This it's probably going to be a question with a very easy answer... But I've been googling for a while and I didn't find any.
I'm working on a project that requires some classes to be used in more NetBeans projects (and EJB deployed on Glassfish and a client to call it).
Now, to make it work, I just imported the whole EJB project into the client project as a library, but everytime I launch the client, Netbeans redeploys the whole client and that takes a lot of time.
That's why I'd like to extract just those few interfaces I need from the server project, package them in a .jar and link that to the client.
In Eclipse it was easy enough (right click on your classes, export as jar). Here I can't really find anything of the sort. The only export option I see is used to export the whole project as a .zip.
(Copy pasting the .java files in the client project would also work but a .jar would be cleaner I think)
Not sure I understand the problem.
I use shared classes a lot, and package them into their own project.
Possible process:
Create new project, "Java class library".
Move the required classes to that project.
In your main project, open Properties, Libraries and "Add Project" to link to your library project.
I'me developping a java agent with Designer 8.5 with external jars in the project.
It works fine except when I close and reopen the project.
Then something quite strange happens: in the project build properties the references to jars are present but not taken in account, so there are compilation errors.
Then if I save a source file and come back to the project properties the references have gone.
So I must use the button "Add external jars" to redeclare them.
Has someone had this problem?
Mikkel Heisterberg has a great summary of the options available to you in regards to Managing external Java dependencies in Domino Designer
Basically, it boils down to:
Include the classes in the agent/web service you are writing
Put the classes in a Java script library and include the script library
Use the JavaUserClasses notes.ini setting
Put the classes in the jvm/lib/ext folder
Was that the information you were looking for? If not, please describe where/how you are using the external jars (Agents, Xpages, Managed Bean, ...).
I'm trying to import an API that I found online - joda time - into my program.
I've downloaded the files, stuck them in my source folder, but obviously since it isn't integrated into my program they won't work.
I've spent a lot of time googling around for different methods (maybe I'm searching for the wrong thing?) as well as just randomly doing a bunch of different things inside eclipse (I'm developing with eclipse) that include the word "package" or "import", to no avail.
I don't know if it's worth mentioning but my program is being built with the google app engine, and all their stuff is organized in a nice com.xxx.xxxx format, which I think is ultimately what I need to get my stuff into - I just don't know how.
Anyway, sorry if this is a ridiculously trivial question, and thanks in advance to anyone that helps.
You should just have to put the joda-time jar file inside the WEB-INF/lib folder of your project. This folder contains all the libraries that must be delivered with your application, and are automatically added to the build path of your project by Eclipse.
Since you are using Eclipse, you can use the library functions to add in external packages.
Right click on your project, and then choose Build Path --> Configure Build Path.
Click on the Libraries button at the top, and then click the Add External JARs... button.
Select the JAR file in your JODA directory.
If you are using the Eclipse deployment tools, this will automatically package your JAR file in to your web application. If it doesn't do that automatically, add that same JAR file in to your WEB-INF/lib directory (copy it in to your project).
I have a java application hosted on tomcat, which has a directory structure like :
webapps/my_aapp/WEB-INF/CLASSES/SERVLETS/xyz.java
webapps/my_aapp/WEB-INF/CLASSES/SERVLETS/xyz.class
so that's how classes are referenced .
Now (I am new to eclipse), it generates a different directory strucutre, in which all .java files are outside the code and I don't know where class files are stored.
The result is that when I upload the files, and compile, I get errors like this:
javac -Xlint servlets/Ajax.java
warning: [path] bad path element "/usr/java/jdbc7.2dev-1.2.jar": no
such file or directory
warning: [path] bad path element
"/usr/java/mysql-connector-java-3.0.16-ga-bin.jar": no such
What's the best way to understand this java directory path issue? Better yet, how to synchronize this structure?
I want to keep my eclipse directory structure on tomcat.
Typically eclipse stores all class files under bin directory located under your project near src directory.
I personally like name classes more than bin, so I always change it when I am creating project or later using project properties (right click on project -> properties -> build class path.)
Check your disk, I believe your class files are there. Unless you are using some pluging that can change this behavior.
What kind of project are you using in eclipse? A WEB project? An ANT-build project? MAVEN build? The way it builds classes depends on it. There is not much that I can help you. Because you do not provide enough detailed information with your question, but I will try.
Anyway, you can configure your output dir to be web/WEB-INF/classes (which is not statndard and not recommended, but I am doing it in one old project ;D) if you have it configured as java project.
1. Right click on project,
2. Go to Java Build Path
3. go to source tab, select source folders and select output folder (in my project mypoject/web/WEB-INF/classes ).
4. If you want to run and debug on apache tomcat from withint eclipse using this configuration, you can use eclipse sysdeo tomcat plugin.
Other thing is: You have specified absolute links to libraries (I suppose looking at your error messages), please copy them to web/WEB-INF/lib and change links in project settings. (If you are using maven that you should learn maven, if you are using ant, than just rewrite the part thaht uses these libs). And check if you already has this libs in tomcat/shared or tomcat/lib classes.
Another way is to learn to work with standard way of creating web-projects in eclipse, and add a build and package tasks to your build process (whatever it is make, ant or maven). Then you should deploy your PACKAGED application (let it be *.jar).
My suggestion, please, read "Head First Servlets & JSP by Kathy Sierra, Bert Bates, Bryan Basham" this is great book. It has everything you should know about HTTP, JSP, servlets, tomcat, and web-application directory structure. It will make things much easier for you (at least it worked for me, it really helped me much to understand things, and it is great fun to read).
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.