Initial revision

From-SVN: r102074

libjava/classpath/java/net/URLDecoder.java

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+/* URLDecoder.java -- Class to decode URL's from encoded form.
+   Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath 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 2, or (at your option)
+any later version.
+
+GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.net;
+
+import java.io.UnsupportedEncodingException;
+
+
+/**
+ * This utility class contains static methods that converts a
+ * string encoded in the x-www-form-urlencoded format to the original
+ * text.  The x-www-form-urlencoded format replaces certain disallowed
+ * characters with encoded equivalents.  All upper case and lower case
+ * letters in the US alphabet remain as is, the space character (' ')
+ * is replaced with '+' sign, and all other characters are converted to a
+ * "%XX" format where XX is the hexadecimal representation of that character
+ * in a given character encoding (default is "UTF-8").
+ * <p>
+ * This method is very useful for decoding strings sent to CGI scripts
+ *
+ * Written using on-line Java Platform 1.2/1.4 API Specification.
+ * Status:  Believed complete and correct.
+ *
+ * @since 1.2
+ *
+ * @author Warren Levy (warrenl@cygnus.com)
+ * @author Aaron M. Renn (arenn@urbanophile.com) (documentation comments)
+ * @author Mark Wielaard (mark@klomp.org)
+ */
+public class URLDecoder
+{
+  /**
+   * Public contructor. Note that this class has only static methods.
+   */
+  public URLDecoder()
+  {
+  }
+
+  /**
+   * This method translates the passed in string from x-www-form-urlencoded
+   * format using the default encoding "UTF-8" to decode the hex encoded
+   * unsafe characters.
+   *
+   * @param s the String to convert
+   *
+   * @return the converted String
+   *
+   * @deprecated
+   */
+  public static String decode(String s)
+  {
+    try
+      {
+	return decode(s, "UTF-8");
+      }
+    catch (UnsupportedEncodingException uee)
+      {
+	// Should never happen since UTF-8 encoding should always be supported
+	return s;
+      }
+  }
+
+  /**
+   * This method translates the passed in string from x-www-form-urlencoded
+   * format using the given character encoding to decode the hex encoded
+   * unsafe characters.
+   *
+   * This implementation will decode the string even if it contains
+   * unsafe characters (characters that should have been encoded) or if the
+   * two characters following a % do not represent a hex encoded byte.
+   * In those cases the unsafe character or the % character will be added
+   * verbatim to the decoded result.
+   *
+   * @param s the String to convert
+   * @param encoding the character encoding to use the decode the hex encoded
+   *        unsafe characters
+   *
+   * @return the converted String
+   *
+   * @exception UnsupportedEncodingException If the named encoding is not
+   * supported
+   *
+   * @since 1.4
+   */
+  public static String decode(String s, String encoding)
+    throws UnsupportedEncodingException
+  {
+    // First convert all '+' characters to spaces.
+    String str = s.replace('+', ' ');
+
+    // Then go through the whole string looking for byte encoded characters
+    int i;
+    int start = 0;
+    byte[] bytes = null;
+    int length = str.length();
+    StringBuffer result = new StringBuffer(length);
+    while ((i = str.indexOf('%', start)) >= 0)
+      {
+	// Add all non-encoded characters to the result buffer
+	result.append(str.substring(start, i));
+	start = i;
+
+	// Get all consecutive encoded bytes
+	while ((i + 2 < length) && (str.charAt(i) == '%'))
+	  i += 3;
+
+	// Decode all these bytes
+	if ((bytes == null) || (bytes.length < ((i - start) / 3)))
+	  bytes = new byte[((i - start) / 3)];
+
+	int index = 0;
+	try
+	  {
+	    while (start < i)
+	      {
+		String sub = str.substring(start + 1, start + 3);
+		bytes[index] = (byte) Integer.parseInt(sub, 16);
+		index++;
+		start += 3;
+	      }
+	  }
+	catch (NumberFormatException nfe)
+	  {
+	    // One of the hex encoded strings was bad
+	  }
+
+	// Add the bytes as characters according to the given encoding
+	result.append(new String(bytes, 0, index, encoding));
+
+	// Make sure we skip to just after a % sign
+	// There might not have been enough encoded characters after the %
+	// or the hex chars were not actually hex chars (NumberFormatException)
+	if (start < length && s.charAt(start) == '%')
+	  {
+	    result.append('%');
+	    start++;
+	  }
+      }
+
+    // Add any characters left
+    if (start < str.length())
+      result.append(str.substring(start));
+
+    return result.toString();
+  }
+} // class URLDecoder