1 /**
2 *
3 * Copyright 2003-2004 The Apache Software Foundation
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * 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
18
19
20
21
22
23
24 package javax.servlet;
25
26 import java.io.IOException;
27 import java.io.InputStream;
28
29 /**
30 *
31 * Provides an input stream for reading binary data from a client
32 * request, including an efficient <code>readLine</code> method
33 * for reading data one line at a time. With some protocols, such
34 * as HTTP POST and PUT, a <code>ServletInputStream</code>
35 * object can be used to read data sent from the client.
36 *
37 * <p>A <code>ServletInputStream</code> object is normally retrieved via
38 * the {@link ServletRequest#getInputStream} method.
39 *
40 * <p>This is an abstract class that a servlet container implements.
41 * Subclasses of this class
42 * must implement the <code>java.io.InputStream.read()</code> method.
43 *
44 * @see ServletRequest
45 *
46 * @version $Rev: 46019 $ $Date: 2004-09-14 02:56:06 -0700 (Tue, 14 Sep 2004) $
47 */
48 public abstract class ServletInputStream extends InputStream {
49 /**
50 * Does nothing, because this is an abstract class.
51 */
52 protected ServletInputStream() {
53 }
54
55 /**
56 * Reads the input stream, one line at a time. Starting at an
57 * offset, reads bytes into an array, until it reads a certain number
58 * of bytes or reaches a newline character, which it reads into the
59 * array as well.
60 *
61 * <p>This method returns -1 if it reaches the end of the input
62 * stream before reading the maximum number of bytes.
63 *
64 * @param b an array of bytes into which data is read
65 *
66 * @param off an integer specifying the character at which
67 * this method begins reading
68 *
69 * @param len an integer specifying the maximum number of
70 * bytes to read
71 *
72 * @return an integer specifying the actual number of bytes
73 * read, or -1 if the end of the stream is reached
74 *
75 * @exception IOException if an input or output exception has occurred
76 */
77 public int readLine(byte[] b, int off, int len) throws IOException {
78 if (len <= 0) {
79 return 0;
80 }
81 int count = 0, c;
82
83 while ((c = read()) != -1) {
84 b[off++] = (byte) c;
85 count++;
86 if (c == '\n' || count == len) {
87 break;
88 }
89 }
90 return count > 0 ? count : -1;
91 }
92 }
93
94
95