URLConnectionTest.java Source code

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Here is the source code for URLConnectionTest.java

Source

/*
   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.io.ByteArrayOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

/**
 * This program connects to an URL and displays the response header data and the first 10 lines of
 * the requested data.
 * 
 * Supply the URL and an optional username and password (for HTTP basic authentication) on the
 * command line.
 * @version 1.11 2007-06-26
 * @author Cay Horstmann
 */
public class URLConnectionTest {
    public static void main(String[] args) {
        try {
            String urlName;
            if (args.length > 0)
                urlName = args[0];
            else
                urlName = "http://java.sun.com";

            URL url = new URL(urlName);
            URLConnection connection = url.openConnection();

            // set username, password if specified on command line

            if (args.length > 2) {
                String username = args[1];
                String password = args[2];
                String input = username + ":" + password;
                String encoding = base64Encode(input);
                connection.setRequestProperty("Authorization", "Basic " + encoding);
            }

            connection.connect();

            // print header fields

            Map<String, List<String>> headers = connection.getHeaderFields();
            for (Map.Entry<String, List<String>> entry : headers.entrySet()) {
                String key = entry.getKey();
                for (String value : entry.getValue())
                    System.out.println(key + ": " + value);
            }

            // print convenience functions

            System.out.println("----------");
            System.out.println("getContentType: " + connection.getContentType());
            System.out.println("getContentLength: " + connection.getContentLength());
            System.out.println("getContentEncoding: " + connection.getContentEncoding());
            System.out.println("getDate: " + connection.getDate());
            System.out.println("getExpiration: " + connection.getExpiration());
            System.out.println("getLastModifed: " + connection.getLastModified());
            System.out.println("----------");

            Scanner in = new Scanner(connection.getInputStream());

            // print first ten lines of contents

            for (int n = 1; in.hasNextLine() && n <= 10; n++)
                System.out.println(in.nextLine());
            if (in.hasNextLine())
                System.out.println(". . .");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * Computes the Base64 encoding of a string
     * @param s a string
     * @return the Base 64 encoding of s
     */
    public static String base64Encode(String s) {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        Base64OutputStream out = new Base64OutputStream(bOut);
        try {
            out.write(s.getBytes());
            out.flush();
        } catch (IOException e) {
        }
        return bOut.toString();
    }
}

/**
 * This stream filter converts a stream of bytes to their Base64 encoding.
 * 
 * Base64 encoding encodes 3 bytes into 4 characters. |11111122|22223333|33444444| Each set of 6
 * bits is encoded according to the toBase64 map. If the number of input bytes is not a multiple of
 * 3, then the last group of 4 characters is padded with one or two = signs. Each output line is at
 * most 76 characters.
 */
class Base64OutputStream extends FilterOutputStream {
    /**
     * Constructs the stream filter
     * @param out the stream to filter
     */
    public Base64OutputStream(OutputStream out) {
        super(out);
    }

    public void write(int c) throws IOException {
        inbuf[i] = c;
        i++;
        if (i == 3) {
            super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
            super.write(toBase64[((inbuf[0] & 0x03) << 4) | ((inbuf[1] & 0xF0) >> 4)]);
            super.write(toBase64[((inbuf[1] & 0x0F) << 2) | ((inbuf[2] & 0xC0) >> 6)]);
            super.write(toBase64[inbuf[2] & 0x3F]);
            col += 4;
            i = 0;
            if (col >= 76) {
                super.write('\n');
                col = 0;
            }
        }
    }

    public void flush() throws IOException {
        if (i == 1) {
            super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
            super.write(toBase64[(inbuf[0] & 0x03) << 4]);
            super.write('=');
            super.write('=');
        } else if (i == 2) {
            super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
            super.write(toBase64[((inbuf[0] & 0x03) << 4) | ((inbuf[1] & 0xF0) >> 4)]);
            super.write(toBase64[(inbuf[1] & 0x0F) << 2]);
            super.write('=');
        }
        if (col > 0) {
            super.write('\n');
            col = 0;
        }
    }

    private static char[] toBase64 = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
            'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
            'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4',
            '5', '6', '7', '8', '9', '+', '/' };

    private int col = 0;
    private int i = 0;
    private int[] inbuf = new int[3];
}