配置为以下jar包：

5.1.0.Final
        
        
        
		    org.hibernate
		    hibernate-core
		    ${hibernate.version}
		
		
		
		    org.hibernate
		    hibernate-entitymanager
		    ${hibernate.version}
		 
		
		    org.hibernate
		    hibernate-osgi
		    ${hibernate.version}
		
		
		    org.hibernate
		    hibernate-envers
		    ${hibernate.version}
		
		
		    org.hibernate
		    hibernate-c3p0
		    ${hibernate.version}
		
		
		    org.hibernate
		    hibernate-proxool
		    ${hibernate.version}
		
		
		    org.hibernate
		    hibernate-infinispan
		    ${hibernate.version}
		
		
		    org.hibernate
		    hibernate-ehcache
		    ${hibernate.version}
		 

再启动springboot项目，访问jsp成功。

总结：

springboot错误：Caused by: java.lang.ClassNotFoundException: com.sun.el.ExpressionFactoryImpl

原因之一：Hibernate依赖jar包引入不全（缺少某些Hibernate依赖）

解决方案：添加完整Hibernate依赖。（如上）