jar包和classes的区别？？（jar包可用，class不可用）
有个jar包在WEB-INF\lib下，运行正常，
我把jar包的class文件释放到WEB-INF\classes，并把这个jar包删除，就报如下错误，数据不能正常显示
不知道是那里错误。
路径和文件都是正确的
StandardWrapperValve[jsp]:   Servlet.service()   for   servlet   jsp   threw   exception
java.lang.NoClassDefFoundError:   com/isomorphic/sql/SQLDriver
                at   org.apache.jsp.examples.server_005fintegration.custom_005fdatasource_
005foperations.supplyItemOperations_jsp._jspService(supplyItemOperations_jsp.jav
a:113)
                at   org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
                at   javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
                at   org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:324)
                at   org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:2
92)
                at   org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
                at   javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
                at   org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:237)
                at   org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:157)
                at   com.isomorphic.js.JSSyntaxScannerFilter.doFilter(JSSyntaxScannerFilte
r.java:251)
                at   org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:186)
                at   org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:157)
                at   com.isomorphic.servlet.CompressionFilter.doFilter(CompressionFilter.j
ava:248)
                at   org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:186)
                at   org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:157)
                at   org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:214)
                at   org.apache.catalina.core.StandardValveContext.invokeNext(StandardValv
eContext.java:104)
                at   org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:520)
                at   org.apache.catalina.core.StandardContextValve.invokeInternal(Standard
ContextValve.java:198)
                at   org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:152)
              &nbs