1.JSP无法编译

错误提示：

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

org.apache.jasper.JasperException: Unable to compile class for JSP

No Java compiler was found to compile the generated source for the JSP. 
This can usually be solved by copying manually $JAVA_HOME/lib/tools.jar from the JDK 
to the common/lib directory of the Tomcat server, followed by a Tomcat restart. 
If using an alternate Java compiler, please check its installation and access path.

org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:128)
 org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:351)
 org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:413)
 org.apache.jasper.compiler.Compiler.compile(Compiler.java:453)
 org.apache.jasper.compiler.Compiler.compile(Compiler.java:437)
 org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:555)
 org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:291)
 org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
 org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:856)

note The full stack trace of the root cause is available in the Tomcat logs.

解决办法

法一：把jdk安装目录下lib/tools.jar 复制到tomcat  的common/lib 下就ok了
法二：修改jvm大小
JAVA_OPTS="-server -Xms512m -Xmx1024m"