Servlet


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2    * All rights reserved.
3    *
4    * Redistribution and use in source and binary forms, with or without
5    * modification, are permitted provided that the following conditions are met:
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8    * list of conditions and the following disclaimer.
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16   * software without specific prior written permission.
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33   *
34   * For work added by the HSQL Development Group:
35   *
36   * Copyright (c) 2001-2005, The HSQL Development Group
37   * All rights reserved.
38   *
39   * Redistribution and use in source and binary forms, with or without
40   * modification, are permitted provided that the following conditions are met:
41   *
42   * Redistributions of source code must retain the above copyright notice, this
43   * list of conditions and the following disclaimer.
44   *
45   * Redistributions in binary form must reproduce the above copyright notice,
46   * this list of conditions and the following disclaimer in the documentation
47   * and/or other materials provided with the distribution.
48   *
49   * Neither the name of the HSQL Development Group nor the names of its
50   * contributors may be used to endorse or promote products derived from this
51   * software without specific prior written permission.
52   *
53   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
54   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56   * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
57   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
58   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
59   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
60   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
61   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
62   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
63   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
64   */
65  
66  
67  package org.hsqldb;
68  
69  import java.io.DataInputStream  ;
70  import java.io.IOException  ;
71  import java.io.PrintWriter  ;
72  
73  import javax.servlet.ServletConfig  ;
74  import javax.servlet.ServletException  ;
75  import javax.servlet.ServletOutputStream  ;
76  import javax.servlet.http.HttpServletRequest  ;
77  import javax.servlet.http.HttpServletResponse  ;
78  
79  import org.hsqldb.persist.HsqlProperties;
80  import org.hsqldb.rowio.RowInputBinary;
81  import org.hsqldb.rowio.RowOutputBinary;
82  
83  // fredt@users 20020130 - patch 475586 by wreissen@users
84  // fredt@users 20020328 - patch 1.7.0 by fredt - error trapping
85  // fredt@users 20030630 - patch 1.7.2 - new protocol, persistent sessions
86  // fredt@users 20041112 - patch by Willian Crick - use web_inf directory
87  
88  /**
89   * Servlet can act as an interface between the client and the database for the
90   * the client / server mode of HSQL Database Engine. It uses the HTTP protocol
91   * for communication. This class is not required if the included HSQLDB
92   * Weberver is used on the server host. But if the host is running a J2EE
93   * application server or a servlet container such as Tomcat, the Servlet class
94   * can be hosted on this server / container to serve external requests from
95   * external hosts.<p>
96   * The remote applet / application should
97   * use the normal JDBC interfaces to connect to the URL of this servlet. An
98   * example URL is:
99   * <pre>
100  * jdbc:hsqldb:http://localhost.com:8080/servlet/org.hsqldb.Servlet
101  * </pre>
102  * The database path/name is taken from the servlet engine property:
103  * <pre>
104  * hsqldb.server.database
105  * </pre>
106  * <p>
107  * If the database is deployed in the WEB-INF directory of the servlet container,
108  * the property:
109  * <pre>
110  *  hsqldb.server.use_web-inf_path
111  * </pre>
112  * should be set "true" in the web.xml file of the servlet container.
113  * In this case, the database path should begin with a "/".
114  *
115  * From version 1.7.2 JDBC connections via the HTTP protocol are persistent
116  * in the JDBC sense. The JDBC Connection that is established can support
117  * transactions spanning several Statement calls and real PreparedStatement
118  * calls are supported. This class has been rewritten to support the new
119  * features.<p>
120  * (fredt@users)<p>
121  *
122  * Extensively rewritten for HSQLDB.
123  *
124  * @author Thomas Mueller (Hypersonic SQL Group)
125  * @version 1.7.2
126  * @since Hypersonic SQL
127  */
128 public class Servlet extends javax.servlet.http.HttpServlet   {
129 
130     private static final int BUFFER_SIZE = 256;
131     private String             dbType;
132     private String             dbPath;
133     private String             errorStr;
134     private RowOutputBinary  rowOut;
135     private RowInputBinary   rowIn;
136     private int              iQueries;
137 
138     /**
139      * Method declaration
140      *
141      *
142      * @param config
143      */
144     public void init(ServletConfig   config) {
145 
146         try {
147             super.init(config);
148 
149             rowOut = new RowOutputBinary(BUFFER_SIZE);
150             rowIn  = new RowInputBinary(rowOut);
151         } catch (ServletException   e) {
152             log(e.toString());
153         }
154 
155         String   dbStr = getInitParameter("hsqldb.server.database");
156 
157         if (dbStr == null) {
158             dbStr = ".";
159         }
160 
161 // begin WEB-INF patch */
162         String   useWebInfStr =
163             getInitParameter("hsqldb.server.use_web-inf_path");
164 
165         if (!dbStr.equals(".") && "true".equalsIgnoreCase(useWebInfStr)) {
166             dbStr = getServletContext().getRealPath("/") + "WEB-INF" + dbStr;
167         }
168 
169 // end WEB-INF patch
170         HsqlProperties dbURL = DatabaseURL.parseURL(dbStr, false);
171 
172         log("Database filename = " + dbStr);
173 
174         if (dbURL == null) {
175             errorStr = "Bad Database name";
176         } else {
177             dbPath = dbURL.getProperty("database");
178             dbType = dbURL.getProperty("connection_type");
179 
180             try {
181 
182 // loosecannon1@users 1.7.2 patch properties on the JDBC URL
183                 DatabaseManager.getDatabase(dbType, dbPath, dbURL);
184             } catch (HsqlException e) {
185                 errorStr = e.getMessage();
186             }
187         }
188 
189         log(errorStr);
190         log("Initialization completed.");
191     }
192 
193     private static long lModified = 0;
194 
195     /**
196      * Method declaration
197      *
198      *
199      * @param req
200      *
201      * @return
202      */
203     protected long getLastModified(HttpServletRequest   req) {
204 
205         // this is made so that the cache of the http server is not used
206         // maybe there is some other way
207         return lModified++;
208     }
209 
210     /**
211      * Method declaration
212      *
213      *
214      * @param request
215      * @param response
216      *
217      * @throws IOException
218      * @throws ServletException
219      */
220     public void doGet(HttpServletRequest   request,
221                       HttpServletResponse   response)
222                       throws IOException  , ServletException   {
223 
224         String   query = request.getQueryString();
225 
226         if ((query == null) || (query.length() == 0)) {
227             response.setContentType("text/html");
228 
229 // fredt@users 20020130 - patch 1.7.0 by fredt
230 // to avoid caching on the browser
231             response.setHeader("Pragma", "no-cache");
232 
233             PrintWriter   out = response.getWriter();
234 
235             out.println(
236                 "<html><head><title>HSQL Database Engine Servlet</title>");
237             out.println("</head><body><h1>HSQL Database Engine Servlet</h1>");
238             out.println("The servlet is running.<p>");
239 
240             if (errorStr == null) {
241                 out.println("The database is also running.<p>");
242                 out.println("Database name: " + dbType + dbPath + "<p>");
243                 out.println("Queries processed: " + iQueries + "<p>");
244             } else {
245                 out.println("<h2>The database is not running!</h2>");
246                 out.println("The error message is:<p>");
247                 out.println(errorStr);
248             }
249 
250             out.println("</body></html>");
251         }
252     }
253 
254     /**
255      * Method declaration
256      *
257      *
258      * @param request
259      * @param response
260      *
261      * @throws IOException
262      * @throws ServletException
263      */
264     public void doPost(HttpServletRequest   request,
265                        HttpServletResponse   response)
266                        throws IOException  , ServletException   {
267 
268         synchronized (this) {
269             DataInputStream       inStream  = null;
270             ServletOutputStream   outStream = null;
271 
272             try {
273 
274                 // fredt@users - the servlet container, Resin does not return all
275                 // the bytes with one call to input.read(b,0,len) when len > 8192
276                 // bytes, the loop in the Result.read() method handles this
277                 inStream = new DataInputStream  (request.getInputStream());
278 
279                 Result resultIn = Result.read(rowIn, inStream);
280                 Result resultOut;
281 
282                 if (resultIn.mode == ResultConstants.SQLCONNECT) {
283                     try {
284                         Session session = DatabaseManager.newSession(dbType,
285                             dbPath, resultIn.getMainString(),
286                             resultIn.getSubString(), null);
287 
288                         resultOut = new Result(ResultConstants.UPDATECOUNT);
289                         resultOut.sessionID = session.getId();
290                     } catch (HsqlException e) {
291                         resultOut = new Result(e, null);
292                     }
293                 } else {
294                     int dbId      = resultIn.databaseID;
295                     int sessionId = resultIn.sessionID;
296                     Session session = DatabaseManager.getSession(dbId,
297                         sessionId);
298 
299                     resultOut = session.execute(resultIn);
300                 }
301 
302                 rowOut.reset();
303                 resultOut.write(rowOut);
304 
305                 //
306                 response.setContentType("application/octet-stream");
307                 response.setContentLength(rowOut.size());
308 
309                 //
310                 outStream = response.getOutputStream();
311 
312                 outStream.write(rowOut.getOutputStream().getBuffer(), 0,
313                                 rowOut.getOutputStream().size());
314 
315                 iQueries++;
316             } catch (HsqlException e) {}
317             finally {
318                 if (outStream != null) {
319                     outStream.close();
320                 }
321 
322                 if (inStream != null) {
323                     inStream.close();
324                 }
325             }
326         }
327 
328         // Trace.printSystemOut("Queries processed: "+iQueries+"  \n");
329     }
330 }
331
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