Servlet代码中的java.lang.ClassNotFoundException错误

Question

执行上面的代码后，我遇到了java.lang.ClassNotFoundException错误。如果有人能查看这段代码，我会很高兴的。我正在使用oracle 11g数据库，并且所有数据库连接详细信息都是正确的。在执行代码时也有HTTP状态500 - 内部服务器错误。

 import java.io.*;  
    import java.sql.*;  
    import javax.servlet.ServletException;  
    import javax.servlet.http.*; 



     public class Search extends HttpServlet {  

    public void doGet(HttpServletRequest request, HttpServletResponse response)  
                throws ServletException, IOException {  



        response.setContentType("text/html");  
    PrintWriter out = response.getWriter();  

    String rollno=request.getParameter("roll");  
    int roll=Integer.valueOf(rollno);

        try{  
    Class.forName("oracle.jdbc.driver.OracleDriver");  
    Connection con=DriverManager.getConnection(  
    "jdbc:oracle:thin:@localhost:1521:xe","system","oracle");  

    PreparedStatement ps=con.prepareStatement("select * from result where rollno=?");  
    ps.setInt(1,roll);  

    out.print("<table width=50% border=1>");  
    out.print("<caption>Result:</caption>");  



     ResultSet rs=ps.executeQuery();  

    /* Printing column names */  
    ResultSetMetaData rsmd=rs.getMetaData();  
    int total=rsmd.getColumnCount();  
    out.print("<tr>");  
    for(int i=1;i<=total;i++)  
    {  
    out.print("<th>"+rsmd.getColumnName(i)+"</th>");  
    }  



     out.print("</tr>");

        out.print("</tr>");  

    /* Printing result */  

    while(rs.next())  
    {  
    out.print("<tr><td>"+rs.getInt(1)+"</td><td>"+rs.getString(2)+"  
    </td><td>"+rs.getString(3)+"</td><td>"+rs.getString(4)+"</td></tr>");  

    }  


        out.print("</table>");  

    }catch (Exception e2) {e2.printStackTrace();}  

    finally{out.close();}  

    }  
    }  

   I'm using oracle 11g database and all database connection details are correct. 

我正在使用oracle 11g数据库，并且所有数据库连接详细信息都是正确的。