在java web开发的过程中，有时在资料上可能会提到环境所要支持的JSP，Servlet版本。如果版本低就可能出现测试错误。
方法：打开tomcat的commonlib 目录下，有两个JAR文件： jsp-api.jar servlet-api.jar 。如果没有，那可能是你没有添加进来。解压这两个文件，用记事本分别打开META-INF下的MAINMEFT.MF文件。
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.9
Created-By: 1.8.0_131-b11 (Oracle Corporation)
X-Compile-Source-JDK: 1.8
X-Compile-Target-JDK: 1.8
Name: javax/servlet/jsp/
Specification-Title: Java API for JavaServer Pages
Specification-Version: 2.3
Specification-Vendor: Sun Microsystems, Inc.
Implementation-Title: javax.servlet.jsp
Implementation-Version: 2.3.FR
Implementation-Vendor: Apache Software Foundation
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.9.9
Created-By: 1.8.0_131-b11 (Oracle Corporation)
X-Compile-Source-JDK: 1.8
X-Compile-Target-JDK: 1.8
Name: javax/servlet/
Specification-Title: Java API for Servlets
Specification-Version: 4.0
Specification-Vendor: Sun Microsystems, Inc.
Implementation-Title: javax.servlet
Implementation-Version: 4.0.EDR-b01
Implementation-Vendor: Apache Software Foundation