Coverage Report - org.apache.commons.io.input.NullInputStream
 
Classes in this File Line Coverage Branch Coverage Complexity
NullInputStream
95%
66/69
96%
29/30
2.75
 
 1  
 /*
 2  
  * Licensed to the Apache Software Foundation (ASF) under one or more
 3  
  * contributor license agreements.  See the NOTICE file distributed with
 4  
  * this work for additional information regarding copyright ownership.
 5  
  * The ASF licenses this file to You under the Apache License, Version 2.0
 6  
  * (the "License"); you may not use this file except in compliance with
 7  
  * the License.  You may obtain a copy of the License at
 8  
  * 
 9  
  *      http://www.apache.org/licenses/LICENSE-2.0
 10  
  * 
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 package org.apache.commons.io.input;
 18  
 
 19  
 import static org.apache.commons.io.IOUtils.EOF;
 20  
 
 21  
 import java.io.EOFException;
 22  
 import java.io.IOException;
 23  
 import java.io.InputStream;
 24  
 
 25  
 /**
 26  
  * A functional, light weight {@link InputStream} that emulates
 27  
  * a stream of a specified size.
 28  
  * <p>
 29  
  * This implementation provides a light weight
 30  
  * object for testing with an {@link InputStream}
 31  
  * where the contents don't matter.
 32  
  * <p>
 33  
  * One use case would be for testing the handling of
 34  
  * large {@link InputStream} as it can emulate that
 35  
  * scenario without the overhead of actually processing
 36  
  * large numbers of bytes - significantly speeding up
 37  
  * test execution times.
 38  
  * <p>
 39  
  * This implementation returns zero from the method that
 40  
  * reads a byte and leaves the array unchanged in the read
 41  
  * methods that are passed a byte array.
 42  
  * If alternative data is required the <code>processByte()</code> and
 43  
  * <code>processBytes()</code> methods can be implemented to generate
 44  
  * data, for example:
 45  
  *
 46  
  * <pre>
 47  
  *  public class TestInputStream extends NullInputStream {
 48  
  *      public TestInputStream(int size) {
 49  
  *          super(size);
 50  
  *      }
 51  
  *      protected int processByte() {
 52  
  *          return ... // return required value here
 53  
  *      }
 54  
  *      protected void processBytes(byte[] bytes, int offset, int length) {
 55  
  *          for (int i = offset; i &lt; length; i++) {
 56  
  *              bytes[i] = ... // set array value here
 57  
  *          }
 58  
  *      }
 59  
  *  }
 60  
  * </pre>
 61  
  *
 62  
  * @since 1.3
 63  
  * @version $Id: NullInputStream.java 1586350 2014-04-10 15:57:20Z ggregory $
 64  
  */
 65  
 public class NullInputStream extends InputStream {
 66  
 
 67  
     private final long size;
 68  
     private long position;
 69  9
     private long mark = -1;
 70  
     private long readlimit;
 71  
     private boolean eof;
 72  
     private final boolean throwEofException;
 73  
     private final boolean markSupported;
 74  
 
 75  
     /**
 76  
      * Create an {@link InputStream} that emulates a specified size
 77  
      * which supports marking and does not throw EOFException.
 78  
      *
 79  
      * @param size The size of the input stream to emulate.
 80  
      */
 81  
     public NullInputStream(final long size) {
 82  5
        this(size, true, false);
 83  5
     }
 84  
 
 85  
     /**
 86  
      * Create an {@link InputStream} that emulates a specified
 87  
      * size with option settings.
 88  
      *
 89  
      * @param size The size of the input stream to emulate.
 90  
      * @param markSupported Whether this instance will support
 91  
      * the <code>mark()</code> functionality.
 92  
      * @param throwEofException Whether this implementation
 93  
      * will throw an {@link EOFException} or return -1 when the
 94  
      * end of file is reached.
 95  
      */
 96  9
     public NullInputStream(final long size, final boolean markSupported, final boolean throwEofException) {
 97  9
        this.size = size;
 98  9
        this.markSupported = markSupported;
 99  9
        this.throwEofException = throwEofException;
 100  9
     }
 101  
 
 102  
     /**
 103  
      * Return the current position.
 104  
      *
 105  
      * @return the current position.
 106  
      */
 107  
     public long getPosition() {
 108  30
         return position;
 109  
     }
 110  
 
 111  
     /**
 112  
      * Return the size this {@link InputStream} emulates.
 113  
      *
 114  
      * @return The size of the input stream to emulate.
 115  
      */
 116  
     public long getSize() {
 117  0
         return size;
 118  
     }
 119  
 
 120  
     /**
 121  
      * Return the number of bytes that can be read.
 122  
      *
 123  
      * @return The number of bytes that can be read.
 124  
      */
 125  
     @Override
 126  
     public int available() {
 127  8
         final long avail = size - position;
 128  8
         if (avail <= 0) {
 129  2
             return 0;
 130  6
         } else if (avail > Integer.MAX_VALUE) {
 131  0
             return Integer.MAX_VALUE;
 132  
         } else {
 133  6
             return (int)avail;
 134  
         }
 135  
     }
 136  
 
 137  
     /**
 138  
      * Close this input stream - resets the internal state to
 139  
      * the initial values.
 140  
      *
 141  
      * @throws IOException If an error occurs.
 142  
      */
 143  
     @Override
 144  
     public void close() throws IOException {
 145  9
         eof = false;
 146  9
         position = 0;
 147  9
         mark = -1;
 148  9
     }
 149  
 
 150  
     /**
 151  
      * Mark the current position.
 152  
      *
 153  
      * @param readlimit The number of bytes before this marked position
 154  
      * is invalid.
 155  
      * @throws UnsupportedOperationException if mark is not supported.
 156  
      */
 157  
     @Override
 158  
     public synchronized void mark(final int readlimit) {
 159  2
         if (!markSupported) {
 160  1
             throw new UnsupportedOperationException("Mark not supported");
 161  
         }
 162  1
         mark = position;
 163  1
         this.readlimit = readlimit;
 164  1
     }
 165  
 
 166  
     /**
 167  
      * Indicates whether <i>mark</i> is supported.
 168  
      *
 169  
      * @return Whether <i>mark</i> is supported or not.
 170  
      */
 171  
     @Override
 172  
     public boolean markSupported() {
 173  2
         return markSupported;
 174  
     }
 175  
 
 176  
     /**
 177  
      * Read a byte.
 178  
      *
 179  
      * @return Either The byte value returned by <code>processByte()</code>
 180  
      * or <code>-1</code> if the end of file has been reached and
 181  
      * <code>throwEofException</code> is set to {@code false}.
 182  
      * @throws EOFException if the end of file is reached and
 183  
      * <code>throwEofException</code> is set to {@code true}.
 184  
      * @throws IOException if trying to read past the end of file.
 185  
      */
 186  
     @Override
 187  
     public int read() throws IOException {
 188  30
         if (eof) {
 189  1
             throw new IOException("Read after end of file");
 190  
         }
 191  29
         if (position == size) {
 192  2
             return doEndOfFile();
 193  
         }
 194  27
         position++;
 195  27
         return processByte();
 196  
     }
 197  
 
 198  
     /**
 199  
      * Read some bytes into the specified array.
 200  
      *
 201  
      * @param bytes The byte array to read into
 202  
      * @return The number of bytes read or <code>-1</code>
 203  
      * if the end of file has been reached and
 204  
      * <code>throwEofException</code> is set to {@code false}.
 205  
      * @throws EOFException if the end of file is reached and
 206  
      * <code>throwEofException</code> is set to {@code true}.
 207  
      * @throws IOException if trying to read past the end of file.
 208  
      */
 209  
     @Override
 210  
     public int read(final byte[] bytes) throws IOException {
 211  3145738
         return read(bytes, 0, bytes.length);
 212  
     }
 213  
 
 214  
     /**
 215  
      * Read the specified number bytes into an array.
 216  
      *
 217  
      * @param bytes The byte array to read into.
 218  
      * @param offset The offset to start reading bytes into.
 219  
      * @param length The number of bytes to read.
 220  
      * @return The number of bytes read or <code>-1</code>
 221  
      * if the end of file has been reached and
 222  
      * <code>throwEofException</code> is set to {@code false}.
 223  
      * @throws EOFException if the end of file is reached and
 224  
      * <code>throwEofException</code> is set to {@code true}.
 225  
      * @throws IOException if trying to read past the end of file.
 226  
      */
 227  
     @Override
 228  
     public int read(final byte[] bytes, final int offset, final int length) throws IOException {
 229  3145739
         if (eof) {
 230  1
             throw new IOException("Read after end of file");
 231  
         }
 232  3145738
         if (position == size) {
 233  7
             return doEndOfFile();
 234  
         }
 235  3145731
         position += length;
 236  3145731
         int returnLength = length;
 237  3145731
         if (position > size) {
 238  1
             returnLength = length - (int)(position - size);
 239  1
             position = size;
 240  
         }
 241  3145731
         processBytes(bytes, offset, returnLength);
 242  3145731
         return returnLength;
 243  
     }
 244  
 
 245  
     /**
 246  
      * Reset the stream to the point when mark was last called.
 247  
      *
 248  
      * @throws UnsupportedOperationException if mark is not supported.
 249  
      * @throws IOException If no position has been marked
 250  
      * or the read limit has been exceed since the last position was
 251  
      * marked.
 252  
      */
 253  
     @Override
 254  
     public synchronized void reset() throws IOException {
 255  4
         if (!markSupported) {
 256  1
             throw new UnsupportedOperationException("Mark not supported");
 257  
         }
 258  3
         if (mark < 0) {
 259  1
             throw new IOException("No position has been marked");
 260  
         }
 261  2
         if (position > mark + readlimit) {
 262  1
             throw new IOException("Marked position [" + mark +
 263  
                     "] is no longer valid - passed the read limit [" +
 264  
                     readlimit + "]");
 265  
         }
 266  1
         position = mark;
 267  1
         eof = false;
 268  1
     }
 269  
 
 270  
     /**
 271  
      * Skip a specified number of bytes.
 272  
      *
 273  
      * @param numberOfBytes The number of bytes to skip.
 274  
      * @return The number of bytes skipped or <code>-1</code>
 275  
      * if the end of file has been reached and
 276  
      * <code>throwEofException</code> is set to {@code false}.
 277  
      * @throws EOFException if the end of file is reached and
 278  
      * <code>throwEofException</code> is set to {@code true}.
 279  
      * @throws IOException if trying to read past the end of file.
 280  
      */
 281  
     @Override
 282  
     public long skip(final long numberOfBytes) throws IOException {
 283  4
         if (eof) {
 284  1
             throw new IOException("Skip after end of file");
 285  
         }
 286  3
         if (position == size) {
 287  1
             return doEndOfFile();
 288  
         }
 289  2
         position += numberOfBytes;
 290  2
         long returnLength = numberOfBytes;
 291  2
         if (position > size) {
 292  1
             returnLength = numberOfBytes - (position - size);
 293  1
             position = size;
 294  
         }
 295  2
         return returnLength;
 296  
     }
 297  
 
 298  
     /**
 299  
      * Return a byte value for the  <code>read()</code> method.
 300  
      * <p>
 301  
      * This implementation returns zero.
 302  
      *
 303  
      * @return This implementation always returns zero.
 304  
      */
 305  
     protected int processByte() {
 306  
         // do nothing - overridable by subclass
 307  0
         return 0;
 308  
     }
 309  
 
 310  
     /**
 311  
      * Process the bytes for the <code>read(byte[], offset, length)</code>
 312  
      * method.
 313  
      * <p>
 314  
      * This implementation leaves the byte array unchanged.
 315  
      *
 316  
      * @param bytes The byte array
 317  
      * @param offset The offset to start at.
 318  
      * @param length The number of bytes.
 319  
      */
 320  
     protected void processBytes(final byte[] bytes, final int offset, final int length) {
 321  
         // do nothing - overridable by subclass
 322  3145728
     }
 323  
 
 324  
     /**
 325  
      * Handle End of File.
 326  
      *
 327  
      * @return <code>-1</code> if <code>throwEofException</code> is
 328  
      * set to {@code false}
 329  
      * @throws EOFException if <code>throwEofException</code> is set
 330  
      * to {@code true}.
 331  
      */
 332  
     private int doEndOfFile() throws EOFException {
 333  10
         eof = true;
 334  10
         if (throwEofException) {
 335  1
             throw new EOFException();
 336  
         }
 337  9
         return EOF;
 338  
     }
 339  
 
 340  
 }