Develop Reference

Deployed spring boot jar file to Docker - how to access and change static resources

I'm kinda new to spring and web development as a whole.
My question is:
When you build a spring boot project (using Maven) into jar file and deploy it via Docker, everything is in one jar file. How can you access your resources (css, js, images, html...) if you want to edit something? Like change something in css file or add something to html page. Is it even possible? Or do you have to build a new jar file everytime, when you need to change something (in frontend)? Also, when there are being uploaded some images or other files, where are they stored? This stuff is very confusing for me and i can't find any related books or help at all.
Thanks for help!

when you package any java program it is nothing but a zip file. Based on what kind of package it is, you wither name it as a Jar or War.
Jar == Java archive
War == Web archive
Now, given the fact that jar and war both are essentially a zip archive, it gives you flexibility to extract and modify them just like any other zip file.
On windows, I think softwares like 7zip let you update the jar inline. I have done it multiple times, especially when I wanted to change application.properties alone on cloud machines, and no other code changes were required. In such cases, building the whole jar and transferring it again to cloud machine could be time consuming. So I would just extract the contents, update whatever I want to, and rezip the package.
Here is the commands you can use -
jar xf jar-file
This should extract the files into a directory.
This SO thread will guide you towards creating jar files.
Something like jar cf myJar.jar ** should be enough to generate a jar file IMO, but syntax might vary.

The jar file is actually just a zip file containing all the files and classes of your application, so technically you can change files in it like any other zip archive. Best practice is to build the jar file using Maven or Gradle from source every time you need something changed.
It's good practice to keep the source in version control using Git, and tag each build in the git repository - that way you can easily keep track of changes to the jar file by looking at what's in git at the time of the build.

Where to add log4j configuration file in our project?

I have implemented log4j in my web application project. Project is done using net beans,using tomcat 7.0.41. At first,I created log4j.property file and placed under web page->Web-INF->classes->log4j.properties in net beans and it asks me to locate the file in my project,so I manually located that file to implement log4j in my application. After that I changed the place of the log4j.properties file to myproject->build->web->WEB_INF->classes->log4j.properties in location of my project saved, now its working fine, it did not ask me to manually locate the property file, It takes automatically when my class files executed. Now my problem is that once I committed the project and again checkout the project on some day, property file does not appear and it again ask for property file. So where can I create the log4j property file in my project so that my team mates can utilize it when they checkout project in their system.

Normally you put log4j.properties to src/main/resources/ and it will be copied to the right place by the build process.

I never use net beans, but I think put log4j.properties under Classpath will work.

Not sure how Net Beans handels this, but i think that the "build" directory is where the "compiled" project is put to.
So i would not recommend to put any files there which should be versioned because mostly those directories are ignored for versioning ( see .gitignore files for example when using git).
Resources like property files should be within the sources and your IDE should copy them to the correct place when building the project.

Put and Use .properties file outside Jar

I'm developing a Java Application in Netbeans. The application uses a .properties file (Properties class). The problem is that Netbeans insert this properties file into final .jar file.
How can I make Netbeans not to do this and put the properties file out of jar file?
In this case, how can I use the properties file in code?

Look at the source directories that NetBeans is asked to insert into the JAR and remove the .properties from the list.
You can always read the .properties file by reading it as an InputStream, as long as it's in the CLASSPATH.
The question is: Why do you feel the need to move it out of that JAR? At least it's in the CLASSPATH that way. You seem to be acting against your own best interests here.

when you export project by jar formart from Eclipse IDE, you can config it do not import file .properties into jar file.
If you want use .properties file in the same folder with file jar, you can get current path with code:
String path = <NameClass>.class.getProtectionDomain().getCodeSource().getLocation().getPath();
and now, you can load file .properties from above path.
Good luck to you!

Add resources into a jar upon building

I want to add DLL's, images, textfiles etc to my project as resources so when I export it, the jar contains the resources so they can be used. I am using eclipse.
Problem is I have no idea how to add it. I've tried adding DLLs/pics to the src folder in the project, but when I export the jar, it is not located there
I've looked at How to make a JAR file that includes DLL files? but it only explains how to extract it, not how to add it to the project and build.
EDIT: I am using an applet to open the jar by the way, sorry for missing it!
Cheers

How are you opening the file in java?
Class.getResourceAsStream(name)?
If you are packaging the code in a jar, then you need to use that command. (as opposed to new File(name), which will get the file in the same directory as your jar)
If the file is not physically in your jar, you can check by changing .jar to .zip and extracting it, then check out this doc http://docs.oracle.com/javase/1.5.0/docs/tooldocs/windows/javac.html

Usually in an eclipse project, the src folder is the wrong place to put non-sourcecode-content.
You should try moving to maven as your build system, as it is highly customizable and provides you with folders inside your project for exactly that purpose. (src/main/resources)

Is it possible in Java read files placed in a Jar that it's placed in a Ear too?

I was wondering if is possible to find the content in an XML file placed in a jar thath is placed in a ear too. It would help me find the properties of java beans.
Up into the ear I can iterate through documents and see what's inside, but if it is a jar I can't iterate documents inside that.
Someone can give me some advice?

From the ear file you should be able to extract the jar file. Then you can use WinZip, 7 Zip, etc to do explore the jar file contents the GUI. Or you can run the jar tf command to extract the content of the jar file in command line. If you don't have any of these tools and using windows, then you can rename the jar file to a .zip and windows should be able to explore it (most of the cases it works).
Edits - I am not sure if you wanted to do it using Java. In that case you are looking for JarFile. I found an example of it here for exploring Jar contents programatically.

so i just tested the thing you want to do - and as long as the JAR lies in the classpath of your EAR, then you can access any file within it. basically the try to look up the file from the context-root of your application.
for example if in your JAR the file abc.xml resides under the package a.b.resources, then from say a servlet in your EAR you can access it using :
InputStream is = this.getClass().getClassLoader().getResourceAsStream("a/b/resources/abc.properties");

Yes, you can read any file that is packed into zip file. It does not matter how many nested zip file you have to open on your way. Use ZipInputStream, get needed ZipEntry, read it content. If it is still zip, open it and do it again and again until you access the required resource.