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  • #1

    Frage zu doPost()-Methode von Servlets

    Ich habe einen ExtJS-Controller, von welchem aus ich einen AJAX-Request an ein Servlet sende. Die ExtJS-Klasse sieht so aus:

    Code:
    Ext.define('app.view.main.MainController', {
extend: 'Ext.app.ViewController',

alias: 'controller.main',

onItemSelected: function (sender, record) {
Ext.Msg.confirm('Confirm', 'Are you sure?', 'onConfirm', this);
},

onConfirm: function (choice) {
if (choice === 'yes') {

var xhttp = new XMLHttpRequest();
xhttp.open("POST", "/mave/db", true);
xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send("text");

}
}
});

Die doPost-Methode des Servlets wird aufgerufen, das habe ich überprüft. Diese sieht wie folgt aus:

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

processRequest(request, response);


}
    Was ich fragen wollte ist - wie gelange ich in der doPost-Methdode nun an den Text ("text"), welchen ich dem Servlet ja senden will?
    Zuletzt editiert von pkm; 11.09.2019, 09:14.
    Tags: None
  • #2
    https://docs.oracle.com/javaee/6/api...tml#getReader()

    Den Stream in einen String o.a. speichern
    Christian

    Comment

    • #3
      Ich versuche nun den Inhalt des request-Objekts über einen Inputstream auszulesen, einem StringBuilder anzuhängen, um das Ergebnis dann in eine Datei zu speichern, was aber leider auch nicht klappt

      Code:
      /*

* To change this license header, choose License Headers in Project Properties.

* To change this template file, choose Tools | Templates

* and open the template in the editor.

*/

package com.mavenproject.mave;



[JAVA]
import java.io.BufferedWriter;

import java.io.*;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;




/**

*

* @author andfe

*/

public class DB extends HttpServlet {




/**

* Processes requests for both HTTP <code>GET</code> and <code>POST</code>

* methods.

*

* @param request servlet request

* @param response servlet response

* @throws ServletException if a servlet-specific error occurs

* @throws IOException if an I/O error occurs

*/

protected void processRequest(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

try (PrintWriter out = response.getWriter()) {

/* TODO output your page here. You may use following sample code. */

out.println("<!DOCTYPE html>");

out.println("<html>");

out.println("<head>");

out.println("<title>Servlet DB</title>");

out.println("</head>");

out.println("<body>");

out.println("<h1>Servlet DB at " + request.getContextPath() + "</h1>");

out.println("</body>");

out.println("</html>");

}

}




// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">

/**

* Handles the HTTP <code>GET</code> method.

*

* @param request servlet request

* @param response servlet response

* @throws ServletException if a servlet-specific error occurs

* @throws IOException if an I/O error occurs

*/

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

processRequest(request, response);

}




/**

* Handles the HTTP <code>POST</code> method.

*

* @param request servlet request

* @param response servlet response

* @throws ServletException if a servlet-specific error occurs

* @throws IOException if an I/O error occurs

*/

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

processRequest(request, response);

write(request);

}




/**

* Returns a short description of the servlet.

*

* @return a String containing servlet description

*/

@Override

public String getServletInfo() {

return "Short description";

}// </editor-fold>






private void write(HttpServletRequest request) {



BufferedReader reader = null;



String line;

StringBuilder sb = new StringBuilder();

try {



reader = new BufferedReader(new InputStreamReader(request.getInputStream()));



while ((line = reader.readLine()) != null) {

sb.append(line);

}

} catch (IOException e) {

e.printStackTrace();



}finally {




if (reader != null) {

try {

reader.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}



try{



BufferedWriter bw = new BufferedWriter(new FileWriter("C:\\Users\\andfe\\Desktop\\log.txt"));



bw.write(sb.toString());




bw.close();




} catch (IOException e) {

e.printStackTrace();

}

}




}
      Zuletzt editiert von pkm; 11.09.2019, 09:16.

      Comment

      • #4
        Formatiere deinen Beitrag, wer soll sich das so ansehen?
        "was aber leider auch nicht klappt" ist kein Fehler

        https://www.baeldung.com/convert-input-stream-to-string
        Christian

        Comment

        • #5
          Wenn ich den Debugger richtig verstehe, dann werden durch den AJAX-call keine Daten gesendet, denn postData ist Null (siehe Anhang 1). Deswegen bekomme ich auch in der while-Schleife der write()-Methode eine IOException. Ich verstehe nur nicht, was an dem AJAX-call falsch ist.

          Code:
          import java.io.BufferedWriter;
import java.io.*;
import java.io.PrintWriter;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.logging.FileHandler;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.IOUtils;


/**
 *
 * @author andfe
 */
public class DB extends HttpServlet {

    private static final Logger logger = Logger.getLogger(DB.class.getName());

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet DB</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet DB at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
        write(request);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>


    private void write(HttpServletRequest request) {

        setup(logger);
         logger.log(Level.SEVERE, "Logger set up.");

   InputStream inputStream = null;

   try{
       logger.log(Level.SEVERE, "Now reading input stream.");

           try {

               inputStream = request.getInputStream();

           } catch (IOException e) {

            logger.log(Level.SEVERE, "Encountered IOException.");
            e.printStackTrace();

            }


   } catch(NullPointerException e){

       logger.log(Level.SEVERE, "Encountered a NullPointerException.");
       e.printStackTrace();

   }

       if(inputStream == null){

           logger.log(Level.SEVERE, "Inputstream is null.");

       } else{

        logger.log(Level.SEVERE, "Reading result.");

        //String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8); Not like this.
        StringBuilder sb = new StringBuilder();

        byte[] buffer = new byte[1024];
        int length;
        try {
            while ((length = inputStream.read(buffer)) != -1) {
                sb.append(new String(buffer, 0, length));
            }
        } catch (IOException ex) {
            logger.log(Level.SEVERE, "Encountered IOException.");
        }

        if(sb.length() == 0){
          logger.log(Level.SEVERE, "Result empty.");
        }

         logger.log(Level.SEVERE, "Result read.");//But why empty?


    //new PersistEntity().persist(request.getContextPath());
}       
    }

...
          So mache ich den AJAX-call:

          Code:
          Ext.define('app.view.main.MainController', {
    extend: 'Ext.app.ViewController',

    alias: 'controller.main',

    onItemSelected: function (sender, record) {
        Ext.Msg.confirm('Confirm', 'Are you sure?', 'onConfirm', this);
    },

    onConfirm: function (choice) {
        if (choice === 'yes') {  

        var xhttp = new XMLHttpRequest();
        xhttp.open('POST', '/mave/DB', true);
        xhttp.setRequestHeader('Content-type', 'text/html; charset=ISO-8859-1');
        xhttp.send('test');

        }
    }
});
          Attached Files

          Comment

          • #6
            DB ist eine Klasse. Die liegen üblicherweise im WEB-INF Verzeichnis. Das ist für den Clientzugriff gesperrt. Du musst das an eine JSP o.a senden

            Ein Ajax-Aufruf macht doch so keinen Sinn. Es soll doch eine bestehende Seite geändert werden
            Christian

            Comment

            • #7
              Danke für die Tipps. Jetzt funktioniert es wie folgt:

              Code:
              /**
 * This class is the controller for the main view for the application. It is specified as
 * the "controller" of the Main view class.
 *
 * TODO - Replace this content of this view to suite the needs of your application.
 */

Ext.define('app.view.main.MainController', {
    extend: 'Ext.app.ViewController',

    alias: 'controller.main',

    onItemSelected: function (sender, record) {
        Ext.Msg.confirm('Confirm', 'Are you sure?', 'onConfirm', this);
    },

    onConfirm: function (choice) {
        if (choice === 'yes') {  

        var xhttp = new XMLHttpRequest();
        xhttp.open('POST', '/mave/DB', true);
        xhttp.setRequestHeader('Content-type', 'text/plain; charset=ISO-8859-1');
        xhttp.send('dfdsfkjdsfkjsfdsjfsjfdkjl');

        }
    }
});
              Code:
              /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.mavenproject.mave;

import java.io.*;
import java.io.PrintWriter;
import java.util.logging.FileHandler;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author andfe
 */
public class DB extends HttpServlet {

    private static final Logger LOGGER = Logger.getLogger(DB.class.getName());

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet DB</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet DB at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            //doPost(request, response);//Do I need this??
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        write(request);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

    private void write(HttpServletRequest request) {

        LoggerSetup.getInstance().doSetup(LOGGER);
        //setup(LOGGER);

        LOGGER.log(Level.SEVERE, "Logger set up.");

        ServletInputStream inputStream = null;

        try {
            LOGGER.log(Level.SEVERE, "Now reading input stream.");

            try {

                inputStream = request.getInputStream();

            } catch (IOException e) {

                LOGGER.log(Level.SEVERE, "Encountered IOException 1.");

            }

        } catch (NullPointerException e) {

            LOGGER.log(Level.SEVERE, "Encountered a NullPointerException.");

        }

        if (inputStream == null) {

            LOGGER.log(Level.SEVERE, "Inputstream is null.");

        } else {

            LOGGER.log(Level.SEVERE, "Reading result.");

            //String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8); Not like this.
            StringBuilder sb = new StringBuilder();

            byte[] buffer = new byte[1024];
            int length;
            try {                            
                while ((length = inputStream.readLine(buffer, 0, buffer.length)) != -1) {
                    sb.append(new String(buffer, 0, length));
                }
                inputStream.close();

            } catch (IOException ex) {
                LOGGER.log(Level.SEVERE, "Encountered IOException 2.");
            }

            if (sb.length() == 0) {
                LOGGER.log(Level.SEVERE, "Result empty.");
            }

            LOGGER.log(Level.SEVERE, "Result read.");


        }
    }

}

              Comment

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