java.net.URL refer to a file in a parent directoty - java

I have a very basic question. I need a URL object but the file is in the previous directory relative to the project.
For instance, if I do
File testFile = new File("../../data/myData.xml");
works perfectly fine, it finds the file
However,
URL testURL = new URL("file:///../../data/myData.xml")
gives an
Exception in thread "main" java.io.FileNotFoundException: /../../data/myData.xml
Any idea, how to solve, work around this? without changing the position of the data?
Thanks a lot in advance
Altober

you can use this
URL testURL = new File("../../data/myData.xml").toURI().toURL();

/**
* #param args
*/
public static void main(String[] args) {
try {
URL testUrl = new URL("file://C:/Users/myName/Desktop/abc.txt");
System.out.println(testUrl.toString());
} catch (MalformedURLException e) {
e.printStackTrace();
}
}
}
The above code is working file, just tested it, so you need to use file:// and if possible try full path

Exception in thread "main" java.io.FileNotFoundException: /../../data/myData.xml
Note that it is looking for parent directory of root directory, not of current directory.
I dont know if File URLs can refer to relative paths, try
‘new URL("file://../../data/myData.xml")'‘

Related

Load a file from a specific directory

I have a specified URL that i cant change i.e.
/opt/local/java/config/npvr.properties
where should i place my file so that the following code can work:
String PROPERTIESFILEPATH1 = "/opt/local/java/config/npvr.properties";
File tmPropertiesFile = new File(PROPERTIESFILEPATH);
Properties properties = new Properties();
if (tmPropertiesFile.exists()) {
.....
}
i have tried placing my file in directory shown below but it didn't work:
My problem is that I can change only the location of property-file without changing the code to solve this problem. Please Help.
The file needs to go in /opt/local/java/config, not [projectdir]/opt/local/java/config. You are putting it in the wrong place
If you are using linux then add this file /opt/local/java/config/ directory location outside of your project.
"OR"
in windows C:\opt\local\java\config\ here.
use getClass().getResourceAsStream to load property file from relative of class
public class Main {
public static void main(String args[]) throws Exception{
String PROPERTIESFILEPATH = "/opt/local/java/config/npvr.properties";
//File tmPropertiesFile = new File(PROPERTIESFILEPATH);
Properties properties = new Properties();
InputStream ins=null;
//ins=new FileInputStream(PROPERTIESFILEPATH);
ins=new Main().getClass().getResourceAsStream(PROPERTIESFILEPATH);
properties.load(ins);
System.out.println(properties.get("Hello"));
}
}

Crawling GitHub with JGit

I'm trying to crawl a GitHub Wiki with JGit.
When I try it with one URL, it worked perfectly fine. Then I tried it with another random URL and got an error.
Please see the extract of my code:
import java.io.File;
import java.io.IOException;
import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.api.errors.GitAPIException;
public class Main {
// with this URL I get an error
String url = "https://github.com/radiant/radiant.wiki.git";
// this URL works
// String url = "https://github.com/WardCunningham/Smallest-Federated-Wiki.wiki.git";
public static void main(String[] args) {
Main m = new Main();
m.jgitTest();
System.out.println("Done!");
}
public void jgitTest() {
try {
File localPath = File.createTempFile("TestGitRepository", "");
localPath.delete();
Git.cloneRepository().setURI(url).setDirectory(localPath).call();
} catch (IOException | GitAPIException e) {
System.err.println("excepton: " + e.getMessage());
e.printStackTrace();
}
}
}
This is the stack trace:
Exception in thread "main" org.eclipse.jgit.dircache.InvalidPathException: Invalid path (contains separator ':'): How-To:-Create-an-Extension.textile
at org.eclipse.jgit.dircache.DirCacheCheckout.checkValidPathSegment(DirCacheCheckout.java:1243)
at org.eclipse.jgit.dircache.DirCacheCheckout.checkValidPathSegment(DirCacheCheckout.java:1225)
at org.eclipse.jgit.dircache.DirCacheCheckout.checkValidPath(DirCacheCheckout.java:1185)
at org.eclipse.jgit.dircache.DirCacheCheckout.processEntry(DirCacheCheckout.java:311)
at org.eclipse.jgit.dircache.DirCacheCheckout.prescanOneTree(DirCacheCheckout.java:290)
at org.eclipse.jgit.dircache.DirCacheCheckout.doCheckout(DirCacheCheckout.java:408)
at org.eclipse.jgit.dircache.DirCacheCheckout.checkout(DirCacheCheckout.java:393)
at org.eclipse.jgit.api.CloneCommand.checkout(CloneCommand.java:236)
at org.eclipse.jgit.api.CloneCommand.call(CloneCommand.java:127)
at Main.jgitTest(Main.java:21)
at Main.main(Main.java:13)
If you visit the wiki page of the URL that doesn't work (https://github.com/radiant/radiant/wiki), you will find this page: How To: Create an Extension.
The title of this page is the cause of the error: Invalid path (contains separator ':'): How-To:-Create-an-Extension.textile.
I assume I need to escape all output.
I suppose you are on windows. You can't create a file on windows having the ":" in the name. JGit should handle it somehow, so I suppose this is a bug in JGit.
I had the same problem with pure git, and this answer helped me:
git config core.protectNTFS false

Extracting Text From JPG

I've tried this code and added the needed jar files but still I'm getting an error message like Exception in thread "main" java.lang.UnsatisfiedLinkError: Unable to load library 'libtesseract302'.
Is there a complete tutorial how to extract text and what things should be done to address the error? Any help is appreciated...
import net.sourceforge.tess4j.*;
import java.io.File;
public class ExtractTxtFromImg {
public static void main(String[] args) {
File imgFile = new File("C:\\Documents and Settings\\rueca\\Desktop\\sampleImg.jpg");
Tesseract instance = Tesseract.getInstance(); // JNA Interface Mapping
// Tesseract1 instance = new Tesseract1(); // JNA Direct Mapping
try {
String result = instance.doOCR(imgFile);
System.out.println(result);
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
}
In addition to adding the jars, you also need to add the natives. You can do so with Djava.library.path="C:\[absolute path to dir containing *.dll files and such]"
Note that you need to provide the directory, not the file itself.

getClass().getResource() in static context

I'm trying to get a resource (image.png, in the same package as this code) from a static method using this code:
import java.net.*;
public class StaticResource {
public static void main(String[] args) {
URL u = StaticResource.class.getClass().getResource("image.png");
System.out.println(u);
}
}
The output is just 'null'
I've also tried StaticResource.class.getClass().getClassLoader().getResource("image.png");
, it throws a NullPointerException
I've seen other solutions where this works, what am I doing wrong?
Remove the ".getClass()" part.
Just use
URL u = StaticResource.class.getResource("image.png");
Always try to place the resources outside the JAVA code to make it more manageable and reusable by other package's class.
You can try any one
// Read from same package
URL url = StaticResource.class.getResource("c.png");
// Read from same package
InputStream in = StaticResource.class.getResourceAsStream("c.png");
// Read from absolute path
File file = new File("E:/SOFTWARE/TrainPIS/res/drawable/c.png");
// Read from images folder parallel to src in your project
File file = new File("images/c.jpg");
// Read from src/images folder
URL url = StaticResource.class.getResource("/images/c.png")
// Read from src/images folder
InputStream in = StaticResource.class.getResourceAsStream("/images/c.png")

Java: opening a resource (txt file) which is in a jar with OS standard application

i get the error "AWT-EventQueue-0 java.lang.IllegalArgumentException: URI is not hierarchical".
-I'm trying to use the java.awt.Desktop api to open a text file with the OS's default application.
-The application i'm running is launched from the autorunning jar.
I understand that getting a "file from a file" is not the correct way and that it's called resource. I still can't open it and can't figure out how to do this.
open(new File((this.getClass().getResource("prova.txt")).toURI()));
Is there a way to open the resource with the standard os application from my application?
Thx :)
You'd have to extract the file from the Jar to the temp folder and open that temporary file, much like you would do with files in a Zip-file (which a Jar basically is).
You do not have to extract file to /tmp folder. You can read it directly using `getClass().getResourceAsStream()'. But note that path depend on where your txt file is and what's your class' package. If your txt file is packaged in root of jar use '"/prova.txt"'. (pay attention on leading slash).
I don't think you can open it with external applications. As far as i know, all installers extract their compressed content to a temp location and delete them afterwards.
But you can do it inside your Java code with Class.getResource(String name)
http://download.oracle.com/javase/6/docs/api/java/lang/Class.html#getResource(java.lang.String)
Wrong
open(new File((this.getClass().getResource("prova.txt")).toURI()));
Right
/**
Do you accept the License Agreement of XYZ app.?
*/
import java.awt.Dimension;
import javax.swing.*;
import java.net.URL;
import java.io.File;
import java.io.IOException;
class ShowThyself {
public static void main(String[] args) throws Exception {
// get an URL to a document..
File file = new File("ShowThyself.java");
final URL url = file.toURI().toURL();
// ..then do this
SwingUtilities.invokeLater( new Runnable() {
public void run() {
JEditorPane license = new JEditorPane();
try {
license.setPage(url);
JScrollPane licenseScroll = new JScrollPane(license);
licenseScroll.setPreferredSize(new Dimension(305,90));
int result = JOptionPane.showConfirmDialog(
null,
licenseScroll,
"EULA",
JOptionPane.OK_CANCEL_OPTION);
if (result==JOptionPane.OK_OPTION) {
System.out.println("Install!");
} else {
System.out.println("Maybe later..");
}
} catch(IOException ioe) {
JOptionPane.showMessageDialog(
null,
"Could not read license!");
}
}
});
}
}
There is JarFile and JarEntry classes from JDK. This allows to load a file from JarFile.
JarFile jarFile = new JarFile("jar_file_Name");
JarEntry entry = jarFile.getJarEntry("resource_file_Name_inside_jar");
InputStream stream = jarFile.getInputStream(entry); // this input stream can be used for specific need
If what you're passing to can accept a java.net.URLthis will work:
this.getClass().getResource("prova.txt")).toURI().toURL()

Categories

Resources