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 018package org.apache.commons.net.io; 019 020import java.io.FilterOutputStream; 021import java.io.IOException; 022import java.io.OutputStream; 023 024/** 025 * This class wraps an output stream, replacing all occurrences of <CR><LF> (carriage return followed by a linefeed), which is the NETASCII standard 026 * for representing a newline, with the local line separator representation. You would use this class to implement ASCII file transfers requiring conversion 027 * from NETASCII. 028 * <p> 029 * Because of the translation process, a call to <code>flush()</code> will not flush the last byte written if that byte was a carriage return. A call to 030 * {@link #close close() }, however, will flush the carriage return. 031 * 032 * 033 */ 034 035public final class FromNetASCIIOutputStream extends FilterOutputStream { 036 private boolean lastWasCR; 037 038 /** 039 * Creates a FromNetASCIIOutputStream instance that wraps an existing OutputStream. 040 * 041 * @param output The OutputStream to wrap. 042 */ 043 public FromNetASCIIOutputStream(final OutputStream output) { 044 super(output); 045 lastWasCR = false; 046 } 047 048 /** 049 * Closes the stream, writing all pending data. 050 * 051 * @throws IOException If an error occurs while closing the stream. 052 */ 053 @Override 054 public synchronized void close() throws IOException { 055 if (FromNetASCIIInputStream._noConversionRequired) { 056 super.close(); 057 return; 058 } 059 060 if (lastWasCR) { 061 out.write('\r'); 062 } 063 super.close(); 064 } 065 066 /** 067 * Writes a byte array to the stream. 068 * 069 * @param buffer The byte array to write. 070 * @throws IOException If an error occurs while writing to the underlying stream. 071 */ 072 @Override 073 public synchronized void write(final byte buffer[]) throws IOException { 074 write(buffer, 0, buffer.length); 075 } 076 077 /** 078 * Writes a number of bytes from a byte array to the stream starting from a given offset. 079 * 080 * @param buffer The byte array to write. 081 * @param offset The offset into the array at which to start copying data. 082 * @param length The number of bytes to write. 083 * @throws IOException If an error occurs while writing to the underlying stream. 084 */ 085 @Override 086 public synchronized void write(final byte buffer[], int offset, int length) throws IOException { 087 if (FromNetASCIIInputStream._noConversionRequired) { 088 // FilterOutputStream method is very slow. 089 // super.write(buffer, offset, length); 090 out.write(buffer, offset, length); 091 return; 092 } 093 094 while (length-- > 0) { 095 writeInt(buffer[offset++]); 096 } 097 } 098 099 /** 100 * Writes a byte to the stream. Note that a call to this method might not actually write a byte to the underlying stream until a subsequent character is 101 * written, from which it can be determined if a NETASCII line separator was encountered. This is transparent to the programmer and is only mentioned for 102 * completeness. 103 * 104 * @param ch The byte to write. 105 * @throws IOException If an error occurs while writing to the underlying stream. 106 */ 107 @Override 108 public synchronized void write(final int ch) throws IOException { 109 if (FromNetASCIIInputStream._noConversionRequired) { 110 out.write(ch); 111 return; 112 } 113 114 writeInt(ch); 115 } 116 117 private void writeInt(final int ch) throws IOException { 118 switch (ch) { 119 case '\r': 120 lastWasCR = true; 121 // Don't write anything. We need to see if next one is linefeed 122 break; 123 case '\n': 124 if (lastWasCR) { 125 out.write(FromNetASCIIInputStream._lineSeparatorBytes); 126 lastWasCR = false; 127 break; 128 } 129 out.write('\n'); 130 break; 131 default: 132 if (lastWasCR) { 133 out.write('\r'); 134 lastWasCR = false; 135 } 136 out.write(ch); 137 break; 138 } 139 } 140}