| 1 | package org.apache.velocity.io; |
| 2 | |
| 3 | /* |
| 4 | * Copyright 2000-2001,2004 The Apache Software Foundation. |
| 5 | * |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | * you may not use this file except in compliance with the License. |
| 8 | * You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, software |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | * See the License for the specific language governing permissions and |
| 16 | * limitations under the License. |
| 17 | */ |
| 18 | |
| 19 | import java.io.IOException; |
| 20 | import java.io.Writer; |
| 21 | |
| 22 | /** |
| 23 | * Implementation of a fast Writer. It was originally taken from JspWriter |
| 24 | * and modified to have less syncronization going on. |
| 25 | * |
| 26 | * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> |
| 27 | * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a> |
| 28 | * @author Anil K. Vijendran |
| 29 | * @version $Id: VelocityWriter.java,v 1.8.4.1 2004/03/03 23:22:54 geirm Exp $ |
| 30 | */ |
| 31 | public final class VelocityWriter extends Writer |
| 32 | { |
| 33 | /** |
| 34 | * constant indicating that the Writer is not buffering output |
| 35 | */ |
| 36 | public static final int NO_BUFFER = 0; |
| 37 | |
| 38 | /** |
| 39 | * constant indicating that the Writer is buffered and is using the |
| 40 | * implementation default buffer size |
| 41 | */ |
| 42 | public static final int DEFAULT_BUFFER = -1; |
| 43 | |
| 44 | /** |
| 45 | * constant indicating that the Writer is buffered and is unbounded; |
| 46 | * this is used in BodyContent |
| 47 | */ |
| 48 | public static final int UNBOUNDED_BUFFER = -2; |
| 49 | |
| 50 | protected int bufferSize; |
| 51 | protected boolean autoFlush; |
| 52 | |
| 53 | private Writer writer; |
| 54 | |
| 55 | private char cb[]; |
| 56 | private int nextChar; |
| 57 | |
| 58 | private static int defaultCharBufferSize = 8 * 1024; |
| 59 | |
| 60 | private boolean flushed = false; |
| 61 | |
| 62 | /** |
| 63 | * Create a buffered character-output stream that uses a default-sized |
| 64 | * output buffer. |
| 65 | * |
| 66 | * @param response A Servlet Response |
| 67 | */ |
| 68 | public VelocityWriter(Writer writer) |
| 69 | { |
| 70 | this(writer, defaultCharBufferSize, true); |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * private constructor. |
| 75 | */ |
| 76 | private VelocityWriter(int bufferSize, boolean autoFlush) |
| 77 | { |
| 78 | this.bufferSize = bufferSize; |
| 79 | this.autoFlush = autoFlush; |
| 80 | } |
| 81 | |
| 82 | /** |
| 83 | * This method returns the size of the buffer used by the JspWriter. |
| 84 | * |
| 85 | * @return the size of the buffer in bytes, or 0 is unbuffered. |
| 86 | */ |
| 87 | public int getBufferSize() { return bufferSize; } |
| 88 | |
| 89 | /** |
| 90 | * This method indicates whether the JspWriter is autoFlushing. |
| 91 | * |
| 92 | * @return if this JspWriter is auto flushing or throwing IOExceptions on |
| 93 | * buffer overflow conditions |
| 94 | */ |
| 95 | public boolean isAutoFlush() { return autoFlush; } |
| 96 | |
| 97 | /** |
| 98 | * Create a new buffered character-output stream that uses an output |
| 99 | * buffer of the given size. |
| 100 | * |
| 101 | * @param response A Servlet Response |
| 102 | * @param sz Output-buffer size, a positive integer |
| 103 | * |
| 104 | * @exception IllegalArgumentException If sz is <= 0 |
| 105 | */ |
| 106 | public VelocityWriter(Writer writer, int sz, boolean autoFlush) |
| 107 | { |
| 108 | this(sz, autoFlush); |
| 109 | if (sz < 0) |
| 110 | throw new IllegalArgumentException("Buffer size <= 0"); |
| 111 | this.writer = writer; |
| 112 | cb = sz == 0 ? null : new char[sz]; |
| 113 | nextChar = 0; |
| 114 | } |
| 115 | |
| 116 | private final void init( Writer writer, int sz, boolean autoFlush ) |
| 117 | { |
| 118 | this.writer= writer; |
| 119 | if( sz > 0 && ( cb == null || sz > cb.length ) ) |
| 120 | cb=new char[sz]; |
| 121 | nextChar = 0; |
| 122 | this.autoFlush=autoFlush; |
| 123 | this.bufferSize=sz; |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * Flush the output buffer to the underlying character stream, without |
| 128 | * flushing the stream itself. This method is non-private only so that it |
| 129 | * may be invoked by PrintStream. |
| 130 | */ |
| 131 | private final void flushBuffer() throws IOException |
| 132 | { |
| 133 | if (bufferSize == 0) |
| 134 | return; |
| 135 | flushed = true; |
| 136 | if (nextChar == 0) |
| 137 | return; |
| 138 | writer.write(cb, 0, nextChar); |
| 139 | nextChar = 0; |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * Discard the output buffer. |
| 144 | */ |
| 145 | public final void clear() |
| 146 | { |
| 147 | nextChar = 0; |
| 148 | } |
| 149 | |
| 150 | private final void bufferOverflow() throws IOException |
| 151 | { |
| 152 | throw new IOException("overflow"); |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Flush the stream. |
| 157 | * |
| 158 | */ |
| 159 | public final void flush() throws IOException |
| 160 | { |
| 161 | flushBuffer(); |
| 162 | if (writer != null) |
| 163 | { |
| 164 | writer.flush(); |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | /** |
| 169 | * Close the stream. |
| 170 | * |
| 171 | */ |
| 172 | public final void close() throws IOException { |
| 173 | if (writer == null) |
| 174 | return; |
| 175 | flush(); |
| 176 | } |
| 177 | |
| 178 | /** |
| 179 | * @return the number of bytes unused in the buffer |
| 180 | */ |
| 181 | public final int getRemaining() |
| 182 | { |
| 183 | return bufferSize - nextChar; |
| 184 | } |
| 185 | |
| 186 | /** |
| 187 | * Write a single character. |
| 188 | * |
| 189 | */ |
| 190 | public final void write(int c) throws IOException |
| 191 | { |
| 192 | if (bufferSize == 0) |
| 193 | { |
| 194 | writer.write(c); |
| 195 | } |
| 196 | else |
| 197 | { |
| 198 | if (nextChar >= bufferSize) |
| 199 | if (autoFlush) |
| 200 | flushBuffer(); |
| 201 | else |
| 202 | bufferOverflow(); |
| 203 | cb[nextChar++] = (char) c; |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * Our own little min method, to avoid loading |
| 209 | * <code>java.lang.Math</code> if we've run out of file |
| 210 | * descriptors and we're trying to print a stack trace. |
| 211 | */ |
| 212 | private final int min(int a, int b) |
| 213 | { |
| 214 | return (a < b ? a : b); |
| 215 | } |
| 216 | |
| 217 | /** |
| 218 | * Write a portion of an array of characters. |
| 219 | * |
| 220 | * <p> Ordinarily this method stores characters from the given array into |
| 221 | * this stream's buffer, flushing the buffer to the underlying stream as |
| 222 | * needed. If the requested length is at least as large as the buffer, |
| 223 | * however, then this method will flush the buffer and write the characters |
| 224 | * directly to the underlying stream. Thus redundant |
| 225 | * <code>DiscardableBufferedWriter</code>s will not copy data unnecessarily. |
| 226 | * |
| 227 | * @param cbuf A character array |
| 228 | * @param off Offset from which to start reading characters |
| 229 | * @param len Number of characters to write |
| 230 | * |
| 231 | */ |
| 232 | public final void write(char cbuf[], int off, int len) |
| 233 | throws IOException |
| 234 | { |
| 235 | if (bufferSize == 0) |
| 236 | { |
| 237 | writer.write(cbuf, off, len); |
| 238 | return; |
| 239 | } |
| 240 | |
| 241 | if (len == 0) |
| 242 | { |
| 243 | return; |
| 244 | } |
| 245 | |
| 246 | if (len >= bufferSize) |
| 247 | { |
| 248 | /* If the request length exceeds the size of the output buffer, |
| 249 | flush the buffer and then write the data directly. In this |
| 250 | way buffered streams will cascade harmlessly. */ |
| 251 | if (autoFlush) |
| 252 | flushBuffer(); |
| 253 | else |
| 254 | bufferOverflow(); |
| 255 | writer.write(cbuf, off, len); |
| 256 | return; |
| 257 | } |
| 258 | |
| 259 | int b = off, t = off + len; |
| 260 | while (b < t) |
| 261 | { |
| 262 | int d = min(bufferSize - nextChar, t - b); |
| 263 | System.arraycopy(cbuf, b, cb, nextChar, d); |
| 264 | b += d; |
| 265 | nextChar += d; |
| 266 | if (nextChar >= bufferSize) |
| 267 | if (autoFlush) |
| 268 | flushBuffer(); |
| 269 | else |
| 270 | bufferOverflow(); |
| 271 | } |
| 272 | } |
| 273 | |
| 274 | /** |
| 275 | * Write an array of characters. This method cannot be inherited from the |
| 276 | * Writer class because it must suppress I/O exceptions. |
| 277 | */ |
| 278 | public final void write(char buf[]) throws IOException |
| 279 | { |
| 280 | write(buf, 0, buf.length); |
| 281 | } |
| 282 | |
| 283 | /** |
| 284 | * Write a portion of a String. |
| 285 | * |
| 286 | * @param s String to be written |
| 287 | * @param off Offset from which to start reading characters |
| 288 | * @param len Number of characters to be written |
| 289 | * |
| 290 | */ |
| 291 | public final void write(String s, int off, int len) throws IOException |
| 292 | { |
| 293 | if (bufferSize == 0) |
| 294 | { |
| 295 | writer.write(s, off, len); |
| 296 | return; |
| 297 | } |
| 298 | int b = off, t = off + len; |
| 299 | while (b < t) |
| 300 | { |
| 301 | int d = min(bufferSize - nextChar, t - b); |
| 302 | s.getChars(b, b + d, cb, nextChar); |
| 303 | b += d; |
| 304 | nextChar += d; |
| 305 | if (nextChar >= bufferSize) |
| 306 | if (autoFlush) |
| 307 | flushBuffer(); |
| 308 | else |
| 309 | bufferOverflow(); |
| 310 | } |
| 311 | } |
| 312 | |
| 313 | /** |
| 314 | * Write a string. This method cannot be inherited from the Writer class |
| 315 | * because it must suppress I/O exceptions. |
| 316 | */ |
| 317 | public final void write(String s) throws IOException |
| 318 | { |
| 319 | write(s, 0, s.length()); |
| 320 | } |
| 321 | |
| 322 | /** |
| 323 | * resets this class so that it can be reused |
| 324 | * |
| 325 | */ |
| 326 | public final void recycle( Writer writer) |
| 327 | { |
| 328 | this.writer = writer; |
| 329 | flushed = false; |
| 330 | clear(); |
| 331 | } |
| 332 | } |