This program demonstrates how to use the URLConnection class for a POST request.
/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.SwingWorker;
/**
* This program demonstrates how to use the URLConnection class for a POST request.
* @version 1.20 2007-06-25
* @author Cay Horstmann
*/
public class PostTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new PostTestFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}
class PostTestFrame extends JFrame
{
/**
* Makes a POST request and returns the server response.
* @param urlString the URL to post to
* @param nameValuePairs a map of name/value pairs to supply in the request.
* @return the server reply (either from the input stream or the error stream)
*/
public static String doPost(String urlString, Map<String, String> nameValuePairs)
throws IOException
{
URL url = new URL(urlString);
URLConnection connection = url.openConnection();
connection.setDoOutput(true);
PrintWriter out = new PrintWriter(connection.getOutputStream());
boolean first = true;
for (Map.Entry<String, String> pair : nameValuePairs.entrySet())
{
if (first) first = false;
else out.print('&');
String name = pair.getKey();
String value = pair.getValue();
out.print(name);
out.print('=');
out.print(URLEncoder.encode(value, "UTF-8"));
}
out.close();
Scanner in;
StringBuilder response = new StringBuilder();
try
{
in = new Scanner(connection.getInputStream());
}
catch (IOException e)
{
if (!(connection instanceof HttpURLConnection)) throw e;
InputStream err = ((HttpURLConnection) connection).getErrorStream();
if (err == null) throw e;
in = new Scanner(err);
}
while (in.hasNextLine())
{
response.append(in.nextLine());
response.append("\n");
}
in.close();
return response.toString();
}
public PostTestFrame()
{
setTitle("PostTest");
northPanel = new JPanel();
add(northPanel, BorderLayout.NORTH);
northPanel.setLayout(new GridLayout(0, 2));
northPanel.add(new JLabel("Host: ", SwingConstants.TRAILING));
final JTextField hostField = new JTextField();
northPanel.add(hostField);
northPanel.add(new JLabel("Action: ", SwingConstants.TRAILING));
final JTextField actionField = new JTextField();
northPanel.add(actionField);
for (int i = 1; i <= 8; i++)
northPanel.add(new JTextField());
final JTextArea result = new JTextArea(20, 40);
add(new JScrollPane(result));
JPanel southPanel = new JPanel();
add(southPanel, BorderLayout.SOUTH);
JButton addButton = new JButton("More");
southPanel.add(addButton);
addButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
northPanel.add(new JTextField());
northPanel.add(new JTextField());
pack();
}
});
JButton getButton = new JButton("Get");
southPanel.add(getButton);
getButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
result.setText("");
final Map<String, String> post = new HashMap<String, String>();
for (int i = 4; i < northPanel.getComponentCount(); i += 2)
{
String name = ((JTextField) northPanel.getComponent(i)).getText();
if (name.length() > 0)
{
String value = ((JTextField) northPanel.getComponent(i + 1)).getText();
post.put(name, value);
}
}
new SwingWorker<Void, Void>()
{
protected Void doInBackground() throws Exception
{
try
{
String urlString = hostField.getText() + "/" + actionField.getText();
result.setText(doPost(urlString, post));
}
catch (IOException e)
{
result.setText("" + e);
}
return null;
}
}.execute();
}
});
pack();
}
private JPanel northPanel;
}
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