Add java.net.URLEncoder

Author: peterschrammel

src/main/java/java/net/URLEncoder.java

@@ -0,0 +1,292 @@
+/*
+ * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.net;
+
+import java.io.ByteArrayOutputStream;
+import java.io.BufferedWriter;
+import java.io.OutputStreamWriter;
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.io.CharArrayWriter;
+import java.nio.charset.Charset;
+import java.nio.charset.IllegalCharsetNameException;
+import java.nio.charset.UnsupportedCharsetException ;
+import java.util.BitSet;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import sun.security.action.GetBooleanAction;
+import sun.security.action.GetPropertyAction;
+
+/**
+ * Utility class for HTML form encoding. This class contains static methods
+ * for converting a String to the <CODE>application/x-www-form-urlencoded</CODE> MIME
+ * format. For more information about HTML form encoding, consult the HTML
+ * <A HREF="http://www.w3.org/TR/html4/">specification</A>.
+ *
+ * <p>
+ * When encoding a String, the following rules apply:
+ *
+ * <ul>
+ * <li>The alphanumeric characters &quot;{@code a}&quot; through
+ *     &quot;{@code z}&quot;, &quot;{@code A}&quot; through
+ *     &quot;{@code Z}&quot; and &quot;{@code 0}&quot;
+ *     through &quot;{@code 9}&quot; remain the same.
+ * <li>The special characters &quot;{@code .}&quot;,
+ *     &quot;{@code -}&quot;, &quot;{@code *}&quot;, and
+ *     &quot;{@code _}&quot; remain the same.
+ * <li>The space character &quot; &nbsp; &quot; is
+ *     converted into a plus sign &quot;{@code +}&quot;.
+ * <li>All other characters are unsafe and are first converted into
+ *     one or more bytes using some encoding scheme. Then each byte is
+ *     represented by the 3-character string
+ *     &quot;<i>{@code %xy}</i>&quot;, where <i>xy</i> is the
+ *     two-digit hexadecimal representation of the byte.
+ *     The recommended encoding scheme to use is UTF-8. However,
+ *     for compatibility reasons, if an encoding is not specified,
+ *     then the default encoding of the platform is used.
+ * </ul>
+ *
+ * <p>
+ * For example using UTF-8 as the encoding scheme the string &quot;The
+ * string &#252;@foo-bar&quot; would get converted to
+ * &quot;The+string+%C3%BC%40foo-bar&quot; because in UTF-8 the character
+ * &#252; is encoded as two bytes C3 (hex) and BC (hex), and the
+ * character @ is encoded as one byte 40 (hex).
+ *
+ * @author  Herb Jellinek
+ * @since   JDK1.0
+ */
+public class URLEncoder {
+    static BitSet dontNeedEncoding;
+    static final int caseDiff = ('a' - 'A');
+    static String dfltEncName = null;
+
+    static {
+
+        /* The list of characters that are not encoded has been
+         * determined as follows:
+         *
+         * RFC 2396 states:
+         * -----
+         * Data characters that are allowed in a URI but do not have a
+         * reserved purpose are called unreserved.  These include upper
+         * and lower case letters, decimal digits, and a limited set of
+         * punctuation marks and symbols.
+         *
+         * unreserved  = alphanum | mark
+         *
+         * mark        = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")"
+         *
+         * Unreserved characters can be escaped without changing the
+         * semantics of the URI, but this should not be done unless the
+         * URI is being used in a context that does not allow the
+         * unescaped character to appear.
+         * -----
+         *
+         * It appears that both Netscape and Internet Explorer escape
+         * all special characters from this list with the exception
+         * of "-", "_", ".", "*". While it is not clear why they are
+         * escaping the other characters, perhaps it is safest to
+         * assume that there might be contexts in which the others
+         * are unsafe if not escaped. Therefore, we will use the same
+         * list. It is also noteworthy that this is consistent with
+         * O'Reilly's "HTML: The Definitive Guide" (page 164).
+         *
+         * As a last note, Intenet Explorer does not encode the "@"
+         * character which is clearly not unreserved according to the
+         * RFC. We are being consistent with the RFC in this matter,
+         * as is Netscape.
+         *
+         */
+
+        dontNeedEncoding = new BitSet(256);
+        int i;
+        for (i = 'a'; i <= 'z'; i++) {
+            dontNeedEncoding.set(i);
+        }
+        for (i = 'A'; i <= 'Z'; i++) {
+            dontNeedEncoding.set(i);
+        }
+        for (i = '0'; i <= '9'; i++) {
+            dontNeedEncoding.set(i);
+        }
+        dontNeedEncoding.set(' '); /* encoding a space to a + is done
+                                    * in the encode() method */
+        dontNeedEncoding.set('-');
+        dontNeedEncoding.set('_');
+        dontNeedEncoding.set('.');
+        dontNeedEncoding.set('*');
+
+        dfltEncName = AccessController.doPrivileged(
+            new GetPropertyAction("file.encoding")
+        );
+    }
+
+    /**
+     * You can't call the constructor.
+     */
+    private URLEncoder() { }
+
+    /**
+     * Translates a string into {@code x-www-form-urlencoded}
+     * format. This method uses the platform's default encoding
+     * as the encoding scheme to obtain the bytes for unsafe characters.
+     *
+     * @param   s   {@code String} to be translated.
+     * @deprecated The resulting string may vary depending on the platform's
+     *             default encoding. Instead, use the encode(String,String)
+     *             method to specify the encoding.
+     * @return  the translated {@code String}.
+     */
+    @Deprecated
+    public static String encode(String s) {
+
+        String str = null;
+
+        try {
+            str = encode(s, dfltEncName);
+        } catch (UnsupportedEncodingException e) {
+            // The system should always have the platform default
+        }
+
+        return str;
+    }
+
+    /**
+     * Translates a string into {@code application/x-www-form-urlencoded}
+     * format using a specific encoding scheme. This method uses the
+     * supplied encoding scheme to obtain the bytes for unsafe
+     * characters.
+     * <p>
+     * <em><strong>Note:</strong> The <a href=
+     * "http://www.w3.org/TR/html40/appendix/notes.html#non-ascii-chars">
+     * World Wide Web Consortium Recommendation</a> states that
+     * UTF-8 should be used. Not doing so may introduce
+     * incompatibilities.</em>
+     *
+     * @param   s   {@code String} to be translated.
+     * @param   enc   The name of a supported
+     *    <a href="../lang/package-summary.html#charenc">character
+     *    encoding</a>.
+     * @return  the translated {@code String}.
+     * @exception  UnsupportedEncodingException
+     *             If the named encoding is not supported
+     * @see URLDecoder#decode(java.lang.String, java.lang.String)
+     * @since 1.4
+     */
+    public static String encode(String s, String enc)
+        throws UnsupportedEncodingException {
+
+        boolean needToChange = false;
+        StringBuffer out = new StringBuffer(s.length());
+        Charset charset;
+        CharArrayWriter charArrayWriter = new CharArrayWriter();
+
+        if (enc == null)
+            throw new NullPointerException("charsetName");
+
+        try {
+            charset = Charset.forName(enc);
+        } catch (IllegalCharsetNameException e) {
+            throw new UnsupportedEncodingException(enc);
+        } catch (UnsupportedCharsetException e) {
+            throw new UnsupportedEncodingException(enc);
+        }
+
+        for (int i = 0; i < s.length();) {
+            int c = (int) s.charAt(i);
+            //System.out.println("Examining character: " + c);
+            if (dontNeedEncoding.get(c)) {
+                if (c == ' ') {
+                    c = '+';
+                    needToChange = true;
+                }
+                //System.out.println("Storing: " + c);
+                out.append((char)c);
+                i++;
+            } else {
+                // convert to external encoding before hex conversion
+                do {
+                    charArrayWriter.write(c);
+                    /*
+                     * If this character represents the start of a Unicode
+                     * surrogate pair, then pass in two characters. It's not
+                     * clear what should be done if a bytes reserved in the
+                     * surrogate pairs range occurs outside of a legal
+                     * surrogate pair. For now, just treat it as if it were
+                     * any other character.
+                     */
+                    if (c >= 0xD800 && c <= 0xDBFF) {
+                        /*
+                          System.out.println(Integer.toHexString(c)
+                          + " is high surrogate");
+                        */
+                        if ( (i+1) < s.length()) {
+                            int d = (int) s.charAt(i+1);
+                            /*
+                              System.out.println("\tExamining "
+                              + Integer.toHexString(d));
+                            */
+                            if (d >= 0xDC00 && d <= 0xDFFF) {
+                                /*
+                                  System.out.println("\t"
+                                  + Integer.toHexString(d)
+                                  + " is low surrogate");
+                                */
+                                charArrayWriter.write(d);
+                                i++;
+                            }
+                        }
+                    }
+                    i++;
+                } while (i < s.length() && !dontNeedEncoding.get((c = (int) s.charAt(i))));
+
+                charArrayWriter.flush();
+                String str = new String(charArrayWriter.toCharArray());
+                byte[] ba = str.getBytes(charset);
+                for (int j = 0; j < ba.length; j++) {
+                    out.append('%');
+                    char ch = Character.forDigit((ba[j] >> 4) & 0xF, 16);
+                    // converting to use uppercase letter as part of
+                    // the hex value if ch is a letter.
+                    if (Character.isLetter(ch)) {
+                        ch -= caseDiff;
+                    }
+                    out.append(ch);
+                    ch = Character.forDigit(ba[j] & 0xF, 16);
+                    if (Character.isLetter(ch)) {
+                        ch -= caseDiff;
+                    }
+                    out.append(ch);
+                }
+                charArrayWriter.reset();
+                needToChange = true;
+            }
+        }
+
+        return (needToChange? out.toString() : s);
+    }
+}