# Servlet request.getParameter() allways returns null



## 1993maik1993 (14. Dezember 2010)

Huhu leute,

ich habe ein servlet geschrieben welches daten aus der datenbank ausliest und sie dann in einer tabelle ausgibt, problem ist: 
	
	
	



```
request.getParameter()
```
 ist immer null...

```
package de.XXX.restaurante;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Kundenbewertungen extends HttpServlet {

	private String sitepart1, sitepart2 ="", sitepart3, sitepart0, name, meal, mark, comment, data;
	private PrintWriter out;
	private Connection dbConnection;
	private Statement statement;
	private ResultSet res;
	
		public void doPost(HttpServletRequest request, HttpServletResponse response)
				throws IOException, ServletException {
			response.setContentType("text/html");
			out = response.getWriter();
			name = request.getParameter("name");
			meal = request.getParameter("meal");
			System.out.println(request.getParameter("name") + "|_-_-_|" + request.getParameter("meal"));
			mark = request.getParameter("mark");
			comment = request.getParameter("iscommentthere");
			System.out.println(request.getParameter("mark") + "|_-_-_|" + request.getParameter("iscommentthere"));
			addTableEntryToDB();
			makePage();
		}

	public void addTableEntryToDB() {
		try {
			data = "INSERT INTO tableentries(name, meal, mark, comment)"
					+ "VALUES ('" + name + "','" + meal + "','" + mark + "',"
					+ "'" + comment + "')";
			Class.forName("com.mysql.jdbc.Driver").newInstance();
			dbConnection = DriverManager
					.getConnection("jdbc:mysql://127.0.0.1:3306/webprojects?user=root&password=123456");
			statement = dbConnection.createStatement();
			if ((name != null) && (meal != null) && (mark != null) && (comment != null)) {
				statement.executeUpdate(data);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (InstantiationException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		}
	}

	public void makePage() {
			sitepart1 = "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" " +
					"\"http://www.w3.org/TR/html4/loose.dtd\"><html><head><meta http-equiv" +
					"=\"Content-Type\" content=\"text/html; charset=ISO-8859-1\"><title>Ku" +
					"ndenbewertungen unseres Restaurante</title><link type=\"text/css\" re" +
					"l=\"stylesheet\" href=\"style.css\" /></head><body><h2>Bewertungen</h" +
					"2><p>Auf dieser Seite können Sie Bewertungen anderer Gäste einsehen o" +
					"der selbst unser Essen bewerten.<br />Außerdem können Sie ein Komment" +
					"ar zu Ihrer Bewertung abgeben oder vorhandene Kommentare anderer Gäst" +
					"e lesen.</p><table><thead class=\"bewertung\"><tr><td width=\"35%\">K" +
					"undenname</td><td width=\"35%\">Gericht</td><td width=\"15%\">Bewertu" +
					"ng</td><td width=\"15%\">Kommentar vorhanden</td></tr></thead>";
				
			try {
				data = "SELECT * FROM tableentries";
				res = statement.executeQuery(data);
				res.next();
				for (int i = 0; i < res.getRow(); i++) {
					if(i % 2 == 1) {
						sitepart2 = sitepart2 + "<tr id=\"highligthed\"><td>" + res.getString(1) +
						"</td><td>" + res.getString(2) + "</td><td>" + res.getString(3) +
						"</td><td>" + res.getString(4) + "</td></tr>";
					} else if (i % 2 == 0) {
						sitepart2 = sitepart2 + "<tr><td>" + res.getString(1) +
						"</td><td>" + res.getString(2) + "</td><td>" + res.getString(3) +
						"</td><td>" + res.getString(4) + "</td></tr>";
					}
					res.next();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}
				
			sitepart3 = "<tr><td><input type=\"text\" name=\"name\" class=\"withborder\" id" +
					"=\"input1\" /></td><td><input type=\"text\" name=\"meal\" class=\"with" +
					"border\" id=\"input2\" /></td><td><select name=\"mark\" id=\"select1\"" +
					"><option value=\"1\">1</option><option value=\"2\">2</option><option v" +
					"alue=\"3\">3</option><option value=\"4\">4</option><option value=\"5\"" +
					">5</option><option value=\"6\">6</option></select></td><td><select nam" +
					"e=\"iscommentthere\" id=\"select2\"><option value=\"Ja\">Ja</option><o" +
					"ption value=\"Nein\">Nein</option></select></td></tr></table><br /><br" +
					" />Kommentar:<br /><textarea name=\"comment\" rows=\"5\" cols=\"40\"><" +
					"/textArea><br /><br /><form method=\"POST\" action=\"Bewertung.html\">" +
					"<input type=\"submit\" name=\"submitmark\" value=\"Bewertung abgeben\"" +
					" /></form><center><p class=\"links\"><a href=\"Impressum.html\">Impres" +
					"sum</a>    <a href=\"Index.html\">Zurück zum Start</a></p></center></b" +
					"ody></html>";
			
			sitepart0 = sitepart1 + sitepart2 + sitepart3;
			out.println(sitepart0);
			sitepart0 = "";
			sitepart1 = "";
			sitepart2 = "";
			sitepart3 = "";
		}
		
	}
```


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## z-mon (19. Dezember 2010)

Wie sieht denn der Aufruf des Servlets aus?
Hast du in dem Formular auch die "POST" Methode angegeben?
Sind alle Parameter null?

Als kleine Hilfe kann ich dir das Servlets und Java Server Pages (JSP) Tutorial empfehlen.

Grüße


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