001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 018 package org.apache.commons.net.io; 019 020 import java.io.FilterInputStream; 021 import java.io.IOException; 022 import java.io.InputStream; 023 024 /*** 025 * This class wraps an input stream, replacing all singly occurring 026 * <LF> (linefeed) characters with <CR><LF> (carriage return 027 * followed by linefeed), which is the NETASCII standard for representing 028 * a newline. 029 * You would use this class to implement ASCII file transfers requiring 030 * conversion to NETASCII. 031 * <p> 032 * <p> 033 * @author Daniel F. Savarese 034 ***/ 035 036 public final class ToNetASCIIInputStream extends FilterInputStream 037 { 038 private static final int __NOTHING_SPECIAL = 0; 039 private static final int __LAST_WAS_CR = 1; 040 private static final int __LAST_WAS_NL = 2; 041 private int __status; 042 043 /*** 044 * Creates a ToNetASCIIInputStream instance that wraps an existing 045 * InputStream. 046 * <p> 047 * @param input The InputStream to . 048 ***/ 049 public ToNetASCIIInputStream(InputStream input) 050 { 051 super(input); 052 __status = __NOTHING_SPECIAL; 053 } 054 055 056 /*** 057 * Reads and returns the next byte in the stream. If the end of the 058 * message has been reached, returns -1. 059 * <p> 060 * @return The next character in the stream. Returns -1 if the end of the 061 * stream has been reached. 062 * @exception IOException If an error occurs while reading the underlying 063 * stream. 064 ***/ 065 @Override 066 public int read() throws IOException 067 { 068 int ch; 069 070 if (__status == __LAST_WAS_NL) 071 { 072 __status = __NOTHING_SPECIAL; 073 return '\n'; 074 } 075 076 ch = in.read(); 077 078 switch (ch) 079 { 080 case '\r': 081 __status = __LAST_WAS_CR; 082 return '\r'; 083 case '\n': 084 if (__status != __LAST_WAS_CR) 085 { 086 __status = __LAST_WAS_NL; 087 return '\r'; 088 } 089 //$FALL-THROUGH$ 090 default: 091 __status = __NOTHING_SPECIAL; 092 return ch; 093 } 094 // statement not reached 095 //return ch; 096 } 097 098 099 /*** 100 * Reads the next number of bytes from the stream into an array and 101 * returns the number of bytes read. Returns -1 if the end of the 102 * stream has been reached. 103 * <p> 104 * @param buffer The byte array in which to store the data. 105 * @return The number of bytes read. Returns -1 if the 106 * end of the message has been reached. 107 * @exception IOException If an error occurs in reading the underlying 108 * stream. 109 ***/ 110 @Override 111 public int read(byte buffer[]) throws IOException 112 { 113 return read(buffer, 0, buffer.length); 114 } 115 116 117 /*** 118 * Reads the next number of bytes from the stream into an array and returns 119 * the number of bytes read. Returns -1 if the end of the 120 * message has been reached. The characters are stored in the array 121 * starting from the given offset and up to the length specified. 122 * <p> 123 * @param buffer The byte array in which to store the data. 124 * @param offset The offset into the array at which to start storing data. 125 * @param length The number of bytes to read. 126 * @return The number of bytes read. Returns -1 if the 127 * end of the stream has been reached. 128 * @exception IOException If an error occurs while reading the underlying 129 * stream. 130 ***/ 131 @Override 132 public int read(byte buffer[], int offset, int length) throws IOException 133 { 134 int ch, off; 135 136 if (length < 1) 137 return 0; 138 139 ch = available(); 140 141 if (length > ch) 142 length = ch; 143 144 // If nothing is available, block to read only one character 145 if (length < 1) 146 length = 1; 147 148 if ((ch = read()) == -1) 149 return -1; 150 151 off = offset; 152 153 do 154 { 155 buffer[offset++] = (byte)ch; 156 } 157 while (--length > 0 && (ch = read()) != -1); 158 159 return (offset - off); 160 } 161 162 /*** Returns false. Mark is not supported. ***/ 163 @Override 164 public boolean markSupported() 165 { 166 return false; 167 } 168 169 @Override 170 public int available() throws IOException 171 { 172 int result; 173 174 result = in.available(); 175 176 if (__status == __LAST_WAS_NL) 177 return (result + 1); 178 179 return result; 180 } 181 }