Coverage Report - org.apache.commons.io.output.ThresholdingOutputStream
 
Classes in this File Line Coverage Branch Coverage Complexity
ThresholdingOutputStream
68%
22/32
100%
6/6
1.231
 
 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.output;
 18  
 
 19  
 import java.io.IOException;
 20  
 import java.io.OutputStream;
 21  
 
 22  
 
 23  
 /**
 24  
  * An output stream which triggers an event when a specified number of bytes of
 25  
  * data have been written to it. The event can be used, for example, to throw
 26  
  * an exception if a maximum has been reached, or to switch the underlying
 27  
  * stream type when the threshold is exceeded.
 28  
  * <p>
 29  
  * This class overrides all <code>OutputStream</code> methods. However, these
 30  
  * overrides ultimately call the corresponding methods in the underlying output
 31  
  * stream implementation.
 32  
  * <p>
 33  
  * NOTE: This implementation may trigger the event <em>before</em> the threshold
 34  
  * is actually reached, since it triggers when a pending write operation would
 35  
  * cause the threshold to be exceeded.
 36  
  *
 37  
  * @version $Id: ThresholdingOutputStream.java 1415850 2012-11-30 20:51:39Z ggregory $
 38  
  */
 39  
 public abstract class ThresholdingOutputStream
 40  
     extends OutputStream
 41  
 {
 42  
 
 43  
     // ----------------------------------------------------------- Data members
 44  
 
 45  
 
 46  
     /**
 47  
      * The threshold at which the event will be triggered.
 48  
      */
 49  
     private final int threshold;
 50  
 
 51  
 
 52  
     /**
 53  
      * The number of bytes written to the output stream.
 54  
      */
 55  
     private long written;
 56  
 
 57  
 
 58  
     /**
 59  
      * Whether or not the configured threshold has been exceeded.
 60  
      */
 61  
     private boolean thresholdExceeded;
 62  
 
 63  
 
 64  
     // ----------------------------------------------------------- Constructors
 65  
 
 66  
 
 67  
     /**
 68  
      * Constructs an instance of this class which will trigger an event at the
 69  
      * specified threshold.
 70  
      *
 71  
      * @param threshold The number of bytes at which to trigger an event.
 72  
      */
 73  
     public ThresholdingOutputStream(final int threshold)
 74  20
     {
 75  20
         this.threshold = threshold;
 76  20
     }
 77  
 
 78  
 
 79  
     // --------------------------------------------------- OutputStream methods
 80  
 
 81  
 
 82  
     /**
 83  
      * Writes the specified byte to this output stream.
 84  
      *
 85  
      * @param b The byte to be written.
 86  
      *
 87  
      * @exception IOException if an error occurs.
 88  
      */
 89  
     @Override
 90  
     public void write(final int b) throws IOException
 91  
     {
 92  0
         checkThreshold(1);
 93  0
         getStream().write(b);
 94  0
         written++;
 95  0
     }
 96  
 
 97  
 
 98  
     /**
 99  
      * Writes <code>b.length</code> bytes from the specified byte array to this
 100  
      * output stream.
 101  
      *
 102  
      * @param b The array of bytes to be written.
 103  
      *
 104  
      * @exception IOException if an error occurs.
 105  
      */
 106  
     @Override
 107  
     public void write(final byte b[]) throws IOException
 108  
     {
 109  4
         checkThreshold(b.length);
 110  4
         getStream().write(b);
 111  4
         written += b.length;
 112  4
     }
 113  
 
 114  
 
 115  
     /**
 116  
      * Writes <code>len</code> bytes from the specified byte array starting at
 117  
      * offset <code>off</code> to this output stream.
 118  
      *
 119  
      * @param b   The byte array from which the data will be written.
 120  
      * @param off The start offset in the byte array.
 121  
      * @param len The number of bytes to write.
 122  
      *
 123  
      * @exception IOException if an error occurs.
 124  
      */
 125  
     @Override
 126  
     public void write(final byte b[], final int off, final int len) throws IOException
 127  
     {
 128  18
         checkThreshold(len);
 129  18
         getStream().write(b, off, len);
 130  18
         written += len;
 131  18
     }
 132  
 
 133  
 
 134  
     /**
 135  
      * Flushes this output stream and forces any buffered output bytes to be
 136  
      * written out.
 137  
      *
 138  
      * @exception IOException if an error occurs.
 139  
      */
 140  
     @Override
 141  
     public void flush() throws IOException
 142  
     {
 143  18
         getStream().flush();
 144  18
     }
 145  
 
 146  
 
 147  
     /**
 148  
      * Closes this output stream and releases any system resources associated
 149  
      * with this stream.
 150  
      *
 151  
      * @exception IOException if an error occurs.
 152  
      */
 153  
     @Override
 154  
     public void close() throws IOException
 155  
     {
 156  
         try
 157  
         {
 158  18
             flush();
 159  
         }
 160  0
         catch (final IOException ignored)
 161  
         {
 162  
             // ignore
 163  18
         }
 164  18
         getStream().close();
 165  18
     }
 166  
 
 167  
 
 168  
     // --------------------------------------------------------- Public methods
 169  
 
 170  
 
 171  
     /**
 172  
      * Returns the threshold, in bytes, at which an event will be triggered.
 173  
      *
 174  
      * @return The threshold point, in bytes.
 175  
      */
 176  
     public int getThreshold()
 177  
     {
 178  0
         return threshold;
 179  
     }
 180  
 
 181  
 
 182  
     /**
 183  
      * Returns the number of bytes that have been written to this output stream.
 184  
      *
 185  
      * @return The number of bytes written.
 186  
      */
 187  
     public long getByteCount()
 188  
     {
 189  0
         return written;
 190  
     }
 191  
 
 192  
 
 193  
     /**
 194  
      * Determines whether or not the configured threshold has been exceeded for
 195  
      * this output stream.
 196  
      *
 197  
      * @return {@code true} if the threshold has been reached;
 198  
      *         {@code false} otherwise.
 199  
      */
 200  
     public boolean isThresholdExceeded()
 201  
     {
 202  22
         return written > threshold;
 203  
     }
 204  
 
 205  
 
 206  
     // ------------------------------------------------------ Protected methods
 207  
 
 208  
 
 209  
     /**
 210  
      * Checks to see if writing the specified number of bytes would cause the
 211  
      * configured threshold to be exceeded. If so, triggers an event to allow
 212  
      * a concrete implementation to take action on this.
 213  
      *
 214  
      * @param count The number of bytes about to be written to the underlying
 215  
      *              output stream.
 216  
      *
 217  
      * @exception IOException if an error occurs.
 218  
      */
 219  
     protected void checkThreshold(final int count) throws IOException
 220  
     {
 221  22
         if (!thresholdExceeded && written + count > threshold)
 222  
         {
 223  10
             thresholdExceeded = true;
 224  10
             thresholdReached();
 225  
         }
 226  22
     }
 227  
 
 228  
     /**
 229  
      * Resets the byteCount to zero.  You can call this from 
 230  
      * {@link #thresholdReached()} if you want the event to be triggered again. 
 231  
      */
 232  
     protected void resetByteCount() 
 233  
     {
 234  0
         this.thresholdExceeded = false;
 235  0
         this.written = 0;
 236  0
     }
 237  
 
 238  
     // ------------------------------------------------------- Abstract methods
 239  
 
 240  
 
 241  
     /**
 242  
      * Returns the underlying output stream, to which the corresponding
 243  
      * <code>OutputStream</code> methods in this class will ultimately delegate.
 244  
      *
 245  
      * @return The underlying output stream.
 246  
      *
 247  
      * @exception IOException if an error occurs.
 248  
      */
 249  
     protected abstract OutputStream getStream() throws IOException;
 250  
 
 251  
 
 252  
     /**
 253  
      * Indicates that the configured threshold has been reached, and that a
 254  
      * subclass should take whatever action necessary on this event. This may
 255  
      * include changing the underlying output stream.
 256  
      *
 257  
      * @exception IOException if an error occurs.
 258  
      */
 259  
     protected abstract void thresholdReached() throws IOException;
 260  
 }