I am having difficulty with getting this work. I can connect to the database without problem, however I can not make it show me the html page. It does not run.
import java.io.*;
import java.sql.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ShowBedrock extends HttpServlet
{
public String getServletInfo()
{
return "Servlet connects to PostgreSQL database and displays result of a SELECT";
}
private Connection dbcon; // Connection for scope of ShowBedrock
// "init" sets up a database connection
public void init(ServletConfig config) throws ServletException
{
String loginUser = "postgres";
String loginPasswd = "supersecret";
String loginUrl = "jdbc:postgresql://localhost/bedrock";
// Load the PostgreSQL driver
try
{
Class.forName("org.postgresql.Driver");
dbcon = DriverManager.getConnection(loginUrl, loginUser, loginPasswd);
}
catch (ClassNotFoundException ex)
{
System.err.println("ClassNotFoundException: " + ex.getMessage());
throw new ServletException("Class not found Error");
}
catch (SQLException ex)
{
System.err.println("SQLException: " + ex.getMessage());
}
}
// Use http GET
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html"); // Response mime type
// Output stream to STDOUT
PrintWriter out = response.getWriter();
out.println("<HTML><Head><Title>Bedrock</Title></Head>");
out.println("<Body><H1>Bedrock</H1>");
try
{
// Declare our statement
Statement statement = dbcon.createStatement();
String query = "SELECT name, dept, ";
query += " jobtitle ";
query += "FROM employee ";
// Perform the query
ResultSet rs = statement.executeQuery(query);
out.println("<table border>");
// Iterate through each row of rs
while (rs.next())
{
String m_name = rs.getString("name");
String m_dept = rs.getString("dept");
String m_jobtitle = rs.getString("jobtitle");
out.println("<tr>" +
"<td>" + m_name + "</td>" +
"<td>" + m_dept + "</td>" +
"<td>" + m_jobtitle + "</td>" +
"</tr>");
}
out.println("</table></body></html>");
statement.close();
}
catch(Exception ex)
{
out.println("<HTML>" +
"<Head><Title>" +
"Bedrock: Error" +
"</Title></Head>\n<Body>" +
"<P>SQL error in doGet: " +
ex.getMessage() + "</P></Body></HTML>");
return;
}
out.close();
}
}
I get the following error any body knows why?:
javax.servlet.ServletException: Class not found Error
ShowBedrock.init(ShowBedrock.java:42)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Unknown Source)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.
I get the following error any body knows why?
The reason why you are getting that error body is that your handler for ClassNotFoundException is throwing away the original exception stacktrace. You are writing the original exception's message to System.err but (obviously) that won't go into the normal system logs. (You'll probably find find the message in the "catalina.out" file ... depending on how Tomcat is configured / launched.)
The right way to do this is to either chain the exception; e.g.
throw new ServletException("Class not found Error", e);
or log it explicitly at the point that you catch it. And if you do log it explicitly, make sure that you log the exception, and not just the exception message.
We can't tell you the actual root cause of the problem unless we see the original exception stacktrace ... but the two most likely causes are: