| 1 | package be.nikiroo.utils.streams; |
| 2 | |
| 3 | import java.io.IOException; |
| 4 | import java.io.InputStream; |
| 5 | |
| 6 | /** |
| 7 | * This {@link InputStream} will change some of its content by replacing it with |
| 8 | * something else. |
| 9 | * |
| 10 | * @author niki |
| 11 | */ |
| 12 | public class ReplaceInputStream extends BufferedInputStream { |
| 13 | private byte[][] froms; |
| 14 | private byte[][] tos; |
| 15 | private int maxToSize; |
| 16 | |
| 17 | private byte[] source; |
| 18 | private int spos; |
| 19 | private int slen; |
| 20 | |
| 21 | /** |
| 22 | * Create a {@link ReplaceInputStream} that will replace <tt>from</tt> with |
| 23 | * <tt>to</tt>. |
| 24 | * |
| 25 | * @param in |
| 26 | * the under-laying {@link InputStream} |
| 27 | * @param from |
| 28 | * the {@link String} to replace |
| 29 | * @param to |
| 30 | * the {@link String} to replace with |
| 31 | */ |
| 32 | public ReplaceInputStream(InputStream in, String from, String to) { |
| 33 | this(in, StreamUtils.bytes(from), StreamUtils.bytes(to)); |
| 34 | } |
| 35 | |
| 36 | /** |
| 37 | * Create a {@link ReplaceInputStream} that will replace <tt>from</tt> with |
| 38 | * <tt>to</tt>. |
| 39 | * |
| 40 | * @param in |
| 41 | * the under-laying {@link InputStream} |
| 42 | * @param from |
| 43 | * the value to replace |
| 44 | * @param to |
| 45 | * the value to replace with |
| 46 | */ |
| 47 | public ReplaceInputStream(InputStream in, byte[] from, byte[] to) { |
| 48 | this(in, new byte[][] { from }, new byte[][] { to }); |
| 49 | } |
| 50 | |
| 51 | /** |
| 52 | * Create a {@link ReplaceInputStream} that will replace all <tt>froms</tt> |
| 53 | * with <tt>tos</tt>. |
| 54 | * <p> |
| 55 | * Note that they will be replaced in order, and that for each <tt>from</tt> |
| 56 | * a <tt>to</tt> must correspond. |
| 57 | * |
| 58 | * @param in |
| 59 | * the under-laying {@link InputStream} |
| 60 | * @param froms |
| 61 | * the values to replace |
| 62 | * @param tos |
| 63 | * the values to replace with |
| 64 | */ |
| 65 | public ReplaceInputStream(InputStream in, String[] froms, String[] tos) { |
| 66 | this(in, StreamUtils.bytes(froms), StreamUtils.bytes(tos)); |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Create a {@link ReplaceInputStream} that will replace all <tt>froms</tt> |
| 71 | * with <tt>tos</tt>. |
| 72 | * <p> |
| 73 | * Note that they will be replaced in order, and that for each <tt>from</tt> |
| 74 | * a <tt>to</tt> must correspond. |
| 75 | * |
| 76 | * @param in |
| 77 | * the under-laying {@link InputStream} |
| 78 | * @param froms |
| 79 | * the values to replace |
| 80 | * @param tos |
| 81 | * the values to replace with |
| 82 | */ |
| 83 | public ReplaceInputStream(InputStream in, byte[][] froms, byte[][] tos) { |
| 84 | super(in); |
| 85 | |
| 86 | if (froms.length != tos.length) { |
| 87 | throw new IllegalArgumentException( |
| 88 | "For replacing, each FROM must have a corresponding TO"); |
| 89 | } |
| 90 | |
| 91 | this.froms = froms; |
| 92 | this.tos = tos; |
| 93 | |
| 94 | for (int i = 0; i < tos.length; i++) { |
| 95 | maxToSize = Math.max(maxToSize, tos[i].length); |
| 96 | } |
| 97 | |
| 98 | source = new byte[4096]; |
| 99 | spos = 0; |
| 100 | slen = 0; |
| 101 | } |
| 102 | |
| 103 | @Override |
| 104 | protected int read(InputStream in, byte[] buffer, int off, int len) |
| 105 | throws IOException { |
| 106 | if (len < maxToSize || source.length < maxToSize * 2) { |
| 107 | throw new IOException( |
| 108 | "An underlaying buffer is too small for these replace values"); |
| 109 | } |
| 110 | |
| 111 | if (spos >= slen) { |
| 112 | spos = 0; |
| 113 | slen = in.read(source); |
| 114 | } |
| 115 | |
| 116 | // Note: very simple, not efficient implementation, sorry. |
| 117 | int count = 0; |
| 118 | while (spos < slen && count < len - maxToSize) { |
| 119 | boolean replaced = false; |
| 120 | for (int i = 0; i < froms.length; i++) { |
| 121 | if (froms[i] != null && froms[i].length > 0 |
| 122 | && StreamUtils.startsWith(froms[i], source, spos, slen)) { |
| 123 | if (tos[i] != null && tos[i].length > 0) { |
| 124 | System.arraycopy(tos[i], 0, buffer, off + spos, |
| 125 | tos[i].length); |
| 126 | count += tos[i].length; |
| 127 | } |
| 128 | |
| 129 | spos += froms[i].length; |
| 130 | replaced = true; |
| 131 | break; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | if (!replaced) { |
| 136 | buffer[off + count++] = source[spos++]; |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | return count; |
| 141 | } |
| 142 | } |