1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.mina.example.imagine.step1.server;
21
22 import org.apache.mina.core.service.IoHandlerAdapter;
23 import org.apache.mina.core.session.IoSession;
24 import org.apache.mina.example.imagine.step1.ImageRequest;
25 import org.apache.mina.example.imagine.step1.ImageResponse;
26 import org.slf4j.Logger;
27 import org.slf4j.LoggerFactory;
28
29 import java.awt.Color;
30 import java.awt.Font;
31 import java.awt.Graphics;
32 import java.awt.image.BufferedImage;
33
34 /**
35 * server-side {@link org.apache.mina.core.service.IoHandler}
36 *
37 * @author The Apache MINA Project (dev@mina.apache.org)
38 * @version $Rev$, $Date$
39 */
40
41 public class ImageServerIoHandler extends IoHandlerAdapter {
42
43 private final static String characters = "mina rocks abcdefghijklmnopqrstuvwxyz0123456789";
44
45 public static final String INDEX_KEY = ImageServerIoHandler.class.getName() + ".INDEX";
46
47 private Logger logger = LoggerFactory.getLogger(this.getClass());
48
49 /**
50 * Called when the session is opened, which will come after the session created.
51 *
52 * @see org.apache.mina.core.service.IoHandlerAdapter#sessionOpened(org.apache.mina.core.session.IoSession)
53 */
54 public void sessionOpened(IoSession session) throws Exception {
55 session.setAttribute(INDEX_KEY, 0);
56 }
57
58 /**
59 * This method will be called whenever an exception occurs. For this handler,
60 * the logger will generate a warning message.
61 *
62 * @see org.apache.mina.core.service.IoHandlerAdapter#exceptionCaught(org.apache.mina.core.session.IoSession, java.lang.Throwable)
63 */
64 public void exceptionCaught(IoSession session, Throwable cause) throws Exception {
65 logger.warn(cause.getMessage(), cause);
66 }
67
68 /**
69 * Handle incoming messages.
70 *
71 * @see org.apache.mina.core.service.IoHandlerAdapter#messageReceived(org.apache.mina.core.session.IoSession, java.lang.Object)
72 */
73 public void messageReceived(IoSession session, Object message) throws Exception {
74 ImageRequest request = (ImageRequest) message;
75 String text1 = generateString(session, request.getNumberOfCharacters());
76 String text2 = generateString(session, request.getNumberOfCharacters());
77 BufferedImage image1 = createImage(request, text1);
78 BufferedImage image2 = createImage(request, text2);
79 ImageResponse response = new ImageResponse(image1, image2);
80 session.write(response);
81 }
82
83 /**
84 * Create an image using the specified request and the text.
85 *
86 * @param request
87 * Determines the height and width of the image
88 * @param text
89 * The text that is placed in the image
90 * @return
91 * a BufferedImage representing the text.
92 */
93 private BufferedImage createImage(ImageRequest request, String text) {
94 BufferedImage image = new BufferedImage(request.getWidth(), request.getHeight(), BufferedImage.TYPE_BYTE_INDEXED);
95 Graphics graphics = image.createGraphics();
96 graphics.setColor(Color.YELLOW);
97 graphics.fillRect(0, 0, image.getWidth(), image.getHeight());
98 Font serif = new Font("serif", Font.PLAIN, 30);
99 graphics.setFont(serif);
100 graphics.setColor(Color.BLUE);
101 graphics.drawString(text, 10, 50);
102 return image;
103 }
104
105 /**
106 * Generate a string based on the 'characters' field in this class. The
107 * characters that make up the string are based on the session
108 * attribute "INDEX_KEY"
109 *
110 * @param session
111 * The {@link IoSession} object that will provide the INDEX_KEY attribute
112 * @param length
113 * The length that the String will be
114 * @return
115 * The generated String
116 */
117 private String generateString(IoSession session, int length) {
118 Integer index = (Integer) session.getAttribute(INDEX_KEY);
119 StringBuffer buffer = new StringBuffer(length);
120 while (buffer.length() < length) {
121 buffer.append(characters.charAt(index));
122 index++;
123 if (index >= characters.length()) {
124 index = 0;
125 }
126 }
127 session.setAttribute(INDEX_KEY, index);
128 return buffer.toString();
129 }
130
131 }