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 java.io.EOFException;
 20  
 import java.io.IOException;
 21  
 import java.io.InputStream;
 22  
 
 23  
 /**
 24  
  * A functional, light weight {@link InputStream} that emulates
 25  
  * a stream of a specified size.
 26  
  * <p>
 27  
  * This implementation provides a light weight
 28  
  * object for testing with an {@link InputStream}
 29  
  * where the contents don't matter.
 30  
  * <p>
 31  
  * One use case would be for testing the handling of
 32  
  * large {@link InputStream} as it can emulate that
 33  
  * scenario without the overhead of actually processing
 34  
  * large numbers of bytes - significantly speeding up
 35  
  * test execution times.
 36  
  * <p>
 37  
  * This implementation returns zero from the method that
 38  
  * reads a byte and leaves the array unchanged in the read
 39  
  * methods that are passed a byte array.
 40  
  * If alternative data is required the <code>processByte()</code> and
 41  
  * <code>processBytes()</code> methods can be implemented to generate
 42  
  * data, for example:
 43  
  *
 44  
  * <pre>
 45  
  *  public class TestInputStream extends NullInputStream {
 46  
  *      public TestInputStream(int size) {
 47  
  *          super(size);
 48  
  *      }
 49  
  *      protected int processByte() {
 50  
  *          return ... // return required value here
 51  
  *      }
 52  
  *      protected void processBytes(byte[] bytes, int offset, int length) {
 53  
  *          for (int i = offset; i &lt; length; i++) {
 54  
  *              bytes[i] = ... // set array value here
 55  
  *          }
 56  
  *      }
 57  
  *  }
 58  
  * </pre>
 59  
  *
 60  
  * @since 1.3
 61  
  * @version $Id: NullInputStream.java 1563227 2014-01-31 19:45:30Z ggregory $
 62  
  */
 63  
 public class NullInputStream extends InputStream {
 64  
 
 65  
     private final long size;
 66  
     private long position;
 67  18
     private long mark = -1;
 68  
     private long readlimit;
 69  
     private boolean eof;
 70  
     private final boolean throwEofException;
 71  
     private final boolean markSupported;
 72  
 
 73  
     /**
 74  
      * Create an {@link InputStream} that emulates a specified size
 75  
      * which supports marking and does not throw EOFException.
 76  
      *
 77  
      * @param size The size of the input stream to emulate.
 78  
      */
 79  
     public NullInputStream(final long size) {
 80  10
        this(size, true, false);
 81  10
     }
 82  
 
 83  
     /**
 84  
      * Create an {@link InputStream} that emulates a specified
 85  
      * size with option settings.
 86  
      *
 87  
      * @param size The size of the input stream to emulate.
 88  
      * @param markSupported Whether this instance will support
 89  
      * the <code>mark()</code> functionality.
 90  
      * @param throwEofException Whether this implementation
 91  
      * will throw an {@link EOFException} or return -1 when the
 92  
      * end of file is reached.
 93  
      */
 94  18
     public NullInputStream(final long size, final boolean markSupported, final boolean throwEofException) {
 95  18
        this.size = size;
 96  18
        this.markSupported = markSupported;
 97  18
        this.throwEofException = throwEofException;
 98  18
     }
 99  
 
 100  
     /**
 101  
      * Return the current position.
 102  
      *
 103  
      * @return the current position.
 104  
      */
 105  
     public long getPosition() {
 106  60
         return position;
 107  
     }
 108  
 
 109  
     /**
 110  
      * Return the size this {@link InputStream} emulates.
 111  
      *
 112  
      * @return The size of the input stream to emulate.
 113  
      */
 114  
     public long getSize() {
 115  0
         return size;
 116  
     }
 117  
 
 118  
     /**
 119  
      * Return the number of bytes that can be read.
 120  
      *
 121  
      * @return The number of bytes that can be read.
 122  
      */
 123  
     @Override
 124  
     public int available() {
 125  16
         final long avail = size - position;
 126  16
         if (avail <= 0) {
 127  4
             return 0;
 128  12
         } else if (avail > Integer.MAX_VALUE) {
 129  0
             return Integer.MAX_VALUE;
 130  
         } else {
 131  12
             return (int)avail;
 132  
         }
 133  
     }
 134  
 
 135  
     /**
 136  
      * Close this input stream - resets the internal state to
 137  
      * the initial values.
 138  
      *
 139  
      * @throws IOException If an error occurs.
 140  
      */
 141  
     @Override
 142  
     public void close() throws IOException {
 143  18
         eof = false;
 144  18
         position = 0;
 145  18
         mark = -1;
 146  18
     }
 147  
 
 148  
     /**
 149  
      * Mark the current position.
 150  
      *
 151  
      * @param readlimit The number of bytes before this marked position
 152  
      * is invalid.
 153  
      * @throws UnsupportedOperationException if mark is not supported.
 154  
      */
 155  
     @Override
 156  
     public synchronized void mark(final int readlimit) {
 157  4
         if (!markSupported) {
 158  2
             throw new UnsupportedOperationException("Mark not supported");
 159  
         }
 160  2
         mark = position;
 161  2
         this.readlimit = readlimit;
 162  2
     }
 163  
 
 164  
     /**
 165  
      * Indicates whether <i>mark</i> is supported.
 166  
      *
 167  
      * @return Whether <i>mark</i> is supported or not.
 168  
      */
 169  
     @Override
 170  
     public boolean markSupported() {
 171  4
         return markSupported;
 172  
     }
 173  
 
 174  
     /**
 175  
      * Read a byte.
 176  
      *
 177  
      * @return Either The byte value returned by <code>processByte()</code>
 178  
      * or <code>-1</code> if the end of file has been reached and
 179  
      * <code>throwEofException</code> is set to {@code false}.
 180  
      * @throws EOFException if the end of file is reached and
 181  
      * <code>throwEofException</code> is set to {@code true}.
 182  
      * @throws IOException if trying to read past the end of file.
 183  
      */
 184  
     @Override
 185  
     public int read() throws IOException {
 186  60
         if (eof) {
 187  2
             throw new IOException("Read after end of file");
 188  
         }
 189  58
         if (position == size) {
 190  4
             return doEndOfFile();
 191  
         }
 192  54
         position++;
 193  54
         return processByte();
 194  
     }
 195  
 
 196  
     /**
 197  
      * Read some bytes into the specified array.
 198  
      *
 199  
      * @param bytes The byte array to read into
 200  
      * @return The number of bytes read or <code>-1</code>
 201  
      * if the end of file has been reached and
 202  
      * <code>throwEofException</code> is set to {@code false}.
 203  
      * @throws EOFException if the end of file is reached and
 204  
      * <code>throwEofException</code> is set to {@code true}.
 205  
      * @throws IOException if trying to read past the end of file.
 206  
      */
 207  
     @Override
 208  
     public int read(final byte[] bytes) throws IOException {
 209  6291476
         return read(bytes, 0, bytes.length);
 210  
     }
 211  
 
 212  
     /**
 213  
      * Read the specified number bytes into an array.
 214  
      *
 215  
      * @param bytes The byte array to read into.
 216  
      * @param offset The offset to start reading bytes into.
 217  
      * @param length The number of bytes to read.
 218  
      * @return The number of bytes read or <code>-1</code>
 219  
      * if the end of file has been reached and
 220  
      * <code>throwEofException</code> is set to {@code false}.
 221  
      * @throws EOFException if the end of file is reached and
 222  
      * <code>throwEofException</code> is set to {@code true}.
 223  
      * @throws IOException if trying to read past the end of file.
 224  
      */
 225  
     @Override
 226  
     public int read(final byte[] bytes, final int offset, final int length) throws IOException {
 227  6291478
         if (eof) {
 228  2
             throw new IOException("Read after end of file");
 229  
         }
 230  6291476
         if (position == size) {
 231  14
             return doEndOfFile();
 232  
         }
 233  6291462
         position += length;
 234  6291462
         int returnLength = length;
 235  6291462
         if (position > size) {
 236  2
             returnLength = length - (int)(position - size);
 237  2
             position = size;
 238  
         }
 239  6291462
         processBytes(bytes, offset, returnLength);
 240  6291462
         return returnLength;
 241  
     }
 242  
 
 243  
     /**
 244  
      * Reset the stream to the point when mark was last called.
 245  
      *
 246  
      * @throws UnsupportedOperationException if mark is not supported.
 247  
      * @throws IOException If no position has been marked
 248  
      * or the read limit has been exceed since the last position was
 249  
      * marked.
 250  
      */
 251  
     @Override
 252  
     public synchronized void reset() throws IOException {
 253  8
         if (!markSupported) {
 254  2
             throw new UnsupportedOperationException("Mark not supported");
 255  
         }
 256  6
         if (mark < 0) {
 257  2
             throw new IOException("No position has been marked");
 258  
         }
 259  4
         if (position > mark + readlimit) {
 260  2
             throw new IOException("Marked position [" + mark +
 261  
                     "] is no longer valid - passed the read limit [" +
 262  
                     readlimit + "]");
 263  
         }
 264  2
         position = mark;
 265  2
         eof = false;
 266  2
     }
 267  
 
 268  
     /**
 269  
      * Skip a specified number of bytes.
 270  
      *
 271  
      * @param numberOfBytes The number of bytes to skip.
 272  
      * @return The number of bytes skipped or <code>-1</code>
 273  
      * if the end of file has been reached and
 274  
      * <code>throwEofException</code> is set to {@code false}.
 275  
      * @throws EOFException if the end of file is reached and
 276  
      * <code>throwEofException</code> is set to {@code true}.
 277  
      * @throws IOException if trying to read past the end of file.
 278  
      */
 279  
     @Override
 280  
     public long skip(final long numberOfBytes) throws IOException {
 281  8
         if (eof) {
 282  2
             throw new IOException("Skip after end of file");
 283  
         }
 284  6
         if (position == size) {
 285  2
             return doEndOfFile();
 286  
         }
 287  4
         position += numberOfBytes;
 288  4
         long returnLength = numberOfBytes;
 289  4
         if (position > size) {
 290  2
             returnLength = numberOfBytes - (position - size);
 291  2
             position = size;
 292  
         }
 293  4
         return returnLength;
 294  
     }
 295  
 
 296  
     /**
 297  
      * Return a byte value for the  <code>read()</code> method.
 298  
      * <p>
 299  
      * This implementation returns zero.
 300  
      *
 301  
      * @return This implementation always returns zero.
 302  
      */
 303  
     protected int processByte() {
 304  
         // do nothing - overridable by subclass
 305  0
         return 0;
 306  
     }
 307  
 
 308  
     /**
 309  
      * Process the bytes for the <code>read(byte[], offset, length)</code>
 310  
      * method.
 311  
      * <p>
 312  
      * This implementation leaves the byte array unchanged.
 313  
      *
 314  
      * @param bytes The byte array
 315  
      * @param offset The offset to start at.
 316  
      * @param length The number of bytes.
 317  
      */
 318  
     protected void processBytes(final byte[] bytes, final int offset, final int length) {
 319  
         // do nothing - overridable by subclass
 320  6291456
     }
 321  
 
 322  
     /**
 323  
      * Handle End of File.
 324  
      *
 325  
      * @return <code>-1</code> if <code>throwEofException</code> is
 326  
      * set to {@code false}
 327  
      * @throws EOFException if <code>throwEofException</code> is set
 328  
      * to {@code true}.
 329  
      */
 330  
     private int doEndOfFile() throws EOFException {
 331  20
         eof = true;
 332  20
         if (throwEofException) {
 333  2
             throw new EOFException();
 334  
         }
 335  18
         return -1;
 336  
     }
 337  
 
 338  
 }