I have no trouble reading files of different types using GDAL's Java bindings (version 2.2.1) via the org.gdal.ogr.ogr.OpenShared(filePath) method to create a DataSource. If I want to create a SQLite file from a DataSource, however, how would I do it?
Looking in the JavaDocs, I've found some ExportTo methods on the Geometry object that you can use to manually build GeoJSON, WKT, KML and others: http://gdal.org/java/org/gdal/ogr/Geometry.html
There doesn't seem to be anything in the Driver class that would let you use them to export a DataSource however.
Using ogr2ogr it would be as simple as running the following:
ogr2ogr -f "SQLite" ./output.sqlite3 ./input.geojson
And there is this technique for running ogr2ogr from within Java, but I would have assumed there'd be something native in the Java bindings.
I've accepted that the best way to do this is to simply include the ogr2ogr.java file from the GitHub repo in my project and wrap it in a function that makes it cleaner to access. It is almost a direct port of the original C++ GDAL file.
The one change I made was to rename the ogr2ogr main function to execute so that it didn't confuse application when I ran it.
Related
I'm aware of all the other questions about this topic, but I haven't found a good solution for my problem. Currently I am trying to use Java code in my C# project. I've already tried to convert the JAR files into .DLL files with IKVM, but this didn't work for me because the JAR files are to complicated to translate into C# because not every component, which were used in Java, can be found in C#. The normal call of the JAR file doesn't work for me either because I need to work with the class instances of the declared classes in the Java code.
Back to my question: Does anybody know how I could use Java code in my project? I've heard that it may be possible to implement Java code like it would be native, is that true? Note that I've to work with the class instances of the classes declared in the Java code.
I highly appreciate any kind of help, sheers!
Edit:
My work around would be that I include batch files, which are calling the JAR files. I will include these batch files into my C# Project and work with the batch files. This may be a even better approach for me because every input and output of the JAR files are done via XML files.
This kind of mixup are not generally a good approach. I think the .Net Framework is very mature and you can find everything you want to do your work.
I would suggest you the following approach :
You can wrap your Java library in a REST API and call it in your C# code. Your REST API can be hosted on an external server or use an embedded server or even a spring boot project.
You can read this post for more details.
I would like to build a centOS 7 instance on AWS and install Apache to build web server.
After that, I would like to modify the config file, /etc/hosts and /etc/httpd/conf.d/test.conf where test.conf is created by me.
Can I use java to modify the file directly? Or I should create the file and replace the old file on instance? I am little bit confused for the feasibility. Please someone help.
There seem to be a few questions here, so I've split them out.
Q: Can I use programming language X to modify a file on the local filesystem?
A: Yes, with very few exceptions. For Java, yes (if the instance has a JRE).
Q: Should I use Java?
A: Probably not the first choice (you could probably do what you need in a shell script at launch).
Q: Should I create the Apache config files dynamically or build them into an AMI?
A: Difficult to answer without more information. There are pros and cons to AMIs. If it's simple and quick to create/modify the files on launch, then I'd do it that way.
DevOps is a big subject and there are many options available to you for bootstrapping EC2 instances. Pre-baked AMIs is one option. Another simple option that you might consider is to write userdata scripts, that run at launch time, and that set up the instance for you (see simple nginx example). They can install software, modify config files, start services, and other things. They can also pull collateral such as pre-staged config files from S3, which can be a handy option.
I'm trying to read a .qm translation files with Java.
.qm files are binary files. I don't have access to the .ts files.
And I don't find much info on these .qm files.
How are they structured ?
Regards,
There's no documentation that I know of, but if you look at QTranslator::load you should be able to follow the format of the QM file.
You will probably need to reimplement QTranslator in Java, as you need not only the ability to load the files, but also to extract and apply translations in Qt fashion.
As per request of OP:
You could use those files by using the Qt libraries and JNI. By using the translator in a c++ dll you can translate strings easily. However, you cannot extract the files or list the contained translations. But if all you need is the actual translation, this solution should work.
I cannot give a real example, because I only now how it works in theory, I haven't tried it, because it's not trivial. But if you are eager to try it out, the general idea would be:
Create a C++ dll and build it against QtCore. The easiest way is to download Qt from their website qt.io. You can for example create a default library project with QtCreator. Note: Besides Qt5Core.dll, Qt requires other libraries to correctly run. They are all included in the installation, but once you deploy your application, those of course have to be includes as well.
Include JNI to the C++ project and link against it. if you're new to this, here is a nice tutorial: Java Programming Tutorial
Create your wrapper methods. Methods in cpp you can call from java that take java strings, convert them to QString, translate them with QTranslator and convert them back.
Load the library in Java and execute those methods
Important:
First, I don't know how java handles dll dependencies. If you encounter errors while loading the dll, it's probably because dependencies of your dll are not present. Second, Qt typically requires a QCoreApplication running in the main thread for most of it's operations. I tested the translator without such an app, and it worked. So apparently for translations only the app is not required. However, depending on what you do in your dll, I think this is important to know.
If you need more details, feel free to ask.
I have a java application(runnable jar) and VB scripts which I'm using to telnet to a remote machine and executing some cmds. So, I first execute the vbs files and then run my jar(in all everything is working fine).
But, now I want to integrate scripts and my java jar such that, running the jar should first trigger the script followed by Java related task.
Few thing which I've come across are -
I cannot trigger Vbs from Java(javax.script - correct me if I'm wrong). So, possible options to rewite the script in are -
Javascript(have no idea what my Javascript file would have so that after reading it inside java class I can write it to the Socket output stream.)
PHP(I tried this using Java bridge but it gives some error saying cgi needs to installed. And, I believe it also requires PHP to be installed on the host machine before executing my jar. So I'm not going any futher with this approach.)
Long story short, I don't want to create any dependencies - I am looking for something like where I can package any external lib with my jar(if required) and use it to execute my scripts.
You can execute the VB-Script in an external command. There are a lot of resources on the internet that explain how to do that - for instance this link also explains how to start a VB-Script from within java. However I do not know if you need the output from the script within the Java. If so you'll have to listen to the outputstream of the created process. You should find an example for that as well with that link (using the processbuilder)
If you have the script packaged within your jar, I fear you'll have to unpack it to a temporary folder and execute it there.
The closest I have seen about VB script as a JVM language is in answer here.
Visual Basic or VBScript as Java Scripting Engine
Have you seen this wikipedia entry about JVM languages?
http://en.wikipedia.org/wiki/List_of_JVM_languages
Also, have you considered using Ant and using it programmatically from java?
Another option is to use groovy/Ant from Java.
I am currently writing a program in JAVA that examines the behavior of external executable. One of the requirements is to observe the file operations of the external executable in real time (check if the executable creates/ deletes/modifies any file). I tried to find a suitable API in java to help me do this though it was not possible to find one. I have found the Class FileAlterationObserver which is not suitable for my program since you have to specify manually all the directories you want to monitor.
I was wondering if any of you knows a good API to use?
Thanks for your time in advance.
Without java, you could use the linux lsof command to list the open files in the system. Alternatively, and with Java, you can use libnotify, but you will need to specify the folders. I can't see any other way of doing this with pure java.
EDIT #Keppil linked you to the file change notification API that looks way more suitable than libjnotify. I wasn't aware it existed!