1 /*
2 * ========================================================================
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one or more
5 * contributor license agreements. See the NOTICE file distributed with
6 * this work for additional information regarding copyright ownership.
7 * The ASF licenses this file to You under the Apache License, Version 2.0
8 * (the "License"); you may not use this file except in compliance with
9 * the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 * ========================================================================
20 */
21 package org.apache.cactus.integration.ant.util;
22
23 import java.io.IOException;
24 import java.io.InputStream;
25 import java.net.HttpURLConnection;
26 import java.net.URL;
27
28 /**
29 * Support class that probes a URL.
30 *
31 *
32 * @version $Id: HttpProbe.java,v 1.0 2005/08/29 10:19:57 xnguyen Exp $
33 */
34 public class HttpProbe
35 {
36
37 // Instance Variables ------------------------------------------------------
38
39 /**
40 * The URL.
41 */
42 private URL url;
43
44 // Constructors ------------------------------------------------------------
45
46 /**
47 * Constructor.
48 *
49 * @param theUrl The Url
50 */
51 public HttpProbe(URL theUrl)
52 {
53 this.url = theUrl;
54 }
55
56 /**
57 * In thread tests whether we are able to connect to the
58 * HTTP server identified by the
59 * specified URL. The caller thread is blocked.
60 * @param theWaitedTime The time waiting
61 * @param theCheckedInterval The interval to check
62 * @throws InterruptedException If the current Thread is interupted
63 * @throws IOException If there is error with reading
64 * @return the HTTP response code or -1 if no connection could be
65 * established
66 */
67 public boolean timeout(long theWaitedTime, long theCheckedInterval)
68 throws InterruptedException, IOException
69 {
70 //Ping the container
71 //Continuously try calling the test URL until it succeeds or
72 // until a timeout is reached (we then throw a build exception).
73 long startTime = System.currentTimeMillis();
74 int responseCode = -1;
75 do
76 {
77 if ((System.currentTimeMillis() - startTime) > theWaitedTime)
78 {
79 return true;
80
81 }
82
83 sleep(theCheckedInterval);
84
85 responseCode = testConnectivity();
86
87
88 } while (!isAvailable(responseCode));
89
90 return false;
91
92 }
93
94
95 /**
96 * Tests whether we are able to connect to the HTTP server identified by the
97 * specified URL.
98 * @throws IOException If there is reading error
99 * @return the HTTP response code or -1 if no connection could be
100 * established
101 */
102 public int testConnectivity() throws IOException
103 {
104 int code = -1;
105 HttpURLConnection connection = null;
106
107 connection = (HttpURLConnection) url.openConnection();
108 connection.setRequestProperty("Connection", "close");
109 connection.connect();
110 code = connection.getResponseCode();
111 readFully(connection);
112 connection.disconnect();
113
114 return code;
115 }
116
117
118 /**
119 * Tests whether an HTTP return code corresponds to a valid connection
120 * to the test URL or not. Success is 200 up to but excluding 300.
121 *
122 * @param theCode the HTTP response code to verify
123 * @return <code>true</code> if the test URL could be called without error,
124 * <code>false</code> otherwise
125 */
126 private boolean isAvailable(int theCode)
127 {
128 boolean result;
129 if ((theCode != -1) && (theCode < 300))
130 {
131 result = true;
132 }
133 else
134 {
135 result = false;
136 }
137 return result;
138 }
139
140 /**
141 * Retrieves the server name of the container.
142 *
143 * @return The server name, or <code>null</code> if the server name could
144 * not be retrieved
145 * @throws IOException If there is error when reading
146 */
147 private String retrieveServerName() throws IOException
148 {
149 String retVal = null;
150
151 HttpURLConnection connection =
152 (HttpURLConnection) url.openConnection();
153 connection.connect();
154 retVal = connection.getHeaderField("Server");
155 connection.disconnect();
156
157 return retVal;
158 }
159
160 /**
161 * Fully reads the input stream from the passed HTTP URL connection to
162 * prevent (harmless) server-side exception.
163 *
164 * @param theConnection the HTTP URL connection to read from
165 * @exception IOException if an error happens during the read
166 */
167 private void readFully(HttpURLConnection theConnection)
168 throws IOException
169 {
170 // Only read if there is data to read ... The problem is that not
171 // all servers return a content-length header. If there is no header
172 // getContentLength() returns -1. It seems to work and it seems
173 // that all servers that return no content-length header also do
174 // not block on read() operations!
175 if (theConnection.getContentLength() != 0)
176 {
177 byte[] buf = new byte[256];
178 InputStream in = theConnection.getInputStream();
179 while (in.read(buf) != -1)
180 {
181 // Make sure we read all the data in the stream
182 }
183 }
184 }
185
186 /**
187 * Pauses the current thread for the specified amount.
188 *
189 * @param theMs The time to sleep in milliseconds
190 * @throws InterruptedException If the sleeping thread is interrupted
191 */
192 private void sleep(long theMs) throws InterruptedException
193 {
194
195 Thread.sleep(theMs);
196
197 }
198
199 // Private Methods ---------------------------------------------------------
200
201
202
203 }