Perhaps JAVA_HOME does not point to the JDK问题（JDK1.6.0+ Tomcat5.0 时出现）

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文章分类:Java编程

错误页面提示：

HTTP Status 500 -

type Exception report

message

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:83)

          org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:315)

          org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:406)

          org.apache.jasper.compiler.Compiler.compile(Compiler.java:463)

          org.apache.jasper.compiler.Compiler.compile(Compiler.java:442)

          org.apache.jasper.compiler.Compiler.compile(Compiler.java:430)

          org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)

          org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:274)

          org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)

          org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)

          javax.servlet.http.HttpServlet.service(HttpServlet.java:810)

Perhaps JAVA_HOME does not point to the JDK问题

Unable to find a javac compiler;Perhaps JAVA_HOME does not point to the JDK异常产生原因和解决方法。
安装tomcat的时候指定了jre的路径，导致tomcat_home, java_home都已经添加到了环境变量里，但启动jsp的时候却出现了以下的异常：
Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK

产生的原因是java.home指到$JAVA_HOME/jre下了，而其lib下的tools.jar跟$JAVA_HOME/lib/tools.jar不一样，编译jsp的时候需要用到后者.

注: java.home在运行的时候就会指向$JRE_HOME.
jdk1.6.0_03

都会出现这种情况.

修改方法：在tomcat控制台(双击tomcate5w.exe)java选项-〉java virtual machine
设置为%java_home%/jre/bin/server/jvm.dll
tomcat控制台java选项-〉Java classpath:
%tomcat_home%/bin/bootstrap.jar;%java_home%/lib/tools.jar
注：%java_home%、%tomcat_home分别指jdk、tomcat的安装根目录

tomcat_home, java_home都已经添加到了环境变量里，但启动jsp的时候却出现了以下的异常
Unable to find a javac compiler; com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK
解决方案：
只要把JAVA_HOME/lib/tools.jar拷到TOMCAT_HOME/common/lib下，重启动Tomcat，OK

以上jdk1.6.0_03 +tomcat5.0.28出现上述现象，并按相应方法解决