Servlet doesn't write to mySQL DB, why???

Question

I made a servlet that should write a string to a MySQL DB but it doesn't. I have coded the entire DB writing process before the servlet and it worked OUTSIDE a servlet, I mean, it writed to the DB when it was ran in a JAVA API apart from servlet. Now, the servlet is not writing it, please check my code to tell me what's wrong, thanks
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.BufferedReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.FactoryConfigurationError;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.w3c.dom.*;
import org.apache.xml.serialize.*;
import java.net.URLDecoder;
import java.sql.*;
import org.xml.sax.InputSource;
import java.io.StringReader;
* This class is made as a servlet for receiving strings and saving
* them as DB records and XML files, it will save each sms in a different XML
* generating the automatic number of the SMS.
* <p>Bugs: (None untill now, please notify if you find one)
* @author (Helder Martins ([email protected]))
public class xmlwriter extends HttpServlet
//Public variables we will need
public String Stringid;
public String Stringpath;
public String st;
public int nid;
//Servlet service method, which permits listening of events
public void service(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
try {
//Initialization for reading XMLs
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse (new File("C:/Program Files/Apache Software Foundation/Tomcat 5.0/webapps/XMLSender/conf.xml"));
//XML reading....
NodeList listaconf = doc.getElementsByTagName("conf");
for(int s=0; s<listaconf.getLength() ; s++)
Node nodosms = listaconf.item(s);
if(nodosms.getNodeType() == Node.ELEMENT_NODE)
Element elementoconf = (Element)nodosms;
//-------First Node (ID)
NodeList listaid = elementoconf.getElementsByTagName("id");
Element elementoid = (Element)listaid.item(0);
NodeList textidList = elementoid.getChildNodes();
Stringid = ((Node)textidList.item(0)).getNodeValue().trim();
//Incrementing the ID into the XML
st=Stringid;
nid = Integer.parseInt(st);
nid = nid + 1;
st = Integer.toString(nid);
((Node)textidList.item(0)).setNodeValue(st);
//Writing the changes to the XML...
OutputFormat format = new OutputFormat(doc);
FileWriter fw = new FileWriter("C:/Program Files/Apache Software Foundation/Tomcat 5.0/webapps/XMLSender/conf.xml");
XMLSerializer serial = new XMLSerializer(fw, format);
serial.asDOMSerializer();
serial.serialize(doc.getDocumentElement());
fw.close();
//System.out.println(Stringid);
//-------Second Node (Path for the messages)
NodeList listapath = elementoconf.getElementsByTagName("path");
Element elementopath = (Element)listapath.item(0);
NodeList textpathList = elementopath.getChildNodes();
Stringpath = ((Node)textpathList.item(0)).getNodeValue().trim();
//System.out.println(Stringpath);
//Catching errors for the SAX and XML parsing
catch (SAXParseException err)
System.out.println ("** Parsing error" + ", line " + err.getLineNumber () + ", uri " + err.getSystemId ());
System.out.println(" " + err.getMessage ());
catch (SAXException e)
Exception x = e.getException ();
((x == null) ? e : x).printStackTrace ();
catch (Throwable t)
t.printStackTrace ();
//Initialization for the servlet
ServletOutputStream salida = res.getOutputStream();
ServletInputStream entrada = req.getInputStream();
//Reading of the entering string
BufferedReader lector = new BufferedReader(new InputStreamReader (entrada));
res.setContentType("text/HTML");
try {
//Database handler
Class.forName("org.gjt.mm.mysql.Driver");
DocumentBuilderFactory factory =
DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
InputSource inStream = new InputSource();
inStream.setCharacterStream(new StringReader(lector.readLine()));
Document doc1 = builder.parse(inStream);
NodeList listasms = doc1.getElementsByTagName("sms");
for(int s=0; s<listasms.getLength() ; s++)
Connection Conn = DriverManager.getConnection ("jdbc:mysql://localhost:3306/smsdb","root", "");
Node nodosms = listasms.item(s);
if(nodosms.getNodeType() == Node.ELEMENT_NODE){
Element elementosms = (Element)nodosms;
NodeList listatelf = elementosms.getElementsByTagName("tlf");
Element elementotelf = (Element)listatelf.item(0);
NodeList textTelfList = elementotelf.getChildNodes();
String telefono = ((Node)textTelfList.item(0)).getNodeValue();
//String SendingAddress = ((Node)textAddressList.item(0)).getNodeValue().trim();
//System.out.println(telefono);
NodeList listaop = elementosms.getElementsByTagName("op");
Element elementoop = (Element)listaop.item(0);
NodeList textOpList = elementoop.getChildNodes();
String operadora = ((Node)textOpList.item(0)).getNodeValue();
NodeList listasc = elementosms.getElementsByTagName("sc");
Element elementosc = (Element)listasc.item(0);
NodeList textSCList = elementosc.getChildNodes();
String shortcode = ((Node)textSCList.item(0)).getNodeValue();
NodeList listabody = elementosms.getElementsByTagName("body");
Element elementobody = (Element)listabody.item(0);
NodeList textBodyList = elementobody.getChildNodes();
String body = ((Node)textBodyList.item(0)).getNodeValue();
Statement st = Conn.createStatement();
st.executeUpdate("INSERT INTO smstable (telf,op,sc,body) VALUES ('" + telefono + "','" + operadora + "','" + shortcode + "','" + body + "')");
Conn.commit();
Conn.close(); }
//Writing the SMS string to an XML file
String path;
path = Stringpath + "sms" + "0" + st + ".xml";
File f1 = new File (path);
FileWriter out1 = new FileWriter(f1);
PrintWriter wr = new PrintWriter(out1);
f1.createNewFile();
String inputLine;
//Reading the communication
while ((inputLine = lector.readLine()) != null)
wr.write(URLDecoder.decode(inputLine, "UTF-8"));
lector.close();
out1.close();
salida.println(path);
salida.println(inputLine);
//Catching errors for the SAX and XML parsing
catch (SAXParseException err)
System.out.println ("** Parsing error" + ", line " + err.getLineNumber () + ", uri " + err.getSystemId ());
System.out.println(" " + err.getMessage ());
catch (SAXException e)
Exception x = e.getException ();
((x == null) ? e : x).printStackTrace ();
catch (Throwable t)
t.printStackTrace ();

Answer 1

Do you get any exceptions? Any messages in the logs to tell you why this happens?
Personally, I think you should not catch a Throwable. Unchecked exceptions shouldn't be caught.
It's a good idea to code all your database logic into a separate object so you can test it off-line. If you did that, as you say, why did you cut & paste the code back into your servlet? Why not leave it inside another Java Bean that your servlet simply instantiates and invokes?
Your method is too big. You'd be better off decomposing this problem into more objects that are more discrete and cohesive.
Can't tell what went wrong based on the little you've posted. I'd be surprised if anyone had time to review this code. I know I don't. Be more specific about what's wrong and you'll have better luck.