jsp调用javabean

调用：
<HTML>
<HEAD>
    <TITLE></TITLE>
</HEAD>
<BODY>
<%
import java.sql.*;ResultSet Rs = null;%>
<jsp:useBean id="DbBean" beanName="DbOper" class="DbOper" scope="page"></jsp:useBean>
<%
  Rs = DbOper.DbQuery( "select * from customer" );
  int iCount = Rs.getRow();
  if( iCount>0 )
  {
%>
<center><%=iCount%></center>
<%
  }
%>
</BODY>
</HTML>

解决方案 »

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http://localhost:8080/jsp_test.jspHTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: /jsp_test.jsp(11,0) jsp.error.useBean.notBoth
at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:94)
at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:428)
at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:140)
at org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:406)
at org.apache.jasper.compiler.Node$UseBean.accept(Node.java:592)
at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:1028)
at org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:1070)
at org.apache.jasper.compiler.Node$Visitor.visit(Node.java:1076)
at org.apache.jasper.compiler.Node$Root.accept(Node.java:232)
at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:1028)
at org.apache.jasper.compiler.Validator.validate(Validator.java:607)
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:230)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:369)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:473)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:190)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:594)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
at java.lang.Thread.run(Thread.java:484)--------------------------------------------------------------------------------Apache Tomcat/4.1.24
我直接在页面这样写代码是成功的
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<%@ page language="java" import="java.sql.*" %>
<html>
<head>
<title>Untitled</title>
</head>
<body>
<%
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
Connection cnn = DriverManager.getConnection("jdbc:odbc:BorlandDemosDb","admin","");
Statement  stmt=cnn.createStatement();
ResultSet rs = stmt.executeQuery( "select * from customer" );
// rs.last();
// out.println( rs.getRow() );
while( rs.next() )
{
out.println( rs.getString("CustNo") );
}
%>
</body>
</html>
<jsp:useBean id="DbBean" beanName="DbOper" class="DbOper" scope="page"></jsp:useBean>
这行有错误,改为
<jsp:useBean id="DbBean" beanName="DbOper" class="java_test.DbOpen" scope="page"></jsp:useBean>包路径必须要写完整
package java_test;import java.sql.*;你把package java_test去掉试试看看package 是建立包的可是你调用的时候却没有调用包
龙威讲的很对。
另外，你在tomcat/webapps/root/web-inf/classes下建一个文件夹java_test,将你的Dboper.class文件放进去.
我的jsp：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<%@ page language="java" import="java.sql.*"%>
<html>
<head>
<title>Untitled</title>
</head>
<body>
<jsp:useBean id="BeanId" class="test.DbBean" scope="page"></jsp:useBean>
<%
ResultSet rs = BeanId.dbQuery( "select * from customer" );
if( rs == null )//用这条语句检测表明 rs=null,难怪不出错。javabean中不能返回记录集？
{
  out.println( "rs is null" );
}
// out.println( rs.getRow() );
// while( rs.next() )
{
// out.println( rs.getString("CustNo") );
}
%>
</body>
</html>
我的javabean:
package test;import java.sql.*;public class DbBean{
  private String Hello = "only a test";
  private static ResultSet rs = null;

  public String getHello()
  {
    return Hello;
  }
  public void setHello(String newValue)
  {
    Hello = newValue;
  }
  public ResultSet dbQuery(String Sql)
  {
    try
    {
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
      Connection cnn = DriverManager.getConnection("jdbc:odbc:BorlandDemosDb","admin","");
      Statement stmt = cnn.createStatement(java.sql.ResultSet.TYPE_SCROLL_INSENSITIVE,java.sql.ResultSet.CONCUR_READ_ONLY);
      rs = stmt.executeQuery( Sql );
      return rs;
//      return stmt.executeQuery( Sql );
//      PreparedStatement stmt = cnn.prepareStatement(Sql);
//      ResultSet rs = stmt.executeQuery();
//      return rs;
    }
    catch( Exception e)
    {
      return null;
    }
  }
}