1/**
2 * Copyright (c) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package com.android.phone.common.mail.utils;
17
18import java.io.ByteArrayInputStream;
19import java.nio.ByteBuffer;
20import java.nio.CharBuffer;
21import java.nio.charset.Charset;
22
23/**
24 * Simple utility methods used in email functions.
25 */
26public class Utility {
27    public static final Charset ASCII = Charset.forName("US-ASCII");
28
29    public static final String[] EMPTY_STRINGS = new String[0];
30
31    /**
32     * Returns a concatenated string containing the output of every Object's
33     * toString() method, each separated by the given separator character.
34     */
35    public static String combine(Object[] parts, char separator) {
36        if (parts == null) {
37            return null;
38        }
39        StringBuilder sb = new StringBuilder();
40        for (int i = 0; i < parts.length; i++) {
41            sb.append(parts[i].toString());
42            if (i < parts.length - 1) {
43                sb.append(separator);
44            }
45        }
46        return sb.toString();
47    }
48
49    /** Converts a String to ASCII bytes */
50    public static byte[] toAscii(String s) {
51        return encode(ASCII, s);
52    }
53
54    /** Builds a String from ASCII bytes */
55    public static String fromAscii(byte[] b) {
56        return decode(ASCII, b);
57    }
58
59    private static byte[] encode(Charset charset, String s) {
60        if (s == null) {
61            return null;
62        }
63        final ByteBuffer buffer = charset.encode(CharBuffer.wrap(s));
64        final byte[] bytes = new byte[buffer.limit()];
65        buffer.get(bytes);
66        return bytes;
67    }
68
69    private static String decode(Charset charset, byte[] b) {
70        if (b == null) {
71            return null;
72        }
73        final CharBuffer cb = charset.decode(ByteBuffer.wrap(b));
74        return new String(cb.array(), 0, cb.length());
75    }
76
77    public static ByteArrayInputStream streamFromAsciiString(String ascii) {
78        return new ByteArrayInputStream(toAscii(ascii));
79    }
80}
81