how do I check if openCv is already loaded? - java

i have this line code in my java program to load openCV
static {
nu.pattern.OpenCV.loadShared();
}
When I first deploy to tomcat hosted on linux server it works fine. But on subsequent redeploys, I get an error message saying the library has already been loaded. I have to shutdown and startup tomcat again to get it to work.
What should I do in this situation?

Related

IntelliJ is not running Spring Boot Debugger

I am trying to debug a Spring boot project with IntelliJ. Suddenly, my lines do not debug after working for last few years.
It will debug through the class, but when i try to run a method, it will not see the breakpoint. I got an application context message earlier, which I fixed, but its still not working. https://www.jetbrains.com/help/idea/2021.2/spring-support.html#spring-file-set
It will see/execute these lines in the background (like its one another thread), but not will debug/catch the method lines.
#Autowired
public EncounterFacade(SuperbillRepository superbillRepository, EncounterRepository encounterRepository) {
this.superbillRepository = superbillRepository;
this.encounterRepository = encounterRepository;
}
Currently using a Mac system. It was already running Local host port in the background,
Ran npx kill-port 8080 to resolve the issue and it worked.

Elastic Beanstalk fails creating

I finally reached the point where my Elastic Beanstalk Instance / Environment got launched. (Java Corretto 11 Platform) Now it fails starting up the provided .jar file.
In the eb-engine.log file, I am not able to find any more error than this:
2021/05/27 11:36:25.889735 [INFO] Executing instruction: StageJavaApplication
2021/05/27 11:36:25.889871 [ERROR] An error occurred during execution of command [app-deploy] - [StageJavaApplication]. Stop running the command. Error: staging java app failed due to invalid zip file
The jar file is a Spring Boot application built with mvn -B package.
Locally the whole thing starts, but crashes afterwards because of not given environment variables (Expected behaviour).
But it seems AWS is not even starting the application..
Any suggestions on this?
Spring Boot apps run nicely on Elastic Beanstalk. However, you do need to set some variables. For example, have you set server-port variable to 5000?
And as you stated, to successfully use a Service Client, you can set environment variables for your creds. Here is an end to end walkthrough that shows how to successfully put a Spring BOOT app that invokes several AWS Services on Elastic Beanstalk.
Creating your first AWS Java web application
PS - your log file mentions a ZIP file. Be sure to create the JAR properly as discussed in the above example.
Just in case someone arrive here looking for an answer about this guy:
Error: staging java app failed due to invalid zip file
I was renaming my service jar in Gradle, using:
tasks.withType<org.springframework.boot.gradle.tasks.bundling.BootJar> {
archiveFileName.set("service.jar")
launchScript()
}
And ElasticBeanstalk was not happy about the renaming.
When I let it have the default name, then no zip issues and all worked like a charm.

play application startup isses with VM variable -Dprecopiled=true?

I'm using play1-1.3.0. In production mode, I'm starting up my application, by using this command play start MyApp -Dprecompiled=true i got this error message in logs.
play:424 - Precompiled classes are missing!!
I exactly don't know why I'm getting this error message.
You need to of ran play precompile first this will compile classes ready to use

UnsatisfiedLinkError and NoClassDefFoundError : Running Java Mapscript on Ubuntu 11.10

We have coded and run a dynamic web application using MAPSERVER(Version 6.0.1) on windows platform using Java Technology. Now, there is need of deploying it on Ubuntu 11.10. We have installed Apache Tomcat 6.0, Mapserver 6.0.1, Apache 2.0, and FWTools-2.0.1(As this package contain all required tools for mapserver if I am not wrong, so I didn't feel any other tools to be installed). We have deployed the war file(and put application without) in Apache Tomcat 's Webapps folder. I even got the index page which dont have code related with mapscript api. But while fetching the other servlet with mapscript we are getting following error...
java.lang.UnsatisfiedLinkError: no mapscript in java.library.path
java.lang.ClassLoader.loadLibrary(ClassLoader.java:1681)
java.lang.Runtime.loadLibrary0(Runtime.java:840)
java.lang.System.loadLibrary(System.java:1047)
edu.umn.gis.mapscript.mapscriptJNI.<clinit>(mapscriptJNI.java:23)
edu.umn.gis.mapscript.mapObj.<init>(mapObj.java:283)
Again while refreshing the browser page where the above error was displayed, I got a change,
java.lang.NoClassDefFoundError: Could not initialize class
edu.umn.gis.mapscript.mapscriptJNI
edu.umn.gis.mapscript.mapObj.<init>(mapObj.java:283)
I searched on net about the above problem. But finally blank. Please, provide idea about the above problem.
I'm not going to explain why you're getting the UnsatisfiedLinkError, but instead I'll explain why you are getting the NoClassDefFoundError when you reload the page.
A NoClassDefFoundError with a message Could not initialize class ... is thrown by the JVM when it attempts to initialize a class that it has already tried and failed to initialize.
The first of your two stacktraces contains the line
edu.umn.gis.mapscript.mapscriptJNI.<clinit>(mapscriptJNI.java:23)
The method name <clinit> denotes the static initializer, of the class mapscriptJNI. So, at the point that the UnsatisfiedLinkError was thrown, the JVM was trying to initialize this class. Looking at the error message, it seems that this static initializer tried to load the native code library mapscript but failed.
This UnsatisfiedLinkError causes the mapscriptJNI class to fail to initialize successfully. The JVM keeps a record of all classes that fail to initialize, and if you attempt to initialize one of those classes again, you'll get a NoClassDefFoundError with a message saying that it could not initialize that class.
When you refresh the page, you end up causing the JVM to attempt to initialize the class mapscriptJNI a second time. Of course, this class failed to initialize the previous time. Your second stacktrace contains exactly the error I've described.
In short, the UnsatisfiedLinkError is the real error here. Fix that and the other one will go away.
I would check the following 2 items:
Is the mapscript.jar file on Tomcat or at least your webapp's classpath? (NoClassDefFoundError is your big clue here)
Is the libmapscript.so on either your LD_LIBRARY_PATH or -Djava.library.path? (UnsatisfiedLinkError since the shared object cannot be found)
Try having a look at this post, near the Running Java Mapscript (on Linux) section.
Hope that helps!

Using Java Within PHP - Class Not Found

I'm using Tomcat and PHP5 with JavaBridge. I have bridged PHP and Java so I can screencap web pages within PHP. This was working on another server but after moving to a new server I can not get it working, so I'm reaching for straws here.
require_once("http://localhost:8080/JavaBridge/java/Java.inc");
java_autoload("/web/sites/madfrog/domain.com/cron/bin/html2image.jar");
$JavaHTML2Image = new Java("com.elance.proposal.html2image.client.MainBridge");
It should have loaded all of the project html2image.jar when the script _autoloaded it, however when you create the new Java object I get the error
Class Not Found: Fatal error: Uncaught [[o:Exception]:"java.lang.Exception: CreateInstance failed: new com.elance.proposal.html2image.client.MainBridge. Cause: java.lang.ClassNotFoundException: com.elance.proposal.html2image.client.MainBridge
I asked the guys over in Java and they said I needed to put the jar file in the lib so Java could find it, so I dumped it into Tomcat's webapps folder an into /usr/share/java. But that did nothing. With that said the PHP has a direct reference to it, so it should be loaded.
I'm at a lost after two days. any help is appreciated!
Which version of Tomcat do you use?
For Tomcat 6 or Tomcat 7 put the jar either in ${tomcat.home}/lib or in ${tomcat.home}/webapps/${your.war}/lib
While tomcat.home is your tomcat installation directory. And your.war is the name of your war file.

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