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.step3.server;
21
22 import java.awt.Color;
23 import java.awt.Font;
24 import java.awt.Graphics;
25 import java.awt.image.BufferedImage;
26
27 import javax.management.MBeanServer;
28 import javax.management.ObjectName;
29
30 import org.apache.mina.core.service.IoHandlerAdapter;
31 import org.apache.mina.core.session.IoSession;
32 import org.apache.mina.example.imagine.step1.ImageRequest;
33 import org.apache.mina.example.imagine.step1.ImageResponse;
34 import org.apache.mina.integration.jmx.IoSessionMBean;
35 import org.slf4j.Logger;
36 import org.slf4j.LoggerFactory;
37
38 /**
39 * server-side {@link org.apache.mina.core.service.IoHandler}
40 *
41 * @author The Apache MINA Project (dev@mina.apache.org)
42 * @version $Rev$, $Date$
43 */
44
45 public class ImageServerIoHandler extends IoHandlerAdapter {
46
47 private final static String characters = "mina rocks abcdefghijklmnopqrstuvwxyz0123456789";
48
49 public static final String INDEX_KEY = ImageServerIoHandler.class.getName() + ".INDEX";
50
51 private Logger logger = LoggerFactory.getLogger(this.getClass());
52
53 private MBeanServer mBeanServer;
54
55 /**
56 * Creates a new instance of ImageServerIoHandler. For this step, we pass in a reference
57 * to the MBeanServer. This instance will be used to register new IoSession objects
58 * so that the JMX subsystem can report statistics on the sessions.
59 *
60 * @param mBeanServer
61 * The JMX MBeanServer that will register the sessions
62 */
63 public ImageServerIoHandler( MBeanServer mBeanServer ) {
64 this.mBeanServer = mBeanServer;
65 }
66
67 /**
68 * This method is called first when a new connection to the server is made. In here we will set
69 * up the JMX session MBean.
70 *
71 * @see org.apache.mina.core.service.IoHandlerAdapter#sessionCreated(org.apache.mina.core.session.IoSession)
72 */
73 public void sessionCreated( IoSession session ) throws Exception
74 {
75 // create a session MBean in order to load into the MBeanServer and allow
76 // this session to be managed by the JMX subsystem.
77 IoSessionMBean sessionMBean = new IoSessionMBean( session );
78
79 // create a JMX ObjectName. This has to be in a specific format.
80 ObjectName sessionName = new ObjectName( session.getClass().getPackage().getName() +
81 ":type=session,name=" + session.getClass().getSimpleName() + "-" + session.getId());
82
83 // register the bean on the MBeanServer. Without this line, no JMX will happen for
84 // this session
85 mBeanServer.registerMBean( sessionMBean, sessionName );
86 }
87
88 /**
89 * Called when the session is opened, which will come after the session created.
90 *
91 * @see org.apache.mina.core.service.IoHandlerAdapter#sessionOpened(org.apache.mina.core.session.IoSession)
92 */
93 public void sessionOpened(IoSession session) throws Exception {
94
95 // set the index to zero. This is used to determine how the build the
96 // string that is sent to the client.
97 session.setAttribute(INDEX_KEY, 0);
98 }
99
100 /**
101 * This method will be called whenever an exception occurs. For this handler,
102 * the logger will generate a warning message.
103 *
104 * @see org.apache.mina.core.service.IoHandlerAdapter#exceptionCaught(org.apache.mina.core.session.IoSession, java.lang.Throwable)
105 */
106 public void exceptionCaught(IoSession session, Throwable cause) throws Exception {
107 logger.warn(cause.getMessage(), cause);
108 }
109
110 /**
111 * Handle incoming messages.
112 *
113 * @see org.apache.mina.core.service.IoHandlerAdapter#messageReceived(org.apache.mina.core.session.IoSession, java.lang.Object)
114 */
115 public void messageReceived(IoSession session, Object message) throws Exception {
116 ImageRequest request = (ImageRequest) message;
117 String text1 = generateString(session, request.getNumberOfCharacters());
118 String text2 = generateString(session, request.getNumberOfCharacters());
119 BufferedImage image1 = createImage(request, text1);
120 BufferedImage image2 = createImage(request, text2);
121 ImageResponse response = new ImageResponse(image1, image2);
122 session.write(response);
123 }
124
125 /**
126 * Create an image using the specified request and the text.
127 *
128 * @param request
129 * Determines the height and width of the image
130 * @param text
131 * The text that is placed in the image
132 * @return
133 * a BufferedImage representing the text.
134 */
135 private BufferedImage createImage(ImageRequest request, String text) {
136 BufferedImage image = new BufferedImage(request.getWidth(), request.getHeight(), BufferedImage.TYPE_BYTE_INDEXED);
137 Graphics graphics = image.createGraphics();
138 graphics.setColor(Color.YELLOW);
139 graphics.fillRect(0, 0, image.getWidth(), image.getHeight());
140 Font serif = new Font("serif", Font.PLAIN, 30);
141 graphics.setFont(serif);
142 graphics.setColor(Color.BLUE);
143 graphics.drawString(text, 10, 50);
144 return image;
145 }
146
147 /**
148 * Generate a string based on the 'characters' field in this class. The
149 * characters that make up the string are based on the session
150 * attribute "INDEX_KEY"
151 *
152 * @param session
153 * The {@link IoSession} object that will provide the INDEX_KEY attribute
154 * @param length
155 * The length that the String will be
156 * @return
157 * The generated String
158 */
159 private String generateString(IoSession session, int length) {
160 Integer index = (Integer) session.getAttribute(INDEX_KEY);
161 StringBuffer buffer = new StringBuffer(length);
162 while (buffer.length() < length) {
163 buffer.append(characters.charAt(index));
164 index++;
165 if (index >= characters.length()) {
166 index = 0;
167 }
168 }
169 session.setAttribute(INDEX_KEY, index);
170 return buffer.toString();
171 }
172
173 }