java 1.5 和 1.6环境共存的时候发现的错误

Bad version number in .class file
由这个看是版本问题！！但是又不知道具体信息

java.lang.UnsupportedClassVersionError: Bad version number in .class file
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at sun.applet.AppletClassLoader.loadClass(AppletClassLoader.java:119)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at sun.applet.AppletClassLoader.loadCode(AppletClassLoader.java:591)
at sun.applet.AppletPanel.createApplet(AppletPanel.java:712)
at sun.applet.AppletPanel.runLoader(AppletPanel.java:641)
at sun.applet.AppletPanel.run(AppletPanel.java:320)
at java.lang.Thread.run(Thread.java:595)

这两天是这个错误：

org.apache.jasper.JasperException: Bad version number in .class file

root cause

java.lang.UnsupportedClassVersionError: Bad version number in .class file
        java.lang.ClassLoader.defineClass1(Native Method)
        java.lang.ClassLoader.defineClass(Unknown Source)
        java.security.SecureClassLoader.defineClass(Unknown Source)
        org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1815)
        org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:869)
        org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1322)
        org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1201)
        org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:127)
        org.apache.jasper.servlet.JasperLoader.loadClass(JasperLoader.java:65)
        java.lang.ClassLoader.loadClassInternal(Unknown Source)
        org.apache.jsp.index_jsp._jspService(index_jsp.java:57)
        org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:334)
        org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
        org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

baidu,google上说是因为编译和运行的版本不一样，可是并没有啊，如附图，

无意间在百度上搜了一个关键字，大致提了一下这个东东，于是照着看了一下我的IDE（JBoss-IDE2.0.0）里面的Java-Compiler选项，发现Compiler Compliance level 居然默认的是6.0的JDK，而我装的是5.0的JDK。改成5.0，重新Deploye一下，这个问题总算是没有了，如附图：

但是又发生如下错误，看不懂：

java.lang.ClassCastException: $Proxy96
org.apache.jsp.index_jsp._jspService(index_jsp.java:63)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:334)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:314)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:264)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)