I have an existing eclipse project with standard dependencies in the classpath. I need to add a new dependency through maven but the rest of the dependencies need to stay there as jars bundled with the project.
I am using m2e, if I right click on the project --> maven --> enable maven, a pom file is created. At this stage I can add my new dependency through the pom file but all the existing dependencies seem to be gone from the classpath.
Hence the question: Is there a way to create a hybrid project that has both standard dependencies and maven dependencies?
You could add your legacy dependencies by using the scope "system" (and the tag "systemPath") ?
See http://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html.
I don't think you should even attempt to create such a thing, and I don't know why you would want to.
If you want to use Maven, then you should define all your dependencies in your pom so that a maven build will actually work. If all your dependencies aren't defined, how do you expect maven to build your project?
You need to decide which means of dependency resolution you want to use instead of trying to mix two together.
Related
I have added a Java project dependency in Maven dependencies however if I add the same dependency in build path it works. What is the difference between these 2 methods?
Adding your project as maven dependency would mean that
You don't have to bundle your jar with your project.
You don't check in your .classpath and .project eclipse meta files in your source control
Any other programmer in your organization will be able to build your application.
You should not manually add jar file in eclipse build path. Its an anti pattern.
Both works because eventually your application need classpath which is set both by adding dependency manually as well as adding in build path.
I'm working one an Eclipse RCP project. Currently we create a dependencies plug-in project and put all jars libraries into that project and export all packages. This method will give a huge repo, thus we want to use Tycho/Maven and let it figure out the dependencies for us.
The first approach is removing dependenciec project and use p2-maven-pluging to transform existing jars libraries to p2 format repo. Install all libraries from p2 repos and add required bundle in Require-Bundle section in each MANIFEST.MF. This is a little bit tedious since in every project having dependencies in Require-Bundle, I have to manually replace it to corresponding bundle names. And in the end, the project build using Tycho could successfully run, but in Eclipse it gives me java.lan.NoClassDefFoundError: Could not initialize class X.
I think there are few configuration files, where Tycho depends on some of them and Eclipse depends on the rest, but I'm not sure what it is.
The second approach is removing all jars in dependencies project but adding them in Require-Bundle or Import-Package. However, both won't work since in Export-Package section Eclipse will complain these packages are not existed. Thus other projects depends on this dependencies project won't find those packages they need, which causing more errors in Eclipse.
Does anyone know the best practice to deal with this issue?
Update:
I'm using basically the first approach, but add dependencies in Import-Package in each project instead of Require-Bundle. This would eliminate the need to specify the specific bundle version, as long as they provide the same API and they are compatible, your application would work. So everytimes I update private p2 repository, I don't need to change MANIFEST.MF in each project.
The only MANIFEST.MF I need to manually add dependencies in Require-Bundle is a library developed by our self. Without it, Tycho won't fetch required dependencies from private p2 repository. If still get NoClassDefFoundError, try adding all plugins in Run -> Run Configuration .. -> plug-ins, it may help.
I definitely not apply your approach 1, with the mega-plugin of exports. There's a related discussion here: Handling non-OSGi dependencies when integrating Maven, Tycho and Eclipse
As a rule, use Import-Package instead of Require-Bundle.
To get bundles will appear in the Export-Package section Eclipse:
if they are non-Eclipse (maven libraries), then build the project and reference the libraries in the Eclipse runtime section.
if they are Eclipse dependences, they should be in your workspace or Target Platform.
More generally, it may help for you to define a Target Platform. You can build/deploy all of your locally created plugins into a local p2 repository (see http://www.sonatype.org/nexus/). Then add that p2 site to your Target Platform.
I thought I understood Maven as I've worked on a few projects using it, but I seem to be having trouble creating my own project with it, so can someone correct me wherever I may be wrong?
Assuming I create a new Maven project (we'll say I did it through Eclipse or IntelliJ):
If I add a dependency to my POM file, assuming I add a public repository where that dependency can be found, shouldn't the IDE download the specified JAR and make it so that it is recognized when I use it in my code? Currently, my projects do not recognize any classes that should be found in JARs via my POM dependencies.
Assuming #1 does work, how can I determine via maven which transient dependencies I have? For example, I'm using classes from Pentaho Data Integration, and some of the plugins for it reference things like org.mozilla.javascript.*. Could maven automatically tell me that without me having to run the code, see it fail, and manually fix the dependency? There will be hundreds of those instances here, so manual fixing really isn't viable.
Here are my IntelliJ two cents:
1 - Adding a dependency in pom.xml of your project
Should indeed download the depended jar(s). You may need to approve "Import Changes" dialog if it pops in, or enable auto import.
2 - Seeing transitive dependencies
It can be achieved via Maven Dependencies Diagram - unfortunately only in IntelliJ Ultimate edition. You can use Maven Dependencies Plugin to see the dependencies tree in your favorite CLI.
Question 1: Adding a dependency
In Eclipse, depending on how you created the project, you should be able to add dependencies that are automatically recognized using the maven context menu.
Note that you should have created the project using the eclipse maven plugin so that it has maven nature.
To add dependencies/plugins from a remote repository, you can search in the resulting UI for a dependency if you know the artifactId or groupId. The plugin will pull up the deps whether the repo url is specified in the pom.xml or not.
After adding a dependency to the POM, the IDE will start downloading it and all transient dependencies as soon as you save the file.
If something goes wrong, you can try to "Update Project" from the context menu.
Question 2: Determining transitive dependencies
Transient dependencies are visible in the "Dependency Hierarchy" tab of the POM editor.
I usually default to the command line because it allows much more flexibility and functionality when tracking the dependency graph.
I am sorry but I have not worked with IntelliJ
I have a dependency on clj-record in my CounterClockwise project. What's the best way to manage this? Copy the source code or compile to a JAR and add it as a referenced library?
There are tools to help you:
http://github.com/technomancy/leiningen <- project based
http://github.com/liebke/cljr <- dependencies not project based
http://github.com/ninjudd/cake <- alternative build tool
Assuming your dependencies are available in a Maven repo (like central or clojars), you have a couple of options.
First, if you're using Leiningen, there is an eclipse plugin for it now that will manage project dependencies for you, based on the dependencies you define in your project.clj file. The plugin is in beta now, but has been working great for me so far. (Note that it uses Leiningen 2.0 under the covers, though that detail won't matter for many (most?) simple cases.)
If you're using Maven, the m2eclipse plugin makes it so that the dependencies you declare in your Maven pom.xml are automatically added to your eclipse project's build path, and are therefore available in CCW REPLs and such.
there seems to be no pattern for specifying dependencies apart from hacking the code into your project or building a jar externally.
Of course you can, just as with any java project. While dependency resolution isn't tied into eclipse (yet), once you retrieve the deps (via one of the command line tools nickik listed), you can specify which jars are to be included in the java build path of your eclipse project:
Retrieve the deps via cake, leiningen, etc.
Refresh the eclipse project so you see the deps (usually in the lib directory)
Highlight the jars you want eclipse to know about
Right-click, select Build Path > Add to Build Path
That's it. You can fiddle with the build path by going to the Java Build Path section of the project's properties window.
I am creating a new maven project from an eclipse plugin.
As it seems to me a bad idea to hardcode pom.xml to my plugin. Is there any way to generate this programmatically such that the plugin will be more maintainable ?
Also creating the maven project structure from the plugin on my own seems to be a bad idea too !
Is there any api to do this tast ? (creating a maven project, adding my dependency to it)
What I am currently doing is to create folders, write a .classpath file (hardcoded) , injecting maven nature to .project file and now trying to generate the pom.xml.
Seeing a pom.xml I thought writing one plugin for th ecurrent version of maven won't do a good job.
Not sure what you want/need to do exactly but you could maybe use the MavenXpp3Writer#write() method from the Maven Model API to write a POM from a given Model.
Sounds like you are trying to do the job of maven archetypes
mvn eclipse:eclipse