Combining a maven project with a java project - java

Currently, I have a maven project that has a server running (using Jersey REST API). I also have a java project, I need to move all the contents of the java project into the maven project. The maven project is a subset of the java project. However, the maven project only displays the parts of the java project. However, I want a project that allows me to use maven and displays all of the other details from the java project.
I would've copied and pasted however I'm using git so I want to also preserve history.
I was thinking it would be easier to nest the maven project inside the java project but I don't know if that's possible.
Here's a picture of my package explorer to help explain everything.
Package explorer showing the maven project being a subset of the java project.
What I've tried is converting the java project into a maven project and then updating the pom.xml but then it doesn't link to the web.xml. Also, it tries to run the server with the name of the project name TeamProject. When infact it should run the url with the name client_server
I was considering just copying and pasting all the code into the maven project (from the Teamproject java project).

Actually nesting the java project inside the Maven project makes more sense, as it is the purpose of Maven to handle a project lifecycle. (also by default Maven will look for sources in the src/ folder which should ease the task of putting your Java project inside Maven's hands)
There are several possibilities I would see:
Copy your java project in the src/ of your client project and update maven accordingly (within the pom.xml)
Make your Java project a Maven project and aggregate the two projects in a parent pom (see Multi module maven project example)
Make your Java project a Maven project, and decide of a "Master" project between it and the client and compose one with the other (not sure that's a great solution)
Nesting your Maven project inside the Java project would not be so great because Maven could only handle the client and not your Java project, and then you'd miss on numerous functionalities offered by Maven (just look at how simple it is to get dependencies compared to downloading a jar and including it on the build path manually)

Related

How to reference classes from a Maven project in Eclipse 2019-09?

Using Eclipse 2019-09, my goal is to use OpenPDF library, but first, I need to be able to debug its code a bit when calling from my test project.
I have created a workspace where I have created a simple java program that would open a PDF.
I have cloned the OpenPDF repo, and I have added the projects to Eclipse. They are Maven projects.
Now, I need to setup the relation between the projects, in order to use OpenPDF code.
I've read here that I should add openpdf project to the Projects in Java Build Path of my test project, but that is not clear. If I add the openpdf project to the Classpath entry there, it's not compiling because it does not find the openpdf project classes.
So, what is the right setup? (I am not asking how to refer a library through Maven and I don't intend to build a signed Maven library).

Two Maven project with public module

I have a project that devided into three pieces, PCommon, PWebapp and PAdminConsole. PWebapp and PAdminConsole are dynamic web project in eclipse, PCommon is java project, and both two web project will use the api in PCommon as a jar file in lib folder.
In the past,I added import project in build path, I used Ant to compile and build PWebapp and PAdminConsole and in both build.xml file there is
<ant antfile="${common}/../build.xml" inheritAll="false"></ant>
to make PCommon into a jar file.
Now I will change all my projects to Maven Project. But I don't know how to make two web projects contain one public module, and how to package my PCommon into a jar file automaticlly when I run package maven command to package one web project.
Now I always deploy my PCommon.jar on nexus server. and then add dependcy in pom.xml in web projects. But I think there is no sense to deploy the jar on the public server, so I think it isn't the right way to archieve this goal. Is there any way that is more convenient?
I know I can make a parent project with a parent pom.xml. But I have two web project need the module, the pom.xml in PCommon can only extends one parent, can't it?
The common way to resolve dependencies in Maven is using a repository. The first time a dependency is needed, it is downloaded from your repository and installed in the repository on your local machine. If a dependency is not available in the remote repository it has to be installed to your local one in some other way. There are a few other ways to resolve depenencies without using the repositories but I wouldn't suggest to use the.
To make this a little more convenient, you can use a proper IDE. I use Eclipse with the m2e plugin. It supports something called "workspace resolution", which should be enabled by default. It scans your workspace for other Maven projects before falling back to the repository lookup. This has the advantage that every change you make in your common project is immediatly available in the other projects. I think it also gets installed to your local repository in the background but I'm not sure. Anyway you don't have to worry about it yourself.
Something similar works with IntelliJ IDEA but I don't have that much experience with it. I'm sure Netbeans has some kind of Maven support too.

How to add Maven to existing Java WebApplication in IntelliJ?

There is standard Java WebApp project. I need to use Maven to build/compile/deploy project to online server. There is an option to create new maven module module or to import project using pom.xml. Following probaby won't work because:
Project doesn't have maven project and pom.xml
Creating new maven module probably would mess up my existing project structure.
How to add Maven support to existing Java WebApplication in IntelliJ 12?
UPDATE:
I selected Add framework Support... > Maven. Generated pom.xml at project's root. Added maven-war-plugin. The following structure I have got. Is it any good / correct?
You should use maven standard project structure for maven applications. However, if you cannot change it, then you have to tell Maven where to look for specific files. Consider:
Using maven using non standard directory layout
Standard Maven structure
Also here are some interesting things to remember: http://wiki.jetbrains.net/intellij/Maven_FAQ

How and where does a pom.xml will be configured to be invoked by a web project

I have been working on maven for some time but never had this question before, Many times I created my maven project using a IDE wizard which helps me to create a maven project which has pom.xml pre-configured or the other way is to convert a general java project into maven project which generates a pom.xml. I have a question what exactly happens in the background when we convert this java project into a maven project. What will be configured and how does the java project detects it has a pom.xml.
Inside the .project file in the root of the Eclipse project, m2eclipse will add the org.eclipse.m2e.core.maven2Nature to it. This tells Eclipse that the m2e plugin will handle various stages of the project lifecycle, and m2e has a hybrid partially-internal and partially-external engine that applies the instructions in the pom.xml to the project. (For example, it finds the classpath placeholders that are marked as maven.pomderived and replaces them with the appropriate Maven dependencies.)

Applying Maven to a project

I've been asked to apply Maven to a project. After browsing a dozen sites it appears that it's quite vast and I'm not familiar as I'd like with similar tools like Ant. Why is it used/preferred and what does it offer over a standard Eclipse project? Also, how could it be added to an existing project?
Why is it used/preferred and what does
it offer over a standard Eclipse
project?
It is a build tool which can build your project without the need for an IDE like Eclipse. It can create a jar or war or other artifacts from the source, performing a bunch of steps like compilation, running unit tests, etc.
Where maven scores over ant is in managing third-party dependencies and in convention over configuration (which mean less lines of build script if you follow convention).
Also, how could it be added to an
existing project?
You start by creating a new maven project, following the step here.
Place it in the root folder of your project
If your source and resource files do not follow maven folder convention, update maven properties suitably referring to this documentation.
Run mvn package
It will fail if it needs any third party dependencies, which you can add as specified in the doc
With some trial and error, you should have your project running with maven, possibly, much quicker than if you were to set up the same with ant.
Others are already provided sufficient resources to read more about maven.
I suggest to start reading here:
http://www.sonatype.com/books/mvnref-book/reference/public-book.html
Maven is a great tool when you know how to use it. Maven (at core) is a dependency manager.
You include in your pom.xml (similar in function to the build.xml from Ant) all the librairies your project depends on (example : apache commons) along with their version and Maven get them directly from a repository (by default, the central maven repository)
Then you do not have to manually install any jar to make your project work. All is downloaded and cached on your local machine. You can even create an enterprise repository where you put all the jars needed by your company
Maven uses the concept of artifacts which are pre-built library projects with their own dependencies
To mavenize a project, you'll have to write a pom.xml describing your project (examples are numerous), get rid of your libs directory (or whatever classpath you described under Eclipse) and add all your dependencies to your pom.xml
You could also check Mavenizer for a first-start
But Maven is a lot more what i've just said. Read the docs, read poms from librairies and you'll get used to it quickly ;-)
If you use the M2Eclipse plugin from Sonatype, it's just a matter of right clicking the project in the package explorer and choosing Enable Dependency Management in the Maven menu. You are also advised to adjust the directories that contain the sources to the Maven standard directory layout but if you absolutely can't, you can configure that later.
Apart from that: Well, look for tutorials and documentation (for example there is the free book Better builds with Maven. Maven is very complex (yes, I don't think it is simple) and very powerful.

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