| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 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 | */ |
| 16 | package org.springframework.batch.item.file; |
| 17 | |
| 18 | import java.io.BufferedReader; |
| 19 | import java.io.IOException; |
| 20 | import java.io.InputStreamReader; |
| 21 | import java.io.Reader; |
| 22 | import java.io.UnsupportedEncodingException; |
| 23 | |
| 24 | import org.springframework.core.io.Resource; |
| 25 | |
| 26 | /** |
| 27 | * A {@link BufferedReaderFactory} useful for reading simple binary (or text) |
| 28 | * files with no line endings, such as those produced by mainframe copy books. |
| 29 | * The reader splits a stream up across fixed line endings (rather than the |
| 30 | * usual convention based on plain text). The line endings are discarded, just |
| 31 | * as with the default plain text implementation. |
| 32 | * |
| 33 | * @author Dave Syer |
| 34 | * |
| 35 | * @since 2.1 |
| 36 | */ |
| 37 | public class SimpleBinaryBufferedReaderFactory implements BufferedReaderFactory { |
| 38 | |
| 39 | /** |
| 40 | * The default line ending value. |
| 41 | */ |
| 42 | private static final String DEFAULT_LINE_ENDING = "\n"; |
| 43 | |
| 44 | private String lineEnding = DEFAULT_LINE_ENDING; |
| 45 | |
| 46 | /** |
| 47 | * @param lineEnding |
| 48 | */ |
| 49 | public void setLineEnding(String lineEnding) { |
| 50 | this.lineEnding = lineEnding; |
| 51 | } |
| 52 | |
| 53 | public BufferedReader create(Resource resource, String encoding) throws UnsupportedEncodingException, IOException { |
| 54 | return new BinaryBufferedReader(new InputStreamReader(resource.getInputStream(), encoding), lineEnding); |
| 55 | } |
| 56 | |
| 57 | /** |
| 58 | * BufferedReader extension that splits lines based on a line ending, rather |
| 59 | * than the usual plain text conventions. |
| 60 | * |
| 61 | * @author Dave Syer |
| 62 | * |
| 63 | */ |
| 64 | private final class BinaryBufferedReader extends BufferedReader { |
| 65 | |
| 66 | private final String ending; |
| 67 | |
| 68 | /** |
| 69 | * @param in |
| 70 | */ |
| 71 | private BinaryBufferedReader(Reader in, String ending) { |
| 72 | super(in); |
| 73 | this.ending = ending; |
| 74 | } |
| 75 | |
| 76 | @Override |
| 77 | public String readLine() throws IOException { |
| 78 | |
| 79 | StringBuilder buffer = null; |
| 80 | |
| 81 | synchronized (lock) { |
| 82 | |
| 83 | int next = read(); |
| 84 | if (next == -1) { |
| 85 | return null; |
| 86 | } |
| 87 | |
| 88 | buffer = new StringBuilder(); |
| 89 | StringBuilder candidateEnding = new StringBuilder(); |
| 90 | |
| 91 | while (!isEndOfLine(buffer, candidateEnding, next)) { |
| 92 | next = read(); |
| 93 | } |
| 94 | buffer.append(candidateEnding); |
| 95 | |
| 96 | } |
| 97 | |
| 98 | if (buffer != null && buffer.length() > 0) { |
| 99 | return buffer.toString(); |
| 100 | } |
| 101 | return null; |
| 102 | |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * Check for end of line and accumulate a buffer for next time. |
| 107 | * |
| 108 | * @param buffer the current line excluding the candidate ending |
| 109 | * @param candidate a buffer containing accumulated state |
| 110 | * @param next the next character (or -1 for end of file) |
| 111 | * @return true if the values together signify the end of a file |
| 112 | */ |
| 113 | private boolean isEndOfLine(StringBuilder buffer, StringBuilder candidate, int next) { |
| 114 | |
| 115 | if (next == -1) { |
| 116 | return true; |
| 117 | } |
| 118 | |
| 119 | char c = (char) next; |
| 120 | if (ending.charAt(0) == c || candidate.length() > 0) { |
| 121 | candidate.append(c); |
| 122 | } |
| 123 | |
| 124 | if (candidate.length() == 0) { |
| 125 | buffer.append(c); |
| 126 | return false; |
| 127 | } |
| 128 | |
| 129 | boolean end = ending.equals(candidate.toString()); |
| 130 | if (end) { |
| 131 | candidate.delete(0, candidate.length()); |
| 132 | } |
| 133 | else if (candidate.length() >= ending.length()) { |
| 134 | buffer.append(candidate); |
| 135 | candidate.delete(0, candidate.length()); |
| 136 | } |
| 137 | |
| 138 | return end; |
| 139 | |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | } |