i encountered HTTP status 500, Please help me! my assignment is going to due soon!!!!!!!!!!! may anyone tell me what's the problem?

org.apache.jasper.JasperException: Could not connect to database.
    at org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:254)
    at org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:295)
    at org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:241)
    at javax.servlet.http.HttpServlet.service(HttpServlet .java:853)
    at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:247)
    at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:256)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.catalina.core.StandardContext.invoke(St andardContext.java:2409)
    at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:180)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.valves.ErrorDispatcherValve.in voke(ErrorDispatcherValve.java:171)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:641)
    at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:172)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:641)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:174)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.coyote.tomcat4.CoyoteAdapter.service(Co yoteAdapter.java:193)
    at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:781)
    at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.processConnection(Http11Protocol.jav a:549)
    at org.apache.tomcat.util.net.TcpWorkerThread.runIt(P oolTcpEndpoint.java:589)
    at org.apache.tomcat.util.threads.ThreadPool$ControlR unnable.run(ThreadPool.java:666)
    at java.lang.Thread.run(Thread.java:536)


root cause

javax.servlet.ServletException: Could not connect to database.
    at org.apache.jasper.runtime.PageContextImpl.handlePa geException(PageContextImpl.java:536)
    at org.apache.jsp.validateLogin_jsp._jspService(valid ateLogin_jsp.java:107)
    at org.apache.jasper.runtime.HttpJspBase.service(Http JspBase.java:137)
    at javax.servlet.http.HttpServlet.service(HttpServlet .java:853)
    at org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:210)
    at org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:295)
    at org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:241)
    at javax.servlet.http.HttpServlet.service(HttpServlet .java:853)
    at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:247)
    at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:256)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.catalina.core.StandardContext.invoke(St andardContext.java:2409)
    at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:180)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.valves.ErrorDispatcherValve.in voke(ErrorDispatcherValve.java:171)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:641)
    at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:172)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:641)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:174)
    at org.apache.catalina.core.StandardPipeline$Standard PipelineValveContext.invokeNext(StandardPipeline.j ava:643)
    at org.apache.catalina.core.StandardPipeline.invoke(S tandardPipeline.java:480)
    at org.apache.catalina.core.ContainerBase.invoke(Cont ainerBase.java:995)
    at org.apache.coyote.tomcat4.CoyoteAdapter.service(Co yoteAdapter.java:193)
    at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:781)
    at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.processConnection(Http11Protocol.jav a:549)
    at org.apache.tomcat.util.net.TcpWorkerThread.runIt(P oolTcpEndpoint.java:589)
    at org.apache.tomcat.util.threads.ThreadPool$ControlR unnable.run(ThreadPool.java:666)
    at java.lang.Thread.run(Thread.java:536)

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++
my Bean file:
import java.sql.*;
import java.util.*;


public class DatabaseBean {

    String error;
    Connection con;

    public DatabaseBean() {}

    public Connection connect() throws ClassNotFoundException,SQLException, Exception
    {
        try
        {
            Class.forName("org.gjt.mm.mysql.Driver").newInstan ce();
            con = DriverManager.getConnection("jdbc:mysql://localhost:1537/pp");
            return con;
        }
        catch (ClassNotFoundException cnfe)
        { error = "Could not locate DB driver.";
            throw new ClassNotFoundException(error);
        }
        catch (SQLException cnfe)
        { error = "Could not connect to database.";
            throw new SQLException(error);
        }
        catch (Exception e)
        { error = "An unknown error occurred while connecting to database.";
            throw new Exception(error);
        }
    }

From the provided piece of source code, you are encountring a SQLException. This type of exception always contain a specific
message about the problem; however, you are masking it by your
generic error message "Could not connect to the database".
Always check the exception getMessage() or getLocalizedMessage()
before providing your own message. If you'll print out the
provided message, you'll find out the exact cause.