jsp里如何调用javabean！关于tomcat设置和文件放置问题！！！

Question

还要配置WEB应用程序的路径...

Answer 1

以下是页面错误提示：
》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: Unable to compile class for JSPAn error occurred at line: 6 in the jsp file: /usebean.jspGenerated servlet error:
    [javac] Compiling 1 source fileC:\Tomcat 4.1\work\Standalone\localhost\_\usebean_jsp.java:47: package first does not exist
      first.helloworld helloBean = null;
           ^An error occurred at line: 6 in the jsp file: /usebean.jspGenerated servlet error:
C:\Tomcat 4.1\work\Standalone\localhost\_\usebean_jsp.java:49: package first does not exist
        helloBean = (first.helloworld) pageContext.getAttribute("helloBean", PageContext.PAGE_SCOPE);
                          ^An error occurred at line: 6 in the jsp file: /usebean.jspGenerated servlet error:
C:\Tomcat 4.1\work\Standalone\localhost\_\usebean_jsp.java:52: package first does not exist
            helloBean = (first.helloworld) java.beans.Beans.instantiate(this.getClass().getClassLoader(), "first.helloworld");
                              ^
3 errors
at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:85)
at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:248)
at org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:315)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:328)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:427)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:142)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:240)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:187)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:200)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:146)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:209)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:144)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2358)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:133)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:118)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:594)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:116)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:594)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:127)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:152)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Unknown Source)--------------------------------------------------------------------------------Apache Tomcat/4.1.31
》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》》
请帮忙下，，谢谢

Answer 2

helloworld.java源码：
package first;
import java.io.*;
public class helloworld
{
 public  String name="First";
 public String getHi()
 {
  return "hello from"+name;
}
}usebean.jsp源码：
<html>
<head>
<title>welcome!!!</title>
</head><body>
<jsp:useBean id="helloBean" scope="page" class="first.helloworld"/>
<%=helloBean.getHi() %><hr>
<% 
helloBean.name="Second";
out.print(helloBean.getHi()); %></body>
</html>

Answer 3

有可能你把web.xml或server.xml 改乱了

Answer 4

http://localhost:8080/usebean.jsp 能够访问，看来你是把 usebean.jsp 放在 ROOT 下，把你的 helloworld.java 放在 ROOT/WEB-INF/classes 下，并到该目录下执行 javac -d . helloworld.java 就可以了。

Answer 5

D:\jakarta-tomcat-5.0.12\work\Catalina\localhost\_\org\apache\jsp\library\login_jsp.java:42: cannot access news.connAn error occurred at line: 2 in the jsp file: /library/login.jspGenerated servlet error:
bad class file: D:\jakarta-tomcat-5.0.12\webapps\ROOT\WEB-INF\classes\news\conn.class
class file contains wrong class: conn.conn
Please remove or make sure it appears in the correct subdirectory of the classpath.
      news.conn conn = null;
          ^

Answer 6

把你的 conn.java 贴出来看看吧。