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comparison servlet/src/digilib/servlet/PDFCache.java @ 503:fdb824bd57ab digilibPDF

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first functional version of PDFCache after restructuring the code
author cmielack
date Mon, 02 Mar 2009 17:11:26 +0100
parents b2325b33b77b
children 06d7e8c09b11
comparison
equal deleted inserted replaced
502:157d4c7d2343 503:fdb824bd57ab
1 package digilib.servlet; 1 package digilib.servlet;
2 2
3 import java.io.BufferedInputStream;
4 import java.io.File;
5 import java.io.FileInputStream;
6 import java.io.IOException;
3 import java.io.InputStream; 7 import java.io.InputStream;
4 8 import java.util.HashMap;
9
10 import javax.servlet.ServletConfig;
11 import javax.servlet.ServletContext;
12 import javax.servlet.ServletException;
13 import javax.servlet.ServletOutputStream;
5 import javax.servlet.http.HttpServletRequest; 14 import javax.servlet.http.HttpServletRequest;
6 import javax.servlet.http.HttpServletResponse; 15 import javax.servlet.http.HttpServletResponse;
7 16
8 public class PDFCache extends RequestHandler { 17 public class PDFCache extends RequestHandler {
9 18
19 private DigilibConfiguration dlConfig = null;
20
21 public static String cache_directory = "cache/"; // TODO set using dlConfig
22
23 public static String cache_hash_id = "digilib.servlet.PDFCache";
24
25 HashMap<String,Integer> cache_hash = null;
26
10 27
11 public static Integer STATUS_DONE = 0; // document exists in cache 28 public static Integer STATUS_DONE = 0; // document exists in cache
12 29
13 public static Integer STATUS_WIP = 1; // document is "work in progress" 30 public static Integer STATUS_WIP = 1; // document is "work in progress"
14 31
15 public static Integer STATUS_NONEXISTENT = 2; // document does not exist in cache and is not in progress 32 public static Integer STATUS_NONEXISTENT = 2; // document does not exist in cache and is not in progress
16 33
17 public static Integer STATUS_ERROR = 3; // an error occurred while processing the request 34 public static Integer STATUS_ERROR = 3; // an error occurred while processing the request
18 35
36 public static String version = "0.2";
37
38 // TODO functionality for the pre-generation of complete books/chapters using default values
39 // TODO use DLConfig for default values
40 // TODO use JSPs for automatically refreshing waiting-pages and download-pages
41 // TODO register the PDFCache instance globally and implement getters for cache_dir
42
43
44 public void init(ServletConfig config) throws ServletException{
45
46 super.init(config);
47
48
49
50 logger.info("initialized PDFCache v."+version);
51
52 // create and register hashtable
53 ServletContext context = config.getServletContext();
54
55 dlConfig = (DigilibConfiguration) context.getAttribute("digilib.servlet.configuration");
56
57 if (dlConfig == null) {
58 // no Configuration
59 throw new ServletException("No Configuration!");
60 }
61
62 context.setAttribute(cache_hash_id, new HashMap<String,Integer>());
63
64 cache_hash = (HashMap<String,Integer>) context.getAttribute(cache_hash_id);
65
66 if (cache_hash==null){
67 cache_hash = new HashMap<String,Integer>();
68 context.setAttribute(cache_hash_id, cache_hash);
69 }
70
71 // scan the directory
72 scanCacheDirectory();
73
74 }
75
76
77 public void scanCacheDirectory(){
78 // search the cache-directory for existing files and fill them into the Hashtable as STATUS_DONE
79
80 ServletContext context = this.getServletContext();
81 HashMap<String,Integer> cache_hash = (HashMap<String,Integer>) context.getAttribute(cache_hash_id);
82
83 File cache_dir = new File(cache_directory);
84 String[] cached_files = cache_dir.list();
85
86
87 for (String file: cached_files){
88 String docid = file.substring(0,file.length()-4);
89 logger.debug("docid = "+docid);
90 if (file.endsWith(".pdf") && !cache_hash.containsKey(docid)){
91 logger.debug("PDFCache reads in "+file);
92 cache_hash.put(file, STATUS_DONE);
93 }
94 }
95 }
19 96
20 97
21 98
22 @Override 99 @Override
23 public void processRequest(HttpServletRequest request, 100 public void processRequest(HttpServletRequest request,
24 HttpServletResponse response) { 101 HttpServletResponse response) {
25 102
26 // evaluate request ( make a PDFJobDeclaration , get the DocumentId) 103 // evaluate request ( make a PDFJobDeclaration , get the DocumentId)
27 104 PDFJobInformation pdfji = new PDFJobInformation(dlConfig);
28 // check, which state the requested document is in (ready, work in progress, non existent) 105 pdfji.setWithRequest(request);
29 106
30 // if necessary, initialize document generation (and notify the user) 107
31 108 String docid = pdfji.getDocumentId();
32 // send the document 109
33 } 110
34 111 int status = getStatus(docid);
35 @Override 112
36 public void sendFile(InputStream is, HttpServletResponse response, String filename) { 113
37 114
38 } 115 if(status == STATUS_NONEXISTENT){
39 116 createNewPdfDocument(pdfji, docid);
40 public String getDocumentId(PDFJobDeclaration jobdeclaration){ 117 informUser(status, docid, response);
41 // generate an unambiguous ID from the request (this is used for filenames etc) 118 }
42 String id; 119 else if (status == STATUS_DONE){
43 120 try {
44 String fn = jobdeclaration.getAsString("fn"); 121 sendFile(docid, downloadFilename(pdfji), response);
45 String dh = jobdeclaration.getAsString("dh"); 122 } catch (IOException e) {
46 String pgs = jobdeclaration.getAsString("pgs"); 123 e.printStackTrace();
47 124 logger.error(e.getMessage());
48 id = "fn=" + fn + "&dh=" + dh + "&pgs=" + pgs + ".pdf"; 125 }
49 126 }
50 return id; 127 else {
128 informUser(status, docid, response);
129 }
130 }
131
132
133 public void informUser(int status, String documentid, HttpServletResponse response){
134 // depending on the documents status, redirect the user to an appropriate waiting- or download-site
135 // TODO
136
137 if(status == STATUS_NONEXISTENT){
138 // tell the user that the document has to be created before he/she can download it
139 logger.debug("PDFCache: "+documentid+" has STATUS_NONEXISTENT.");
140 }
141 else if(status == STATUS_WIP){
142 logger.debug("PDFCache: "+documentid+" has STATUS_WIP.");
143
144 // estimate remaining work time
145 // tell the user he/she has to wait
146 }
147 else if(status == STATUS_DONE){
148 logger.debug("PDFCache: "+documentid+" has STATUS_DONE.");
149
150 // do nothing or refresh
151 }
152 else {
153 logger.debug("PDFCache: "+documentid+" has STATUS_ERROR.");
154
155 // status == STATUS_ERROR
156 // an error must have occured; show error page
157 }
158
51 } 159 }
52 160
53 161
54 /** check the status of the document corresponding to the documentid */ 162 /** check the status of the document corresponding to the documentid */
55 public Integer getStatus(String documentid){ 163 public Integer getStatus(String documentid){
56 164 // rescan directory? might be useful if more than one instance uses the same cache directory ; Problem: wip-files occur in the list
57 165 if(cache_hash.containsKey(documentid))
58 return 0; 166 return cache_hash.get(documentid);
167 else
168 return STATUS_NONEXISTENT;
169 }
170
171
172 public void createNewPdfDocument(PDFJobInformation pdfji, String filename){
173 // start new worker
174 PDFMaker pdf_maker = new PDFMaker(dlConfig, cache_hash, pdfji,filename);
175 new Thread(pdf_maker, "PDFMaker").start();
176 }
177
178
179 public String downloadFilename(PDFJobInformation pdfji){
180 String filename;
181 filename = "digilib_";
182 filename += pdfji.getImageJobInformation().getAsString("fn");
183 filename += "_pgs" + pdfji.getAsString("pgs");
184 filename += ".pdf";
185
186 return filename;
187 }
188
189 /**
190 * sends a document to the user
191 *
192 * @param cachefile The filename of the document in cache.
193 * @param filename The filename used for downloading.
194 * @param response
195 * @throws IOException
196 */
197 public void sendFile(String cachefile, String filename, HttpServletResponse response) throws IOException{
198 File cached_file = null;
199 FileInputStream fis = null;
200 ServletOutputStream sos = null;
201 BufferedInputStream bis = null;
202
203 try {
204 cached_file = new File(cache_directory + cachefile);
205 fis = new FileInputStream(cached_file);
206 sos = response.getOutputStream();
207 bis = new BufferedInputStream(fis);
208
209 int bytes = 0;
210
211 response.setContentType("application/pdf");
212 response.addHeader("Content-Disposition", "attachment; filename="+filename);
213 response.setContentLength( (int) cached_file.length());
214
215 while ((bytes = bis.read()) != -1){
216 sos.write(bytes);
217 }
218 }
219 catch(Exception e){
220 logger.error(e.getMessage());
221 }
222 finally{
223 // close all streams
224 if (fis != null)
225 fis.close();
226 if (bis != null)
227 bis.close();
228 if (sos != null)
229 sos.close();
230 }
231
59 } 232 }
60 } 233 }