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 */
39
40 public class ImageServerIoHandler extends IoHandlerAdapter {
41
42 private final static String characters = "mina rocks abcdefghijklmnopqrstuvwxyz0123456789";
43
44 public static final String INDEX_KEY = ImageServerIoHandler.class.getName() + ".INDEX";
45
46 private static Logger LOGGER = LoggerFactory.getLogger(ImageServerIoHandler.class);
47
48 /**
49 * Called when the session is opened, which will come after the session created.
50 *
51 * @see org.apache.mina.core.service.IoHandlerAdapter#sessionOpened(org.apache.mina.core.session.IoSession)
52 */
53 public void sessionOpened(IoSession session) throws Exception {
54 session.setAttribute(INDEX_KEY, 0);
55 }
56
57 /**
58 * This method will be called whenever an exception occurs. For this handler,
59 * the logger will generate a warning message.
60 *
61 * @see org.apache.mina.core.service.IoHandlerAdapter#exceptionCaught(org.apache.mina.core.session.IoSession, java.lang.Throwable)
62 */
63 public void exceptionCaught(IoSession session, Throwable cause) throws Exception {
64 LOGGER.warn(cause.getMessage(), cause);
65 }
66
67 /**
68 * Handle incoming messages.
69 *
70 * @see org.apache.mina.core.service.IoHandlerAdapter#messageReceived(org.apache.mina.core.session.IoSession, java.lang.Object)
71 */
72 public void messageReceived(IoSession session, Object message) throws Exception {
73 ImageRequest request = (ImageRequest) message;
74 String text1 = generateString(session, request.getNumberOfCharacters());
75 String text2 = generateString(session, request.getNumberOfCharacters());
76 BufferedImage image1 = createImage(request, text1);
77 BufferedImage image2 = createImage(request, text2);
78 ImageResponse response = new ImageResponse(image1, image2);
79 session.write(response);
80 }
81
82 /**
83 * Create an image using the specified request and the text.
84 *
85 * @param request
86 * Determines the height and width of the image
87 * @param text
88 * The text that is placed in the image
89 * @return
90 * a BufferedImage representing the text.
91 */
92 private BufferedImage createImage(ImageRequest request, String text) {
93 BufferedImage image = new BufferedImage(request.getWidth(), request.getHeight(), BufferedImage.TYPE_BYTE_INDEXED);
94 Graphics graphics = image.createGraphics();
95 graphics.setColor(Color.YELLOW);
96 graphics.fillRect(0, 0, image.getWidth(), image.getHeight());
97 Font serif = new Font("serif", Font.PLAIN, 30);
98 graphics.setFont(serif);
99 graphics.setColor(Color.BLUE);
100 graphics.drawString(text, 10, 50);
101 return image;
102 }
103
104 /**
105 * Generate a string based on the 'characters' field in this class. The
106 * characters that make up the string are based on the session
107 * attribute "INDEX_KEY"
108 *
109 * @param session
110 * The {@link IoSession} object that will provide the INDEX_KEY attribute
111 * @param length
112 * The length that the String will be
113 * @return
114 * The generated String
115 */
116 private String generateString(IoSession session, int length) {
117 Integer index = (Integer) session.getAttribute(INDEX_KEY);
118 StringBuffer buffer = new StringBuffer(length);
119 while (buffer.length() < length) {
120 buffer.append(characters.charAt(index));
121 index++;
122 if (index >= characters.length()) {
123 index = 0;
124 }
125 }
126 session.setAttribute(INDEX_KEY, index);
127 return buffer.toString();
128 }
129
130 }