URLEncoder.java revision 55392539fea537abfb6581b474918f9d611fba27 
1/*
2 *  Licensed to the Apache Software Foundation (ASF) under one or more
3 *  contributor license agreements.  See the NOTICE file distributed with
4 *  this work for additional information regarding copyright ownership.
5 *  The ASF licenses this file to You under the Apache License, Version 2.0
6 *  (the "License"); you may not use this file except in compliance with
7 *  the License.  You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 *  Unless required by applicable law or agreed to in writing, software
12 *  distributed under the License is distributed on an "AS IS" BASIS,
13 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 *  See the License for the specific language governing permissions and
15 *  limitations under the License.
16 */
17
18package java.net;
19
20import java.io.UnsupportedEncodingException;
21
22/**
23 * This class is used to encode a string using the format required by
24 * {@code application/x-www-form-urlencoded} MIME content type.
25 */
26public class URLEncoder {
27
28    static final String digits = "0123456789ABCDEF"; //$NON-NLS-1$
29
30    /**
31     * Prevents this class from being instantiated.
32     */
33    private URLEncoder() {
34    }
35
36    /**
37     * Encodes a given string {@code s} in a x-www-form-urlencoded string using
38     * the specified encoding scheme {@code enc}.
39     * <p>
40     * All characters except letters ('a'..'z', 'A'..'Z') and numbers ('0'..'9')
41     * and characters '.', '-', '*', '_' are converted into their hexadecimal
42     * value prepended by '%'. For example: '#' -> %23. In addition, spaces are
43     * substituted by '+'
44     *
45     * @param s
46     *            the string to be encoded.
47     * @return the encoded string.
48     * @deprecated use {@link #encode(String, String)} instead.
49     */
50    @Deprecated
51    public static String encode(String s) {
52        // Guess a bit bigger for encoded form
53        StringBuilder buf = new StringBuilder(s.length() + 16);
54        for (int i = 0; i < s.length(); i++) {
55            char ch = s.charAt(i);
56            if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')
57                    || (ch >= '0' && ch <= '9') || ".-*_".indexOf(ch) > -1) { //$NON-NLS-1$
58                buf.append(ch);
59            } else if (ch == ' ') {
60                buf.append('+');
61            } else {
62                byte[] bytes = new String(new char[] { ch }).getBytes();
63                for (int j = 0; j < bytes.length; j++) {
64                    buf.append('%');
65                    buf.append(digits.charAt((bytes[j] & 0xf0) >> 4));
66                    buf.append(digits.charAt(bytes[j] & 0xf));
67                }
68            }
69        }
70        return buf.toString();
71    }
72
73    /**
74     * Encodes the given string {@code s} in a x-www-form-urlencoded string
75     * using the specified encoding scheme {@code enc}.
76     * <p>
77     * All characters except letters ('a'..'z', 'A'..'Z') and numbers ('0'..'9')
78     * and characters '.', '-', '*', '_' are converted into their hexadecimal
79     * value prepended by '%'. For example: '#' -> %23. In addition, spaces are
80     * substituted by '+'
81     *
82     * @param s
83     *            the string to be encoded.
84     * @param enc
85     *            the encoding scheme to be used.
86     * @return the encoded string.
87     * @throws UnsupportedEncodingException
88     *             if the specified encoding scheme is invalid.
89     */
90    public static String encode(String s, String enc)
91            throws UnsupportedEncodingException {
92
93        if (s == null || enc == null) {
94            throw new NullPointerException();
95        }
96        // check for UnsupportedEncodingException
97        "".getBytes(enc); //$NON-NLS-1$
98
99        // Guess a bit bigger for encoded form
100        StringBuffer buf = new StringBuffer(s.length() + 16);
101        int start = -1;
102        for (int i = 0; i < s.length(); i++) {
103            char ch = s.charAt(i);
104            if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')
105                    || (ch >= '0' && ch <= '9') || " .-*_".indexOf(ch) > -1) { //$NON-NLS-1$
106                if (start >= 0) {
107                    convert(s.substring(start, i), buf, enc);
108                    start = -1;
109                }
110                if (ch != ' ') {
111                    buf.append(ch);
112                } else {
113                    buf.append('+');
114                }
115            } else {
116                if (start < 0) {
117                    start = i;
118                }
119            }
120        }
121        if (start >= 0) {
122            convert(s.substring(start, s.length()), buf, enc);
123        }
124        return buf.toString();
125    }
126
127    private static void convert(String s, StringBuffer buf, String enc)
128            throws UnsupportedEncodingException {
129        byte[] bytes = s.getBytes(enc);
130        for (int j = 0; j < bytes.length; j++) {
131            buf.append('%');
132            buf.append(digits.charAt((bytes[j] & 0xf0) >> 4));
133            buf.append(digits.charAt(bytes[j] & 0xf));
134        }
135    }
136}
137