I added a step in my application to persist files via GridFS and added a metadata field called "processed" to work as a flag for a scheduled task that retrieves the new file and sends it on for processing. Since the Java driver for GridFS doesn't have a method allowing metadata to be updated I used MongoCollection for the "fs.files" collection to update "metadata.processing" to true.
I use GridFSBucket.find(eq("metadata.processed", false) to get the new files for processing and then update metadata.processed to true once processing is completed. This works if I add a new file while the application is running. However, if I have an existing file with "metadata.processed" set to false and start the application, the above find call returns no results. Similarly if I have a file that was already processed and I set the "metadata.processed" field back to false, the above find call also ceases working.
private static final String FILTER_STR = "'{'\"filename\" : \"{0}\"'}'";
private static final String UPDATE_STR =
"'{'\"$set\": '{'\"metadata.processed\": \"{0}\"'}}'";
#Autowired
private GridFSBucketFactory gridFSBucketFactory;
#Autowired
private MongoCollectionFactory mongoCollectionFactory;
public void storeFile(String filename, DateTime publishTime,
InputStream inputStream) {
if (fileExists(filename)) {
LOGGER.info("File named {} already exists.", filename);
} else {
uploadToGridFS(filename, publishTime, inputStream);
LOGGER.info("Stored file named {}.", filename);
}
}
public GridFSDownloadStream getFile(BsonValue id) {
return gridFSBucketFactory.getGridFSBucket().openDownloadStream(id);
}
public GridFSDownloadStream getFile(String filename) {
final GridFSFile file = getGridFSFile(filename);
return file == null ? null : getFile(file.getId());
}
public GridFSFindIterable getUnprocessedFiles() {
return gridFSBucketFactory.getGridFSBucket()
.find(eq("metadata.processed", false));
}
public void setProcessed(String filename, boolean isProcessed) {
final BasicDBObject filter =
BasicDBObject.parse(format(FILTER_STR, filename));
final BasicDBObject update =
BasicDBObject.parse(format(UPDATE_STR, isProcessed));
if (updateOne(filter, update)) {
LOGGER.info("Set metadata for {} to {}", filename, isProcessed);
}
}
private void uploadToGridFS(String filename, DateTime publishTime,
InputStream inputStream) {
gridFSBucketFactory.getGridFSBucket().uploadFromStream(filename,
inputStream, createMetadata(publishTime));
}
private GridFSUploadOptions createMetadata(DateTime publishTime) {
final Document metadata = new Document();
metadata.put("processed", false);
// metadata.put("publishTime", publishTime.toString());
return new GridFSUploadOptions().metadata(metadata);
}
private boolean fileExists(String filename) {
return getGridFSFile(filename) != null;
}
private GridFSFile getGridFSFile(String filename) {
return gridFSBucketFactory.getGridFSBucket()
.find(eq("filename", filename)).first();
}
private boolean updateOne(BasicDBObject filter, BasicDBObject update) {
try {
mongoCollectionFactory.getFsFilesCollection().updateOne(filter,
update, new UpdateOptions().upsert(true));
} catch (final MongoException e) {
LOGGER.error(
"The following failed to update, filter:{0} update:{1}",
filter, update, e);
return false;
}
return true;
}
Any idea what I can do to ensure:
GridFSBucket.find(eq("metadata.processed", false)
returns the proper results for existing files and/or files that have had the metadata changed?
The issue was due to setting the metadata.processed value as a String vs a boolean.
When initially creating the metadata I set its value with a boolean:
private GridFSUploadOptions createMetadata(DateTime publishTime) {
final Document metadata = new Document();
metadata.put("processed", false);
// metadata.put("publishTime", publishTime.toString());
return new GridFSUploadOptions().metadata(metadata);
}
And later I check for a boolean:
public GridFSFindIterable getUnprocessedFiles() {
return gridFSBucketFactory.getGridFSBucket()
.find(eq("metadata.processed", false));
}
But when updating the metadata using the "fs.files" MongoCollection I incorrectly added quotes around the boolean value here:
private static final String UPDATE_STR =
"'{'\"$set\": '{'\"metadata.processed\": \"{0}\"'}}'";
Which caused the metadata value to be saved as a String vs a boolean.
Related
I am new to Java and Spring Framework, and I'm learning it by a file upload example. I have a controller for uploading of a file. Before I save anything to DB, I would like to check if the file with the same name already exists and return an error message for it. This is how the controller looks like:
#PostMapping("/file-upload")
public String postFile(#RequestParam("fileUpload") MultipartFile fileUpload, Authentication authentication, Model model) throws IOException {
if(fileUpload.isEmpty()) {
model.addAttribute("success",false);
model.addAttribute("message","No file selected to upload!");
return "home";
}
if(fileService.getByFilename(fileUpload.getOriginalFilename()) != null) {
model.addAttribute("success",false);
model.addAttribute("message","File with that name already exists");
return "home";
}
User user = this.userService.getUser(authentication.getName());
Integer userId = user.getUserId();
fileService.createFile(fileUpload, userId);
model.addAttribute("success",true);
model.addAttribute("message","New File added successfully!");
return "home";
}
And this is the fileService getByFilename method:
public File getByUsername(String filename) {
return fileMapper.getByUsername(filename);
}
And finally fileMapper getByFilename:
#Select("SELECT * FROM FILES WHERE filename = #{filename}")
File getByUsername(String filename);
But, when I try to upload a file like that, I get an error:
There was an unexpected error (type=Internal Server Error,
status=500). Error attempting to get column 'FILEDATA' from result
set. Cause: org.h2.jdbc.JdbcSQLDataException: Data conversion error
converting
This is how the table looks like:
CREATE TABLE IF NOT EXISTS FILES (
fileId INT PRIMARY KEY auto_increment,
filename VARCHAR,
contenttype VARCHAR,
filesize VARCHAR,
userid INT,
filedata BLOB,
foreign key (userid) references USERS(userid)
);
How should I fix this?
Here is the link to the repo.
This is the File class:
package com.udacity.jwdnd.course1.cloudstorage.model;
public class File {
private Integer fileId;
private String filename;
private String contenttype;
private Long filesize;
private byte[] filedata;
private Integer userid;
public File(Integer fileId, String filename, String contenttype, Long filesize, byte[] filedata, Integer userid) {
this.fileId = fileId;
this.filename = filename;
this.contenttype = contenttype;
this.filesize = filesize;
this.filedata = filedata;
this.userid = userid;
}
public Integer getFileId() {
return fileId;
}
public void setFileId(Integer fileId) {
this.fileId = fileId;
}
public String getFilename() {
return filename;
}
public void setFilename(String filename) {
this.filename = filename;
}
public String getContenttype() {
return contenttype;
}
public void setContenttype(String contenttype) {
this.contenttype = contenttype;
}
public Long getFilesize() {
return filesize;
}
public void setFilesize(Long filesize) {
this.filesize = filesize;
}
public byte[] getFiledata() {
return filedata;
}
public void setFiledata(byte[] filedata) {
this.filedata = filedata;
}
public Integer getUserid() {
return userid;
}
public void setUserid(Integer userid) { this.userid = userid; }
}
The structure of your table strongly suggests that a single row contains all the data: It does not represent a file at all, and there is no file on your file system: There is a bunch of binary data in the filedata column.
It is not possible to just treat this as a java.io.File object, which is a very light wrapper around a physical file on your file system (really - just check it out, File has one field, of type String, containing a path. That's all it has).
Therefore you just can't do what you want here. You need to find an alternative:
Save the data to an actual file
This involves having some sort of store on the disk, perhaps a tmp dir, where you explicitly write out all the blob data. You'll need to worry about clearing this stuff out or you're going to grow endless files in there.
Who cares about files?
Why do you NEED a file object? You should build software to be as abstract as seems reasonable at the time, and 'I need a file' is rarely the right level. The right level is usually either 'byte array' or 'InputStream' or something similar. Fix your program's flow so that they need only a byte array or better yet an inputstream and use JDBC's blob functionality to take care of this (I don't actually know how to unlock this using spring; you may have to write some code instead of just an #Select annotated method.
As shown in the code below, we have an FtpInboundFileSynchronizingMessageSource with a FileSystemPersistentAcceptOnceFileListFilter using PropertiesPersistingMetadataStore.
#Bean
public PropertiesPersistingMetadataStore getMetadataStore() {
final PropertiesPersistingMetadataStore metadataStore = new PropertiesPersistingMetadataStore() {
#Override
public String putIfAbsent(final String key, final String value) {
try {
super.afterPropertiesSet();
} catch (final Exception e) {
e.printStackTrace();
}
return super.putIfAbsent(key, value);
}
};
metadataStore.setBaseDirectory(getRegistryValue("LOCALMETASTOREDIRECTORY"));
return metadataStore;
}
#Bean
#InboundChannelAdapter(value = "CSVChannel", poller = #Poller(fixedRate = "30000", maxMessagesPerPoll = "1"))
public MessageSource<File> ftpMessageSource() {
final String METHODNAME = "ftpMessageSource()";
if (LoggingHelper.isEntryExitTraceEnabled(LOGGER)) {
LOGGER.entering(CLASSNAME, METHODNAME);
}
final Comparator<File> fileLastModifiedDateComparator = new Comparator<File>() {
#Override
public int compare(final File f1, final File f2) {
return Long.valueOf(f1.lastModified())
.compareTo(f2.lastModified());
}
};
final FtpInboundFileSynchronizingMessageSource source = new FtpInboundFileSynchronizingMessageSource(ftpInboundFileSynchronizer(), fileLastModifiedDateComparator);
source.setLocalDirectory(new File(getRegistryValue("LOCALDIRECTORY")));
final FileSystemPersistentAcceptOnceFileListFilter fileSystemPersistentAcceptOnceFileListFilter = new FileSystemPersistentAcceptOnceFileListFilter(getMetadataStore(),
getRegistryValue("REMOTEFILENAMEPATTERN_ANAG_CLI"));
fileSystemPersistentAcceptOnceFileListFilter.setFlushOnUpdate(true);
source.setLocalFilter(fileSystemPersistentAcceptOnceFileListFilter);
if (LoggingHelper.isEntryExitTraceEnabled(LOGGER)) {
LOGGER.exiting(CLASSNAME, METHODNAME);
}
return source;
}
We have 4 instances of the application running in production and the local directory, meta store directory are all on a location shared by all 4 instances.
The problem we facing now is we are seeing invalid characters written in the metadata-store.properties file and sometimes there is some process writing this character \u0000 continuously and that causes the file to grow in big size, like 1GB in few minutes. And since the metadata is read in to memory by the framework that is causing outofmemoryexception when the file is very big.
Please see below some entries from the metadata-store.properties file below.
ANAG_CLI_*.CSV/opt/user-integration/anagcli/input/20200609113855907_ANAG_CLI_20200609113846.CSV.a=1591695480000
\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000=
ANAG_CLI_*.CSV/opt/user-integration/anagcli/input/20200610105125916_ANAG_CLI_20200610105118.CSV.a.writing=1591779085951
\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000=
\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000=
\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000=
\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000=
ANAG_CLI_*.CSV/opt/user-integration/anagcli/input/20200609133155929_ANAG_CLI_20200609133146.CSV.a=1591702315917
Is it safe to use the PropertiesPersistingMetadataStore like this in a shared location between more than one application instances? How to understand what is causing this invalid character issue and how to avoid this?
Any help would be appreciated!
I have an app where I filter messages according to some rules(existing some keywords or regexps). These rules are to be stored in .properties file(as they must be persistent). I've figured out how to read data from this file. here is the part of the code:
public class Config {
private static final Config ourInstance = new Config();
private static final CompositeConfiguration prop = new CompositeConfiguration();
public static Config getInstance() {
return ourInstance;
}
public Config(){
}
public synchronized void load() {
try {
prop.addConfiguration(new SystemConfiguration());
System.out.println("Loading /rules.properties");
final PropertiesConfiguration p = new PropertiesConfiguration();
p.setPath("/home/mikhail/bzrrep/DLP/DLPServer/src/main/resources/rules.properties");
p.load();
prop.addConfiguration(p);
} catch (ConfigurationException e) {
e.printStackTrace();
}
final int processors = prop.getInt("server.processors", 1);
// If you don't see this line - likely config name is wrong
System.out.println("Using processors:" + processors);
}
public void setKeyword(String customerId, String keyword){
}
public void setRegexp(String customerId, String regexp)
{}
}
as you see I'm going to add values to some properties. Here is the .properties file itself:
users = admin, root, guest
users.admin.keywords = admin
users.admin.regexps = test-5, test-7
users.root.keywords = root
users.root.regexps = *
users.guest.keywords = guest
users.guest.regexps =
I have a GUI for user to add keywords and regexps to this config. so, how to implement methods setKeyword and setRegexp?
The easyest way I found is to read the current values of the property to the String[], add there a new value and set property.
props.setProperty(fieldName, values);
What my application is doing is creating a large csv file (its a report) and the idea is to deliver the contents of the csv file without actually saving a file for it. Here's my code
String csvData; //this is the string that contains the csv contents
byte[] csvContents = csvData.getBytes();
response.contentType = "text/csv";
response.headers.put("Content-Disposition", new Header(
"Content-Disposition", "attachment;" + "test.csv"));
response.headers.put("Cache-Control", new Header("Cache-Control",
"max-age=0"));
response.out.write(csvContents);
ok();
The csv files that are being generated are rather large and the error i am getting is
org.jboss.netty.handler.codec.frame.TooLongFrameException: An HTTP line is larger than 4096 bytes.
Whats the best way to overcome this issue?
My tech stack is java 6 with play framework 1.2.5.
Note: the origin of the response object is play.mvc.Controller.response
Please use
ServletOutputStream
like
String csvData; //this is the string that contains the csv contents
byte[] csvContents = csvData.getBytes();
ServletOutputStream sos = response.getOutputStream();
response.setContentType("text/csv");
response.setHeader("Content-Disposition", "attachment; filename=test.csv");
sos.write(csvContents);
We use this to show the results of an action directly in the browser,
window.location='data:text/csv;charset=utf8,' + encodeURIComponent(your-csv-data);
I am not sure about the out of memory error but I would at least try this:
request.format = "csv";
renderBinary(new ByteArrayInputStream(csvContents));
Apparently netty complains that the http-header is too long - maybe it somehow thinks that your file is part of the header, see also
http://lists.jboss.org/pipermail/netty-users/2010-November/003596.html
as nylund states, using renderBinary should do the trick.
We use writeChunk oursleves to output large reports on the fly, like:
Controller:
public static void getReport() {
final Report report = new Report(code, from, to );
try {
while (report.hasMoreData()) {
final String data = await(report.getData());
response.writeChunk(data);
}
} catch (final Exception e) {
final Throwable cause = e.getCause();
if (cause != null && cause.getMessage().contains("HTTP output stream closed")) {
logger.warn(e, "user cancelled download");
} else {
logger.error(e, "error retrieving data");
}
}
}
in report code
public class Report {
public Report(final String code, final Date from, final Date to) {
}
public boolean hasMoreData() {
// find out if there is more data
}
public Future<String> getData() {
final Job<String> queryJob = new Job<String>() {
#Override
public String doJobWithResult() throws Exception {
// grab data (e.g read form db) and return it
return data;
}
};
return queryJob.now();
}
}
I get the following problem when trying to display a list of items. For each item, I have to display an image which is dynamically loaded via a Wicket WebResource. The items are loaded step by step — 50 at a time — upon user scrolling, using an Ajax scroll.
[ERROR] 2011-04-19 09:58:18,000 btpool0-1 org.apache.wicket.RequestCycle.logRuntimeException (host=, request=, site=):
org.apache.wicket.WicketRuntimeException: component documentList:scroller:batchElem:666:content:item:3:batchItemContent:linkToPreview:imageThumbnail not found on page com.webapp.document.pages.DocumentListPage[id = 1]
listener interface = [RequestListenerInterface name=IResourceListener, method=public abstract void org.apache.wicket.IResourceListener.onResourceRequested()]
org.apache.wicket.protocol.http.request.InvalidUrlException: org.apache.wicket.WicketRuntimeException: component documentList:scroller:batchElem:666:content:item:3:batchItemContent:linkToPreview:imageThumbnail
not found on page com.webapp.document.pages.DocumentListPage[id = 1] listener interface = [RequestListenerInterface name=IResourceListener, method=public abstract void org.apache.wicket.IResourceListener.onResourceRequested()]
at org.apache.wicket.protocol.http.WebRequestCycleProcessor.resolve(WebRequestCycleProcessor.java:262)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1310)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1428)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:545)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:479)
at org.apache.wicket.protocol.http.WicketFilter$$EnhancerByGuice$$51619816.CGLIB$doGet$6()
at org.apache.wicket.protocol.http.WicketFilter$$EnhancerByGuice$$51619816$$FastClassByGuice$$6d42bf5d.invoke()
at com.google.inject.internal.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:64)
at com.freiheit.monitoring.PerformanceMonitoringMethodInterceptor.invoke(PerformanceMonitoringMethodInterceptor.java:115)
at com.google.inject.internal.InterceptorStackCallback$InterceptedMethodInvocation.proceed(InterceptorStackCallback.java:64)
at com.google.inject.internal.InterceptorStackCallback.intercept(InterceptorStackCallback.java:44)
at org.apache.wicket.protocol.http.WicketFilter$$EnhancerByGuice$$51619816.doGet()
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:312)
at org.apache.wicket.protocol.http.WicketFilter$$EnhancerByGuice$$51619816.CGLIB$doFilter$4()
How can this problem be solved?
Here is the part of the code responsible for adding the image:
previewLink.add(createThumbnailSmall("imageThumbnail", documentModel));
in
createThumbnailSmall(final String id, final IModel<BaseDocument> documentModel) {
// thumbnailResource is an object that contains the path of the image
if (thumbnailResource != null) {
final WebResource resource = getWebResource(thumbnailResource);
final Image image = new Image(id, resource);
return image;
}
return new InvisibleContainer(id);
}
WebResource getWebResource(final DocumentResource documentResource) {
return new WebResource() {
private static final long serialVersionUID = 1L;
#Override
public IResourceStream getResourceStream() {
return new BaseStreamResource(documentResource);
}
};
}
where BaseStreamResource is the following:
public class BaseStreamResource extends AbstractResourceStream {
private InputStream _fileInputStream = null;
private DocumentResource _resource = null;
public BaseStreamResource(final DocumentResource documentResource) {
_resource = documentResource;
}
#Override
public InputStream getInputStream() throws ResourceStreamNotFoundException {
if (_fileInputStream == null) {
try {
if (_resource == null) {
throw new ResourceStreamNotFoundException("Resource was null");
}
_fileInputStream = _resource.getFileInputStream();
} catch (final ResourceNotAvailableException ex) {
throw new ResourceStreamNotFoundException(ex);
}
}
return _fileInputStream;
}
In HTML:
<a wicket:id="linkToPreview" href="#">
<img wicket:id="imageThumbnail" alt="Attachment"></img></a>
The code added hasn't really added any clues for me, but maybe I can help narrow it down a bit anyway.
The stacktrace includes a reference to com.webapp.document.pages.DocumentListPage, which is likely calling some of the code you've posted. The error indicates a bad url, so debugging into that class, adding debug prints, and looking at the values of any field containing a url might be worthwhile.
It might even help to modify the code in DocumentListPage (maybe temporarily for debugging) to catch org.apache.wicket.protocol.http.request.InvalidUrlException and adding debugging prints specifically when the exception is caught.
This isn't really an answer, but it's too big for a comment, and maybe it'll help you get closer to an answer.
The following solution solved the problem:
- extend WebResource class
- add extended class as a resource to application shared resources
Ex:
public class MyWebResource extends WebResource {
final ValueMap map = new ValueMap();
#Override
public IResourceStream getResourceStream() {
String fileName = getFileName();
File file = new File(basePath, fileName);
if (!file.exists()) {
LOG.error("File does not exist: " + file);
throw new IllegalStateException("File does not exist: " + file);
}
return new FileResourceStream(file);
}
public final void addResource() {
Application.get().getSharedResources().add(getClass().getName(), this);
}
protected String getFileName() {
return getParameters().getString("id");
}
public final String urlFor(final String fileName) {
final ResourceReference resourceReference = new ResourceReference(getClass().getName());
final String encodedValue = WicketURLEncoder.QUERY_INSTANCE.encode(fileName);
map.add("id", encodedValue);
final CharSequence result = RequestCycle.get().urlFor(resourceReference, map);
if (result == null) {
throw new IllegalStateException("The resource was not added! "
+ "In your Application class add the following line:"
+ "MyConcreteResource.INSTANCE.addResource()");
}
String absoluteUrl = RequestUtils.toAbsolutePath(result.toString());
return absoluteUrl;
}
}
In Application class, in init(), I have added MyWebResource to shared resources:
public void init() {
...
new MyWebResource().addResource();
...
}