Unsupported major.minor version 51.0详解编程语言

1、问题

运行 spring boot 时报以下错误信息

  .   ____          _            __ _ _ 
 /// / ___'_ __ _ _(_)_ __  __ _ / / / / 
( ( )/___ | '_ | '_| | '_ // _` | / / / / 
 ///  ___)| |_)| | | | | || (_| |  ) ) ) ) 
     |____| .__|_| |_|_| |_/__, | / / / / 
 =========|_|==============|___/=/_/_/_/ 
 :: Spring Boot ::        (v1.2.2.RELEASE) 
 
 
java.lang.UnsupportedClassVersionError: javax/annotation/ManagedBean : Unsupported major.minor version 51.0

检查Java版本 使用的是1.6

java version "1.6.0_43" 
Java(TM) SE Runtime Environment (build 1.6.0_43-b01) 
Java HotSpot(TM) 64-Bit Server VM (build 20.14-b01, mixed mode)

2、原因

报错的为 javax/annotation/ManagedBean 找到这个类所在jar

打开里面的MANIFEST.MF文件

Manifest-Version: 1.0 
Ant-Version: Apache Ant 1.9.3 
Created-By: 1.7.0_67-b01 (Oracle Corporation) 
Specification-Title: Apache Tomcat 
Specification-Version: 8.0 
Specification-Vendor: Apache Software Foundation 
Implementation-Title: Apache Tomcat 
Implementation-Version: 8.0.20 
Implementation-Vendor: Apache Software Foundation 
X-Compile-Source-JDK: 1.7 
X-Compile-Target-JDK: 1.7

可以看出需要 jdk1.7的编译

参考JDK各版本对应的错误编码：

J2SE 8 = 52  
J2SE 7 = 51  
J2SE 6.0 = 50  
J2SE 5.0 = 49  
JDK 1.4 = 48  
JDK 1.3 = 47  
JDK 1.2 = 46  
JDK 1.1 = 45 

3、解决

下载JDK7，将 1.6 换成 1.7 即可

作者：blog.ytso.com