I have a web page hosted on jetty server. The page displays some static images, the images directory are kept inside a jar, say application.jar. This application.jar is packaged inside a one-jar. I am facing problem in accessing the images directory as they are inside a jar which is inside another jar.
I have tried almost all the ways to get URL of the images directory: class.getClassLoader().getResource(), Thread.currenctThread.getContextClassLoader().getResource(), ClassLoader.getSystemClassLoader().getResource(), etc. None of them is of any help. I wrote all these statements, i.e. tried to get access to the images directory, from a class that is inside the application.jar. This jar contains the images directory too.
If anybody has ever faced this before, please reply to this thread. I am open to any other ideas also that may help me achieve the objective.
You can use
InputStream input = getClass().getResourceAsStream("/classpath/to/my/file");
You can find more here:
How to read a file from jar in Java?
How to access resources in JAR file?
Related
im wring a simple program and my images load in fine in the project but as soon as i export it into a jar file none of them load. i have little to no experiance creating artifacts or jar files.
project structure:
project:
src:
myclass1, myclass2...
res:
image1.png image2.png...
im using Toolkit.getdefaultToolkit to load in images
in my class i am loading the images in the constructor by writing
myImage = toolkit.getImage("res/image1.png");
this works perfectly fine in the project. does not work in the jar
i have also tried
myImage = toolKit.getImage("image1.png");
which does not work in the project or while opening the jar
i know toolkit is not the best way to go about loading images but i would like to know how i can fix this issue while using toolkit.
ive even tried using the absolute path to a folder on my desktop and once again they load in fine in my project but they do not get loaded when opening the jar. please help ive tried everything. thanks
(btw) if i open the jar file in intellij the images load but if i open the jar file in finder or from my desktop they do not. i want to be able to send the finished project to someone
The toolkit.createImage(String) method takes in a string, and interprets it as a path, looking for a file at that path. An entry in a jar file is not itself a file. It is therefore impossible to use this method to read image files that are in a jar.
However, that's not the only createImage method. There's also toolkit.createImage(URL) and that is the one you want.
SomeClass.class.getResource("something.png")
This expression works on any class (Foo.class gets you the class instance for Foo, and all class instances have the getResource method), and will look for the named entry in the exact same place SomeClass.class (the file) lives. If SomeClass.class currently lives in a jar file, then that's where it'll look.
Thus, ensure that img.png is in the same place your class file is (ensure it is jarred along with the rest), and that will work. You can also ask for e.g. SomeClass.class.getResource("/foo/bar/img.png"); this will then look from the 'root' of where SomeClass is. So if you have a jar such that if you run jar tvf thatjar.jar and you get:
....
/com/foo/yourpackage/SomeClass.class
....
/foo/bar/img.png
then /foo/bar/img.png works.
thus: Once you know where you put that stuff in your jar file:
toolkit.createImage(YourClass.class.getResource("image1.png"))
is what you're looking for.
I have tried many variants but I cant find correct.
I have something like
Inside my jar, which created by Maven I can see that
That is my folder with classes. And, by the way, If I start my program in IDEA, not from Console, there is not any exception with paths
Here, I am in debug mode start my jar trying to see, where is the problem.
If I do 'file.exists()' it would be false but file inside. I think, that problem because of '.jar!\' in the path, but I don`t know how to remove that.
Anyway I've tried absolute and relative path, I've tried
Thread.getCurrentThread.getContextLoader.getResource()
GUI.class.getResource()
GUI.class.getClassLoader.getResource()
Nothing help
You can't use File to open resources inside a jar file. File can only be used with normal files and directories.
Note: using File works fine within in the IDE, since all files are not packaged in a jar file yet. But the program will break after you package it.
Once you locate the resource eg. URL res = GUI.class.getResource("/rxtx64/myres.dll") , you can open that resource as a stream InputStream is = res.openStream(); .
See also related answers Utils to read resource text file to String (Java) and How to read a text-file resource into Java unit test?
I'm developing a simple mail sender as Java EE application.
The project structure is shown as follows:
To properly setup email contents, I need to read the *.vm files placed inside the resource folder, that I supposed to have as path classpath:/templates/mail/*.vm (as with Spring)... But my supposition is wrong!
Which is the right path to use?
Should I have to use the META-INF folder? Is this solution more
java-ee-compliant? In that case, where have I to put the META-INF folder inside my project structure?
Update:
I packaged the project as .war, then I putted the files in:
/src/main/webapp/WEB-INF/classes/templates/mail/
Then:
org.apache.velocity.Template t = myVelocityEngine.getTemplate("classpath:/templates/mail/account_to_confirm.vm",
"UTF-8");
Nonetheless, the app returns an error at runtime:
Unable to find resource 'classpath:/templates/mail/account_to_confirm.vm'
What am I doing wrong?
Just to better understand:
Supposing that I'd like to deploy this app as jar (removing the servlet class, of course): in that case, should I have to edit the folder layout in order to still use the same path into the source code?
I think the problem is due to the prefix classpath:: where did you find that you have to use it?
You might find useful understanding how to initialize VelocityEngine reading Loading velocity template inside a jar file and how Configuring Resource Loaders in Velocity.
If you can, use Classloader.getResourceAsStream("templates/mail/*.vm"); or similar getResourceAsURL method.
If not, take a look at where files from resources are placed inside WAR. In your case, the file should be in /WEB-INF/classes/templates/mail .
I'm trying to read from a text file in Netbeans. In the top level of my project directory I have foo.txt. Then in my code I have:
File file = new File("foo.txt");
It throws a FileNotFoundException, however. It's a Java web application using Spring and Tomcat, but I'm not sure if those details matter since I'm running the whole thing inside Netbeans. Basically, I just want to know where I need to put the file so Netbeans will read it.
Update - good call guys, it's looking in Tomcat's bin directory. Now this may be a stupid question but, how would I go about getting it to look in my top level project directory? I feel like dropping text files into tomcat's bin would be innapropriate.
You can try printing the absolute path of the File object to see where it is looking on the filesystem.
System.out.println(file.getAbsolutePath());
I would use the following to figure out where to put the file:
System.out.println(System.getProperty("user.dir"));
To directly answer your question, If you're running an application on Tomcat, files will be opened from the current working directory. That will likely be the bin/ folder in your tomcat directory.
You can find out for sure where your program is looking by examining the result of file.getAbsolutePath().
However, for web applications, I would suggest putting files you need to read in your classpath so you don't have to depend on a certain file structure when you deploy your web application.
try System.getProperty("user.dir") to get current working directory
I used following code to access an image from "res" folder with NetBeans
imgWelcome = Image.createImage("/cover.png");
img = new ImageItem(null, imgWelcome, ImageItem.LAYOUT_CENTER, "");
Though the resource is not getting detected and i keep on getting NullPointerException. As weird as it sounds, exactly same technique worked in my previous program.
What am I doing wrong here?
P.S. I've double checked that the file exists in the res folder
There might be many reasons for this, but I have found that most of the time, it is due to how the project is built. Some build scripts include the resources in the res/ folder as top-level files, and some include that folder as a folder in the jar file.
What I have always done to troubleshoot is to rename the jar output to zip and look inside. If the image files are contained in a folder then you should address them as such.
Your code will not find cover.png if it is in the /res folder.
Inspect the contents of your jar using 7-Zip or similar, ensure the image really is in the /res folder, then replace the first line with imgWelcome = Image.createImage("/res/cover.png");.
Oh wow.. this was because .png was not supported by my emulator. And what all I tried :(