001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *  http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    
020    //
021    // This source code implements specifications defined by the Java
022    // Community Process. In order to remain compliant with the specification
023    // DO NOT add / change / or delete method signatures!
024    //
025    
026    package javax.servlet;
027    
028    import java.io.IOException;
029    import java.io.InputStream;
030    
031    /**
032     *
033     * Provides an input stream for reading binary data from a client
034     * request, including an efficient <code>readLine</code> method
035     * for reading data one line at a time. With some protocols, such
036     * as HTTP POST and PUT, a <code>ServletInputStream</code>
037     * object can be used to read data sent from the client.
038     *
039     * <p>A <code>ServletInputStream</code> object is normally retrieved via
040     * the {@link ServletRequest#getInputStream} method.
041     *
042     * <p>This is an abstract class that a servlet container implements.
043     * Subclasses of this class
044     * must implement the <code>java.io.InputStream.read()</code> method.
045     *
046     * @see ServletRequest
047     *
048     * @version $Rev: 467553 $ $Date: 2006-10-24 21:01:51 -0700 (Tue, 24 Oct 2006) $
049     */
050    public abstract class ServletInputStream extends InputStream {
051        /**
052         * Does nothing, because this is an abstract class.
053         */
054        protected ServletInputStream() {
055        }
056    
057        /**
058         * Reads the input stream, one line at a time. Starting at an
059         * offset, reads bytes into an array, until it reads a certain number
060         * of bytes or reaches a newline character, which it reads into the
061         * array as well.
062         *
063         * <p>This method returns -1 if it reaches the end of the input
064         * stream before reading the maximum number of bytes.
065         *
066         * @param b an array of bytes into which data is read
067         *
068         * @param off an integer specifying the character at which
069         * this method begins reading
070         *
071         * @param len an integer specifying the maximum number of
072         * bytes to read
073         *
074         * @return an integer specifying the actual number of bytes
075         * read, or -1 if the end of the stream is reached
076         *
077         * @exception IOException if an input or output exception has occurred
078         */
079        public int readLine(byte[] b, int off, int len) throws IOException {
080            if (len <= 0) {
081                return 0;
082            }
083            int count = 0, c;
084    
085            while ((c = read()) != -1) {
086                b[off++] = (byte) c;
087                count++;
088                if (c == '\n' || count == len) {
089                    break;
090                }
091            }
092            return count > 0 ? count : -1;
093        }
094    }
095    
096    
097