Say i have a java project setup in eclipse. i have all the thirdparty jar's and reading the resources etc set in the eclipse IDE.
ie all the classpath etc are set through the IDE
Now if i want to launch my app from commandline.
Can i get some hints/ links where i can undersand the configuration settings that can be done in Unix / windows machine to launch the application.
Looking for runtime configuration settings.
Because in production environment there is no IDE involved?
Also How do i set classpath in the server say jboss?
You can include the classpath and dependencies info in the Manifest of your application.
And in addition, you can consider ant if you want to be able to build your project on a machine without an IDE at all.
Is there any information that you specify in Eclipse and you need to use in your production env?
Use Eclipse 3.5
Create a launch configuration by selecting your class containing the main method, and running it.
File -> Export -> Java -> Runnable Jar
Personally I like the "put libraries in a sub-folder" since that does not merge jars or use a custom classloader.
The generated jar file can be executed with "java -jar whatever.jar".
You can redo this easier by either generating an ant script or making the launch configuration a shared file.
(Run -> Run configurations. Select launch configuration, Choose "Common" pane. Choose "Shared file" and select a place to put it.
Related
I have a feature based E4 application that I'd like to export as an executable project (.exe since I'm under windows).
I'm following the automated procedure called "Export Project Wizard" but despite I'm getting a .exe file + some JAR's in the same export folder, when I run it I get this error message: "org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError com/test/test1"
com.test.test1 is an external plugin which I included in the depedency tab, and it seems that Eclipse won't find it.
How can I work it out? Should it not automatically export all the required plugins?
I also tried to export that plugin manually, as JAR, but it didn't work.
Thanks
Use 'Export > Plug-in Development > Eclipse product'. This will require you to specify the xxx.product file that was created when you created your e4 application.
You can also launch the same wizard from the xxx.product editor by clicking 'Use the Eclipse product export wizard'.
You must configure your xxx.product file to specify all the features that you are using - your own features and the standard Eclipse features (on the Dependencies tab). For example on my product I have:
my feature
org.eclipse.e4.rcp
org.eclipse.emf.common
org.eclipse.emf.ecore
the 3 Eclipse features are the minimum needed for an e4 application.
Your feature must list all your plugins in its feature.xml plus any dependencies that are not covered in any other feature. Every plugin you want to use must appear in one of the features.
I am trying to connect to mysql database using java on windows7. In spite of adding the complete url of jdbcdriver jar file in CLASSPATH, java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
is thrown. Could anyone tell me what i am missing here? It works if I add the jar file in project library but I want to do it by CLASSPATH itself.
My classpath looks like this-
C:\jython2.5.1\javalib\mysql-connector-java-5.1.12-bin.jar
I want to make it clear that this is not the actual project i am working on. I am actually using Django with Jython, which requires the JDBC driver to access the database. That is the reason why I have to do it using CLASSPATH only.
The CLASSPATH environment variable is only used by the java.exe command and even then only when used without any of the -cp, -classpath, -jar arguments. It is ignored by IDEs like Eclipse, Netbeans and IDEA.
That environment variable is in real world also considered a poor practice since it breaks portability. I.e. program X will run successfully while program Y won't run without altering the CLASSPATH. It's only "useful" for Sun Oracle to prevent that starters get tired of typing the same classpath again and again in the -cp or -classpath arguments when following Java tutorials. In real world, batch/shell files are preferred where just the entire command with -cp/-classpath argument is specified.
In your case you're using an IDE. The classpath is there called the "Build Path". In plain Java projects, it represents both the compiletime and runtime classpath. You can configure it in the project's properties. You can add a complete folder, you can add individual/external JAR files, you can link projects, etcetera. Make use of it. Forget about using the CLASSPATH environment variable. It was a mistake by Sun Oracle. They thought to convince starters, but it ended up to be only more confusing to starters as they incorrectly interpret that environment variable as the classpath.
See also:
How to add JAR libraries to WAR project without facing java.lang.ClassNotFoundException? Classpath vs Build Path vs /WEB-INF/lib
What finally helped me out was to copy the mysql-connector-java-5.1.15-bin.jar to \jre\lib and to \jre\lib\ext both(!) even though I did all the classpathing circus Java offers :) Environment was pure notepad/commandline though.
What worked with me using Netbeans was:
Run > Set Project Configuration > Customize.
Under Libraries > Add Library. Added MySQL JDBC Driver (I assume it appeared in list because I copied the jar file to the jre\lib\ext folder.
And it worked seamlessly.
I tried setting classpath but that did not work. I am using Netbeans 7.0
simply do a right click on your project in "Netbeans" select properties then click on "libraries " then click on "add library..." button then select "MySQL JDBC Driver" and click on "add library" button then on "OK" button
I also had this problem before, but after I put/added mysql-connector-java-5.1.34-bin.jar (Download it from here) into the apache-tomcat-8.0.15\lib folder, and then ran my project, it really did work.
Note : Even after adding the jar file the error persists, then restart the Tomcat server and rerun you project again.
Open Netbeans IDE
Right-click your Project.
Select Properties.
On the left-hand side click Libraries.
Under "Compile" tab - click Add Jar/Folder button.
Select Downloaded "mysql-connector-java-5.1.25-bin.jar" file (Download Connector/J from dev.mysql.com)
Click OK
Run Again... Its work.
If you are using maven, add the dependency to pom.xml should solve the problem.
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.36</version>
</dependency>
In Netbeans IDE just Check the properties of Project on which you working on,in properties window go to 'library' tag, in diolog box just add your mysql-connector-java-**.jar file.
I had this same problem in Netbeans. Because I was using a tomcat connection pool as defined in context.xml I needed to add the jdbc jar to both the project (Properties->Libraries) and to the lib/ folder within my Tomcat server so it could be seen on startup.
I have a java based web application, which has certain java files and due to some need, i have added some jar files with in the project and made it project specific.
Now, While deploying them in production, I see, that the web file server (tomcat6) already has those jar files in its global library. Now, How do i remove reference of that jar file it, with out disturbing my code(which is working fine).
I saw in other article saying we just have to change the build path to refer the global library instead of local library.
Finally I have 2 questions.
How to do this?
If i'm working on windows and using path while configuring the build path, will it not be a problem if i deploy it in Unix environment.?
Please suggest. Also, its the problem with servlet-api.jar.
I use eclipse IDE. So how to perform these changes in eclipse?
Open your web project in eclipse and right click on the project. click on Properties and then choose build path and remove the jars you want to remove under the tab 'Libraries' and then export the war and deploy it in your tomcat6 server. if you want to run your web application in eclipse, you have to configure the server libraries by clicking 'Add Library' button in build path and then choose server runtime and choose the tomcat6 server configured in eclipse. Hope this helps
I am trying to connect to mysql database using java on windows7. In spite of adding the complete url of jdbcdriver jar file in CLASSPATH, java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
is thrown. Could anyone tell me what i am missing here? It works if I add the jar file in project library but I want to do it by CLASSPATH itself.
My classpath looks like this-
C:\jython2.5.1\javalib\mysql-connector-java-5.1.12-bin.jar
I want to make it clear that this is not the actual project i am working on. I am actually using Django with Jython, which requires the JDBC driver to access the database. That is the reason why I have to do it using CLASSPATH only.
The CLASSPATH environment variable is only used by the java.exe command and even then only when used without any of the -cp, -classpath, -jar arguments. It is ignored by IDEs like Eclipse, Netbeans and IDEA.
That environment variable is in real world also considered a poor practice since it breaks portability. I.e. program X will run successfully while program Y won't run without altering the CLASSPATH. It's only "useful" for Sun Oracle to prevent that starters get tired of typing the same classpath again and again in the -cp or -classpath arguments when following Java tutorials. In real world, batch/shell files are preferred where just the entire command with -cp/-classpath argument is specified.
In your case you're using an IDE. The classpath is there called the "Build Path". In plain Java projects, it represents both the compiletime and runtime classpath. You can configure it in the project's properties. You can add a complete folder, you can add individual/external JAR files, you can link projects, etcetera. Make use of it. Forget about using the CLASSPATH environment variable. It was a mistake by Sun Oracle. They thought to convince starters, but it ended up to be only more confusing to starters as they incorrectly interpret that environment variable as the classpath.
See also:
How to add JAR libraries to WAR project without facing java.lang.ClassNotFoundException? Classpath vs Build Path vs /WEB-INF/lib
What finally helped me out was to copy the mysql-connector-java-5.1.15-bin.jar to \jre\lib and to \jre\lib\ext both(!) even though I did all the classpathing circus Java offers :) Environment was pure notepad/commandline though.
What worked with me using Netbeans was:
Run > Set Project Configuration > Customize.
Under Libraries > Add Library. Added MySQL JDBC Driver (I assume it appeared in list because I copied the jar file to the jre\lib\ext folder.
And it worked seamlessly.
I tried setting classpath but that did not work. I am using Netbeans 7.0
simply do a right click on your project in "Netbeans" select properties then click on "libraries " then click on "add library..." button then select "MySQL JDBC Driver" and click on "add library" button then on "OK" button
I also had this problem before, but after I put/added mysql-connector-java-5.1.34-bin.jar (Download it from here) into the apache-tomcat-8.0.15\lib folder, and then ran my project, it really did work.
Note : Even after adding the jar file the error persists, then restart the Tomcat server and rerun you project again.
Open Netbeans IDE
Right-click your Project.
Select Properties.
On the left-hand side click Libraries.
Under "Compile" tab - click Add Jar/Folder button.
Select Downloaded "mysql-connector-java-5.1.25-bin.jar" file (Download Connector/J from dev.mysql.com)
Click OK
Run Again... Its work.
If you are using maven, add the dependency to pom.xml should solve the problem.
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.36</version>
</dependency>
In Netbeans IDE just Check the properties of Project on which you working on,in properties window go to 'library' tag, in diolog box just add your mysql-connector-java-**.jar file.
I had this same problem in Netbeans. Because I was using a tomcat connection pool as defined in context.xml I needed to add the jdbc jar to both the project (Properties->Libraries) and to the lib/ folder within my Tomcat server so it could be seen on startup.
I recently switched to J2EE from .NET, and am confused about where to put JAR files. I know that the CLASSPATH, WEB-INF, and Eclipse's Java Web Path are all places where JARs can be stored, but I'm confused about which folder to use, when, and why.
First off, we have the CLASSPATH. I usually set this by going into "Environment Variables" inside "My Computer." I know that this is the default place where the Java compiler looks for JAR files. When I add a folder or a JAR to my CLASSPATH environment variable, why is it ignored by Eclipse, the Java compiler, and the web server?
Also, I know that WEB-INF\LIB is a place where you can put JAR files that your web app is going to use. However, I've put JARs in WEB-INF\LIB only to have them be ignored. In what situations should I put JARs into WEB-INF\LIB folder? How do I get Eclipse or the web server to notice them?
So far, the only thing that works for me is to actually change the Java Build Path for an Eclipse project. I'll select the JARs I need and hit "Add External JARs." Most of the time when I do this, Eclipse will recognize my JARs and read the classes therein. However, I've run into a bunch of weird random errors while doing this (mostly having to do with dependencies, I think). For some reason, I just get the feeling that this isn't the right way to do things, and that I'm missing some vital piece of information. When should I be manually Adding External JARs inside Eclipse, and when should I be doing things differently? How come Eclipse's Java Build Path doesn't seem to know about the folders in my CLASSPATH environment variable?
Really, I would just like to gain a better understanding of the CLASSPATH, Eclipse's Java Build Path, and the WEB-INF/LIB folder -- the purposes they serve, the relationships between them, and where I should be putting my JARs in various situations. I would appreciate any advice you could give me, or any articles that you could recommend.
Thank you.
The CLASSPATH you set in your environment affects only standalone Java applications, i.e. ones you run from a command prompt or an icon. As you've noticed, Eclipse ignores this. It sets up its own per-project classpaths.
javac and java, if called from the command prompt, should/may honor this path, but it's no longer considered great practice to do this. It's turned out that every app needs its own set of stuff, so a global CLASSPATH isn't really doing any of them any good. Modern practice is to simply specify the classpath with the -cp option on the command line for javac or java.
A standalone Web Application server will also set up its own classpath. From the command line or GUI, WebAppServers are usually started by a script (.BAT or .sh) that sets up a classpath using -cp. Tomcat has a directory called common or common/lib where it expects to see libraries that should be available the the server and all programs running under it. But you will generally not need/want to mess with this, as it's customaries for applications to provide their own library collectons in WEB-INF/lib.
So for a Web app, you'd put your varous jars into the lib directory, under WEB-INF, assuming Eclipse pre-builds such a directory structure for you.
All the libs you need also need to be made known to Eclipse. In the Project Explorer, I select the whole slew of them at once, right-click and select Build Path | add to build path. That's easier than messing with Eclipse's project build path manually.
Java has a long history and experience has shown that some ideas were good and some were bad.
The CLASSPATH environment variable was the initial way to tell the Java machine where to locate classes from your program, and works reasonably well for command line programs. It was rapidly found that this should not be a global thing (as that tend to mess things up in the long run) but a per-program thing. This could be done by creating a wrapper script/BAT-file which sets the variable and runs the Java machine.
All was well, then people wanted to write web server stuff in Java. The Servlet API was created where a web application is a stand-alone unit - this resulted in that the CLASSPATH for each web application is the unpacked files under WEB-INF/classes plus the jar-files under WEB-INF/lib. And only that. This means the global CLASSPATH variable is ignored. This has been found to be a VERY good thing, so the concept has migrated elsewhere.
For instance a "executable jar" (which Eclipse calls a "runnable jar") which is invoked with "java -jar foobar.jar" contains the complete classpath INSIDE the Jar in a special manifest file. Java Web Start which is used to start java programs from a web server explicily lists the full classpath in the configuration file on the server.
But, to get you started. If you want to write a Java web application:
Get the Eclipse Java EE version.
Create a new Dynamic Web Project e.g. named foobar.
Drag and drop (or copy/paste) the jar files you need in foobar/WebContent/WEB-INF/lib
Create a new file named foobar/WebContent/index.jsp. In the blank file type <h1>Hello World <%= new java.util.Date() %></h1>
Right click in editor for index.jsp, choose Run -> Run on Server, and choose the Basic -> J2EE preview at localhost server, and Finish.
A browser window will now open, either in a browser or inside Eclipse which will render your JSP-page. You can change the JSP-page, save it with Ctrl-S and reload the browser window to see the changes.
Also, I know that WEB-INF\LIB is a place where you can put JAR files that your web app is going to use. However, I've put JARs in WEB-INF\LIB only to have them be ignored. In what situations should I put JARs into WEB-INF\LIB folder? How do I get Eclipse or the web server to notice them?
The real problem you have here is likely that you didn't got Eclipse for Java EE developers and/or that you just created a generic Java Project instead of a Dynamic Web Project and built up the necessary folder structure yourself.
If you create a Dynamic Web Project in Eclipse for Java EE developers, then Eclipse will automagically add any libraries in WEB-INF/lib to the build path. The build path is roughly said just the classpath which is been used in both compiletime and runtime. With other words: just drop the 3rd party JAR's in there, really nothing more needs to be done.
Note that Java is case sensitive, thus it should be really called WEB-INF/lib, not WEB-INF/LIB. But anyway, if you create a Dynamic Web Project, then Eclipse will just automagically generate the correct folder/file structure for you.
As said by others, ignore the %CLASSPATH% environment variable. It is only used by javac.exe/java.exe and even then only when you do not specify any of the -cp, -classpath or -jar arguments. In real world this environment variable is seldom used, it is just some convenience for starters (and unfortunately also the most confusing one, they should never have invented it).
If you're dealing with web applications, /WEB-INF/lib is the portable place to put JARs. This is where web servers servlet containers expect to find an application's jar files.
Eclipse requires you to specify the path to your libraries, jar files (on Properties -> Java Build Path -> Libraries tab). This can be found on the .classpath project file.
Usually you have the JRE libs on its path (which would be on your classpath too), so adding the libs to the classpath and updating eclipse build path would work.
The WEB-INF directory should be the place that contains necessary information for your web application.
I'm not an Eclipse expert, but I think that your problem can be answered like this:
1) CLASSPATH is an environment variable that is read in when you launch java programs and is used by classloader to figure out where the classes are placed.
I would modify the CLASSPATH variable only in the case when you are launching an java program from a script, as this allows you to conveniently launch a program and make sure that the classes are found. This would not be the case for you, as you are developing the web application.
2) WEB-INF/lib is the directory under which the web application container's classloader (like tomcat or glassfish) looks into if your web application needs to resolve a class. So you put there the classes that are used in your web application.
Some IDE's do include the libraries/.jar files that you are using in a project automatically to the package.
3) Eclipse library/classpath resolving during the development time. I would assume, but apologies for assuming, as one really shouldn't do this ;), that you can define a library (add external .jar files to projects) and autocomplete/all the other interesting features should start working with this, as you basically make those classes visible for the IDE with that activity. I also would assume that you can then mark those libraries to be automatically added to the web projects etc., by the IDE.
In general a good reading about how classes are found during execution is here (it's a sun's official documentation). Also a good place to read about this is the ClassLoader class documentation.
Taken together the comments helped me as well. I had added all the jena .jars to the build path from eclipse but that wasn't sufficient. Following suggestion to "add to WEB-INF/lib" it seemed intuitive to drag from libraries folder to WEB-INF (from within eclipse), but that didn't work. Nor did copying the .jars to WEB-INF. I eventually drag-and-dropped from the windows desktop to the WEB-INF lib folder in Eclipse, and that fixed the problem. It would be nice if any .jars added to the build path were automatically copied to WEB-INF lib by Eclipse. In case it matters, this was eclipse EE IDE, Indigo release, on windows 7.