Mercurial > hg > digilib-old
annotate servlet/src/digilib/servlet/PDFCache.java @ 499:87d2ed21bdec Root_digilibPDF
changed generation of documentID in PDFCache
| author | cmielack |
|---|---|
| date | Fri, 13 Feb 2009 11:08:19 +0100 |
| parents | 86b5589f38db |
| children |
| rev | line source |
|---|---|
| 495 | 1 package digilib.servlet; |
| 2 | |
| 3 import java.io.BufferedInputStream; | |
| 4 import java.io.File; | |
| 5 import java.io.FileInputStream; | |
| 6 import java.io.IOException; | |
| 7 import java.util.Hashtable; | |
| 8 | |
| 9 import javax.servlet.ServletConfig; | |
| 10 import javax.servlet.ServletContext; | |
| 11 import javax.servlet.ServletException; | |
| 12 import javax.servlet.ServletOutputStream; | |
| 13 import javax.servlet.http.HttpServlet; | |
| 14 import javax.servlet.http.HttpServletRequest; | |
| 15 import javax.servlet.http.HttpServletResponse; | |
| 16 | |
| 17 import org.apache.log4j.Logger; | |
| 18 | |
| 19 | |
| 20 /** | |
| 21 * PDF request manager with caching capabilities. | |
| 22 * This is a very early and dirty but functional version and will | |
| 23 * (hopefully soon) be replaced by a parallelized and more sophisticated one. | |
| 24 * | |
| 25 * @author cmielack | |
| 26 * | |
| 27 */ | |
| 28 | |
| 29 public class PDFCache extends HttpServlet { | |
| 30 | |
| 31 private static final long serialVersionUID = 1L; | |
| 32 | |
| 33 | |
| 34 private static int STATUS_NONEXISTENT = 0; // the document does not exist and is not under construction | |
| 35 private static int STATUS_DONE = 1; // the document exists and can be downloaded | |
| 36 private static int STATUS_PENDING = 2; // the document is "under construction" | |
| 37 private static int STATUS_ERROR = 3; // an error occurred while processing the request | |
| 38 | |
| 39 private static String cache_directory = "cache/"; // the path (relative to the tomcat base-directory) where cached | |
| 40 // files are stored | |
| 41 | |
| 42 private static String cache_hash_id = "digilib.servlet.PDFCache"; | |
| 43 | |
| 44 | |
| 45 private static Logger logger = Logger.getLogger("digilib.servlet"); | |
| 46 | |
| 47 | |
| 48 public void init(ServletConfig config){ | |
| 49 // initialize the PDFCache | |
| 50 | |
| 51 logger.debug("Initializing PDFCache"); | |
| 52 | |
| 53 try { | |
| 54 super.init(config); | |
| 55 } catch (ServletException e) { | |
| 56 e.printStackTrace(); | |
| 57 } | |
| 58 | |
| 59 ServletContext context = this.getServletContext(); | |
| 60 | |
| 61 context.setAttribute(cache_hash_id, new Hashtable<String,Integer>()); | |
| 62 | |
| 63 Hashtable<String,Integer> cache_hash = (Hashtable<String,Integer>) context.getAttribute(cache_hash_id); | |
| 64 | |
| 65 if (cache_hash==null){ | |
| 66 cache_hash = new Hashtable<String,Integer>(); | |
| 67 context.setAttribute(cache_hash_id, cache_hash); | |
| 68 } | |
| 69 | |
| 70 // search the cache-directory for existing files and fill them into the Hashtable as STATUS_DONE | |
| 71 File cache_dir = new File(cache_directory); | |
| 72 String[] cached_files = cache_dir.list(); | |
| 73 | |
| 74 | |
| 75 for (String file: cached_files){ | |
| 76 if (file.endsWith(".pdf")){ | |
| 77 logger.debug("cache found "+file); | |
| 78 cache_hash.put(file, 1); | |
| 79 } | |
| 80 } | |
| 81 | |
| 82 } | |
| 83 | |
| 84 | |
| 85 public String getDocumentId(HttpServletRequest request){ | |
| 86 // generate an unambiguous ID from the request (this is used for filenames etc) | |
| 87 String id; | |
| 499 | 88 |
| 89 String fn = request.getParameter("fn"); | |
| 90 String dh = request.getParameter("dh"); | |
| 91 String pgs = request.getParameter("pgs"); | |
| 495 | 92 |
| 499 | 93 id = "fn=" + fn + "&dh=" + dh + "&pgs=" + pgs + ".pdf"; |
| 495 | 94 |
| 95 return id; | |
| 96 } | |
| 97 | |
| 98 | |
| 99 public void doGet(HttpServletRequest request, HttpServletResponse response){ | |
| 100 | |
| 101 // get the status of the Document specified by the request ... | |
| 102 int status = this.getStatus(request); | |
| 103 | |
| 104 | |
| 105 if (status == STATUS_DONE) { | |
| 106 // ... and if the file already exists, send it ... | |
| 107 try { | |
| 108 sendFile(request,response); | |
|
498
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
109 |
| 495 | 110 } catch (IOException e) { |
| 111 // TODO Auto-generated catch block | |
| 112 e.printStackTrace(); | |
| 113 } | |
| 114 } | |
| 115 | |
| 116 else if (status == STATUS_PENDING){ | |
| 117 // ... if it is in the works, notify the user about it ... | |
| 118 } | |
| 119 else if (status == STATUS_NONEXISTENT){ | |
| 120 // ... or else, generate the file and inform the user about the estimated generation-time | |
| 121 try { | |
|
498
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
122 createFile(request, response); |
| 499 | 123 response.sendRedirect(request.getRequestURI()+'?'+request.getQueryString()+"&done=true"); // refresh the browser after finishing the file |
| 495 | 124 } catch (ServletException e) { |
| 125 // TODO Auto-generated catch block | |
| 126 e.printStackTrace(); | |
| 127 } catch (IOException e) { | |
| 128 // TODO Auto-generated catch block | |
| 129 e.printStackTrace(); | |
|
498
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
130 } catch (InterruptedException e) { |
|
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
131 // TODO Auto-generated catch block |
|
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
132 e.printStackTrace(); |
| 495 | 133 } |
| 134 } | |
| 135 else { | |
| 136 // if an error occurred ... | |
| 137 } | |
| 138 } | |
| 139 | |
| 140 public int getStatus(HttpServletRequest request){ | |
| 141 | |
| 142 String documentId = getDocumentId(request); | |
| 143 | |
| 144 ServletContext context = this.getServletContext(); | |
| 145 Hashtable<String,Integer> documentStatus = (Hashtable<String,Integer>) context.getAttribute(cache_hash_id); | |
| 146 | |
| 147 int status = STATUS_NONEXISTENT; | |
| 148 | |
| 149 if (documentStatus.containsKey(documentId)){ | |
| 150 status = documentStatus.get(documentId); | |
| 151 } | |
| 152 | |
| 153 return status; | |
| 154 } | |
| 155 | |
| 156 public void sendFile(HttpServletRequest request, HttpServletResponse response) throws IOException{ | |
| 157 // send the file specified by the request to the response | |
| 158 | |
| 159 String filename = getDocumentId(request); | |
| 160 File cached_file = null; | |
| 161 FileInputStream fis = null; | |
| 162 ServletOutputStream sos = null; | |
| 163 BufferedInputStream bis = null; | |
| 164 | |
| 165 try { | |
| 166 cached_file = new File(this.cache_directory + filename); | |
| 167 fis = new FileInputStream(cached_file); | |
| 168 sos = response.getOutputStream(); | |
| 169 bis = new BufferedInputStream(fis); | |
| 170 int bytes = 0; | |
| 171 | |
| 497 | 172 String fn = request.getParameter("fn"); |
| 173 String pgs = request.getParameter("pgs"); | |
| 174 | |
| 495 | 175 response.setContentType("application/pdf"); |
| 497 | 176 response.addHeader("Content-Disposition", "attachment; filename="+fn+"_"+pgs+".pdf"); |
| 495 | 177 response.setContentLength( (int) cached_file.length()); |
| 178 | |
| 179 logger.debug("Sending document "+filename+" to the user."); | |
| 180 | |
| 181 while ((bytes = bis.read()) != -1){ | |
| 182 sos.write(bytes); | |
| 183 } | |
| 184 } | |
| 185 catch(Exception e){ | |
| 186 logger.error(e.getMessage()); | |
| 187 } | |
| 188 finally{ | |
| 189 // close all streams | |
| 190 if (fis != null) | |
| 191 fis.close(); | |
| 192 if (bis != null) | |
| 193 bis.close(); | |
| 194 if (sos != null) | |
| 195 sos.close(); | |
| 196 } | |
| 197 } | |
| 198 | |
|
498
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
199 public void createFile(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, InterruptedException{ |
| 495 | 200 // use MakePDF to generate a new Document and put it into the cache-directory |
| 201 | |
| 202 // get global instance of MakePDF | |
| 203 MakePDF mpdf = (MakePDF) this.getServletContext().getAttribute("digilib.servlet.MakePDF"); | |
| 204 | |
| 205 | |
| 206 if (mpdf==null){ | |
| 207 mpdf = new MakePDF(); | |
| 208 logger.debug("didn't find MakePDF-Object"); | |
| 209 } | |
| 210 | |
| 211 String filename = this.cache_directory + this.getDocumentId(request); | |
| 212 | |
| 213 logger.debug("createFile is going to create file "+filename); | |
| 214 | |
| 215 mpdf.doCreate(request,response,filename); // set the parameters and ... | |
| 216 mpdf.run(); // ... start generating the pdf | |
|
498
86b5589f38db
added a sendRedirect after the creation of a PDF so that the user that requested the document gets to download it upon completion
cmielack
parents:
497
diff
changeset
|
217 |
| 495 | 218 //new Thread(mpdf,"MakePDF").start(); |
| 219 } | |
| 220 } |