001    /**
002     *
003     * Copyright 2003-2004 The Apache Software Foundation
004     *
005     *  Licensed under the Apache License, Version 2.0 (the "License");
006     *  you may not use this file except in compliance with the License.
007     *  You may obtain a copy of the License at
008     *
009     *     http://www.apache.org/licenses/LICENSE-2.0
010     *
011     *  Unless required by applicable law or agreed to in writing, software
012     *  distributed under the License is distributed on an "AS IS" BASIS,
013     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     *  See the License for the specific language governing permissions and
015     *  limitations under the License.
016     */
017    
018    //
019    // This source code implements specifications defined by the Java
020    // Community Process. In order to remain compliant with the specification
021    // DO NOT add / change / or delete method signatures!
022    //
023    
024    package javax.servlet;
025    
026    import java.io.IOException;
027    import java.io.InputStream;
028    
029    /**
030     *
031     * Provides an input stream for reading binary data from a client
032     * request, including an efficient <code>readLine</code> method
033     * for reading data one line at a time. With some protocols, such
034     * as HTTP POST and PUT, a <code>ServletInputStream</code>
035     * object can be used to read data sent from the client.
036     *
037     * <p>A <code>ServletInputStream</code> object is normally retrieved via
038     * the {@link ServletRequest#getInputStream} method.
039     *
040     * <p>This is an abstract class that a servlet container implements.
041     * Subclasses of this class
042     * must implement the <code>java.io.InputStream.read()</code> method.
043     *
044     * @see ServletRequest
045     *
046     * @version $Rev: 46019 $ $Date: 2004-09-14 02:56:06 -0700 (Tue, 14 Sep 2004) $
047     */
048    public abstract class ServletInputStream extends InputStream {
049        /**
050         * Does nothing, because this is an abstract class.
051         */
052        protected ServletInputStream() {
053        }
054    
055        /**
056         * Reads the input stream, one line at a time. Starting at an
057         * offset, reads bytes into an array, until it reads a certain number
058         * of bytes or reaches a newline character, which it reads into the
059         * array as well.
060         *
061         * <p>This method returns -1 if it reaches the end of the input
062         * stream before reading the maximum number of bytes.
063         *
064         * @param b an array of bytes into which data is read
065         *
066         * @param off an integer specifying the character at which
067         * this method begins reading
068         *
069         * @param len an integer specifying the maximum number of
070         * bytes to read
071         *
072         * @return an integer specifying the actual number of bytes
073         * read, or -1 if the end of the stream is reached
074         *
075         * @exception IOException if an input or output exception has occurred
076         */
077        public int readLine(byte[] b, int off, int len) throws IOException {
078            if (len <= 0) {
079                return 0;
080            }
081            int count = 0, c;
082    
083            while ((c = read()) != -1) {
084                b[off++] = (byte) c;
085                count++;
086                if (c == '\n' || count == len) {
087                    break;
088                }
089            }
090            return count > 0 ? count : -1;
091        }
092    }
093    
094    
095