I`m looking for the best way to convert a Java Project into a Maven Java Project.
I have a Java Project with libraries store locally and I would like to convert this project into a Maven project.
I could do that. In Eclipse a right-clicked into the project > Configure > Convert to Maven Project.
Following these steps, eclipse creates the pom.xml with artifactId, groupId, versions and etc.
I would like to know if there is any way to update the pom dependencies, for instance:
The project has a lib folder which contains all libraries/dependencies of the project, I want to update pom.xml (automatically) with these libraries so Maven can download it automatically.
Are there any way to do that automatically or you suggest to do it manually (verifying the static dependency and update the pom.xml with this dependency).
Thanks in advance.
Related
I have just started working with Maven in Eclipse.
I tried running a sample program in it, and I encountered some problems. The errors were in my pom.xml file. What is the significance of the pom.xml file in Maven?
In short the pom.xml will have all information to build your project.
For example you want to build a project and you have only the pom.xml sent to you via mail. If there are enough entries in the pom.xml then that is all you need! You can import it to Eclipse, Maven will download your source code from CVS, download various dependency jars (like Spring, Apache Commons), run your test cases, build the jar/war, deploy to your jboss/app server, generate a report of your code quality (using Sonar, maybe). Each task you want to do will be mentioned as a goal.
The links already provided are good enough for reference.
POM is an XML file that contains the project configuration details used by Maven. It provides all the configurations required for a project.
POM means Project Object Model, and, as the name suggests, it defines the model of the project as well.
In the normal project development you will add JAR files and libraries as required. In Maven-based development, those JAR files, libraries are added to the project using this pom.xml. In the pom context we call those JAR files, libraries as dependencies.
Maven is a build tool and pom.xml is the main file for the project.
The POM
The pom.xml file is the core of a project's configuration in Maven. It is a single configuration file that contains the majority of the information required to build a project in just the way you want. The POM is huge and can be daunting in its complexity, but it is not necessary to understand all of the intricacies just yet to use it effectively.
For more reference, check Maven in 5 Minutes.
POM stands for project object model. It's the fundamental unit of work in Maven. It is an XML file that contains information about the project and configuration details used to build the project. It downloads required libraries easily using POM XML tags.
When there is no Maven, it needs to add all the library JAR files one by one to the project. But when there is Pom.xml there is no need to add library JAR files one by one.
Simply add the dependency to the Pom.xml, and it will automatically add the library JAR files to the project.
pom.xml is a file which describes the project, configures plugins, and declares dependencies. The POM names the project, provides a set of unique identifiers (called coordinates) for a project, and defines the relationships between this project and others through dependencies, parents, and prerequisites.
A POM file can include a modules section, which tells Maven which directories have POM files which need to be built.
In the build section you can define plugins for which you need to build the artifacts in your project.
Pom.xml is part of your maven project, using pom.xml, maven life cycle you can achieve it.
The pom.xml is a project object model which tells everything 3rd party tool dependencies and library's and required plugins it will give everything to your project like project means any java based web content like itself. once you create the maven project you will get the pom.xml blog which is everything to handle your project
If you want to test your project, you need to add testing dependencies which is the maven community it will provide you once added it will have everything tested.
I've been coding Java in Eclipse for awhile without needing to specify dependencies. Now that I learned how Maven does it, I'm wondering: how did Eclipse build projects on its own? How did Eclipse figure out which versions of imports, and which dependencies of dependencies, are needed to make everything work?
Finally, what are the advantages and disadvantages of building a project in Eclipse by starting with New->Other->Maven Project instead of New->Java Project?
To the first question: Eclipse doesn't add any dependency in a standard Java project. You have to manually add to the Build Path all needed JARs, otherwise you'll have compilation errors.
To the second question: if you create a standard Java project Maven is not used, even if you create a pom.xml file in the root of the project. You can always convert a standard Java project in a Maven project (see Convert Existing Eclipse Project to Maven Project).
Your dependencies has always to be in the classpath
When you start a project with Maven, Eclipse will automatically add the Maven repository to the classpath.
When you start a Java project you have to link your library manually in Eclipse and the version of the library is the one you've downloaded.
You can see the difference in your project's Properties > Java Build Path > Libraries
I have a Netbeans Ant project that uses a Jar file generated from a Netbeans Maven project. I would like to "include" the Maven project directly in the Ant project to be able to proper debug both projects. The Maven project was converted from an Ant project and before the conversion this include was possible. I have control over both projects, but converting the Ant project to a Maven project is not really an option at this point. What is the best approach to make an Ant based project and a Maven based project "work" together i Netbeans?
Thanks
it should work if your ant project includes the maven local repository jar as dependency. Maven support does automatic binary->open project source conversion for local repo artifacts.
I created a new Maven project in Eclipse. This was working fine until I needed to add a dependency to another Eclipse project, a legacy utility project, which does not have a pom.xml, and does not have the directory structure of a typical Maven project. (It has the directory structure of a typical eclipse Java project). This other project is in the same Eclipse workspace as the Maven project.
In looking at other posts on this, it seems that usually the solution is to build the jar for the other project and install it in Maven. However I am actively modifying code in the utility project while writing code in the Maven project, so I can't just install a jar once to satisfy the dependency.
What is the easiest way to handle this so that I can code simultaneously in both projects, and also get maven to build cleanly? (Of course Eclipse can build just fine with just a project dependency.)
UPDATE
Using the Build Helper plugin to add the utility projects source folder to my pom was a viable path to the solution, but then I needed to update all the dependencies of the utility project into my new Mavne project, which started to make the whole process too time consuming (and also not really the chain of dependencies I wanted). I think that if I would have added all the dependencies, then Build Helper suggestion would have worked.
For now, I built the utility project jar and installed it into maven. Which turned out to be the the quickest solution. I will try to Mavenize the utility project, without modifying its structure (as suggested by FrVaBe below), and see if I can link the poms afterward.
I am going to keep this question open until I have a full solution which can be reported back, since I assume this is a problem others will have (trying to integrate legacy projects with new maven projects).
For the development time you can add the dependency as a System Dependency. It will be resolved by the file path (which can be the path to your utility.jar file under development) in this case.
It is added as describe in the link above, e.g.:
<dependencies>
<dependency>
<groupId>my-utility</groupId>
<artifactId>my-utility</artifactId>
<version>1.0</version>
<scope>system</scope>
<systemPath>${somewhere}/lib/my-utility.jar</systemPath>
</dependency>
</dependencies>
The maven handling of System dependencies is sometimes special. E.g. they will not be included in war-packages! Therefore, when you are finished I would strongly recommend to install your utility library to the maven respository or to deploy it to a repository manager (Nexus/Artifactory).
You can add utility project's src folder to your working project in eclipse. For your development purpose.
right click on Working project
go to properties and choose java build path
go to source tab
Add your utility project src folder to that.
Later you can install your jar as maven dependency.
For a project at work, we're considering using the Maven plugin for Eclipse to automate our builds. Right now the procedure is far more complicated than it ought to be, and we're hoping that Maven will simplify things to a one-click build.
My question is, is there a wizard or automatic importer for converting an existing Eclipse Java project to a Maven project, using the Maven plugin?
Or should I create a new Maven project and manually copy over all source files, libs, etc.
Start from m2e 0.13.0 (if not earlier than), you can convert a Java project to Maven project from the context menu. Here is how:
Right click the Java project to pop up the context menu
Select Configure > Convert to Maven Project
Here is the detailed steps with screen shots.
If you just want to create a default POM and enable m2eclipse features: so I'm assuming you do not currently have an alternative automated build setup you're trying to import, and I'm assuming you're talking about the m2eclipse plugin.
The m2eclipse plugin provides a right-click option on a project to add this default pom.xml:
Newer M2E versions
Right click on Project -> submenu Configure -> Convert to Maven Project
Older M2E versions
Right click on Project -> submenu Maven -> Enable Dependency Management.
That'll do the necessary to enable the plugin for that project.
To answer 'is there an automatic importer or wizard?': not that I know of. Using the option above will allow you to enable the m2eclipse plugin for your existing project avoiding the manual copying. You will still need to actually set up the dependencies and other stuff you need to build yourself.
I was having the same issue and wanted to Mavenise entire eclipse workspace containing around 60 Eclipse projects. Doing so manually required a lot of time and alternate options were not that viable. To solve the issue I finally created a project called eclipse-to-maven on github. As eclipse doesn't have all necessary information about the dependencies, it does the following:
Based on <classpathentry/> XML elements in .classpath file, it creates the dependencies on another project, identifies the library jar file and based on its name (for instance jakarta-oro-2.0.8.jar) identifies its version. Currently artifactId and groupId are same as I couldn't find something which could return me the Maven groupId of the dependency based on artifactId. Though this is not a perfect solution it provides a good ground to speed up Mavenisation.
It moves all source folders according to Maven convention (like src/main/java)
As Eclipse projects having names with spaces are difficult to deal on Linux/Unix environment, it renames them as well with names without spaces.
Resultant pom.xml files contain the dependencies and basic pom structure. You have to add required Maven plugins manually.
Right click on the Project name > Configure > Convert to Maven Project > click finish. Here you will add some dependencies to download and add your expected jar file.
This will create an auto-generated pom.xml file. Open that file in xml format in your eclipse editor. After build tag (</build>) add your dependencies which you can copy from maven website and add them there. Now you are good to go. These dependencies will automatically add your required jar files.
Chengdong's answer is correct, you should use Configure>Convert to Maven Project. However, I must add the conversion process has been greatly improved since m2e 0.13.0 : m2e 1.1+ and m2e-wtp 0.16.0+ can now convert the existing eclipse settings into maven plugin configuration .
As for the dependency conversion matter, you can try the JBoss Tools (JBT) 4.0 Maven integration feature, which contains an experimental conversion wizard, plugged into m2e's conversion process : http://docs.jboss.org/tools/whatsnew/maven/maven-news-4.0.0.Beta1.html.
It does not pretend to be the ultimate solution (nothing can), be it should greatly help bootstrap your Maven conversion process.
Also, FYI, here are some ideas to enhance m2e's conversion process, refactoring to use a Maven layout will most probably be implemented in the future.
JBT 4.0 (requires Eclipse JavaEE Juno) can be installed from http://download.jboss.org/jbosstools/updates/stable/juno/ or from the Eclipse Marketplace
It's necessary because, more or less, when we import a project from git, it's not a maven project, so the maven dependencies are not in the build path.
Here's what I have done to turn a general project to a maven project.
general project-->java project
right click the project, properties->project facets, click "java".
This step will turn a general project into java project.
java project --> maven project
right click project, configure-->convert to maven project
At this moment, maven dependencies lib are still not in the build path.
project properties, build path， add library, add maven dependencies lib
And wait a few seconds, when the dependencies are loaded, the project is ready!
There is a command line program to convert any Java project into a SBT/Maven project.
It resolves all jars and tries to figure out the correct version based on SHA checksum, classpath or filename. Then it tries to compile the sources until it finds a working configuration. Custom tasks to execute per dependency configuration can be given too.
UniversalResolver 1.0
Usage: UniversalResolver [options]
-s <srcpath1>,<srcpath2>... | --srcPaths <srcpath1>,<srcpath2>...
required src paths to include
-j <jar1>,<jar2>... | --jars <jar1>,<jar2>...
required jars/jar paths to include
-t /path/To/Dir | --testDirectory /path/To/Dir
required directory where test configurations will be stored
-a <task1>,<task2>... | --sbt-tasks <task1>,<task2>...
SBT Tasks to be executed. i.e. compile
-d /path/To/dependencyFile.json | --dependencyFile /path/To/dependencyFile.json
optional file where the dependency buffer will be stored
-l | --search
load and search dependencies from remote repositories
-g | --generateConfigurations
generate dependency configurations
-c <value> | --findByNameCount <value>
number of dependencies to resolve by class name per jar
https://bitbucket.org/mnyx/universalresolver
My question is, is there a wizard or automatic importer for converting an existing Eclipse Java project to a Maven project, using the Maven plugin?
As far as I know, there is nothing that will automagically convert an Eclipse project into a Maven project (i.e. modify the layout, create a POM, "generate" and feed it with metadata, detect libraries and their versions to add them to the POM, etc). Eclipse just doesn't have enough metadata to make this possible (this is precisely the point of the POM) and/or to produce a decent result.
Or should I create a new Maven project and manually copy over all source files, libs, etc
That would be the best option in my opinion. Create a Maven project, copy/move sources, resources, tests, test resources into their respective directories, declare dependencies, etc.
For converting to Gradle is analogue to Maven:
Right click on Project -> submenu Configure -> Convert to Gradle (STS) Project