I made a Hello word example in springMVC.Following are my steps.
1.Installed maven-eclipse integeration in eclipse.
2.Download maven and set environment variables,JAVA_HOME etc.
3.Check to see if maven is running via cmd and it is.
4.Create new maven project and in pom.xml,set spring core,web,web-mvc dependencies.
5.Create new Dynamic web project and under its properties->Deployment assembly I have added maven project.
6.Added spring jars core,mvc,web,context etc in dynamic web project lib folder.
It's all working now but I am not able to understand the working.
Before,I was trying to make it work without maven by copy and paste jars into lib,classpath,by makiing user library and adding jars to it and then add it to current project but every time it was giving some error.Sometimes it was classnotfound,sometimes it was context related.
Finally i tried this maven thing by searching some online tutorials and it works now.
But I am not able get it.Can anybody explain me in detail that how those spring jars getting picked during development and deployment.What exactly is maven doing that I was not doing before.I am in the state of total confusion.I know the flow of my mvc project(controllers,views etc.).
Maven searches the libraries (they are also called artifacts in the Maven language) in repositories. In the Maven Central Repository many libraries are hosted - http://search.maven.org/. After Maven finds the libraries in a repository, it caches them in your local repository. It is in ${userDir}/.m2 The next time, Maven will look in your local repository, instead of downloading again from the Central Repository.
P.S You can specify many other repositories different than the Central Repository. This is done in the <repositories> tag in your pom.xml. The Central Repository is always searched by default.
if you don't want use maven you have change your project setup. remove the pom.xml and copy all needed jar into the webapp/WEB-INF/libs folder.
Copy the jar from the a maven build(target folder). in this case you have all together without grabbing them one by one over then.
Related
I have started reading and trying maven since yesterday. But its making me go crazy.
I am java developer but never came across ant or maven before.
I want to know what exactly happens with the dependency tag in POM.xml file?
Lets say, I am using camel framework and want to use camel core jars.
If one of my class file contains following line:
CamelContext context = new DefaultCamelContext();
so what exactly I need to do after that?
Do I need to include the jars myself in the class path or dependency tag will download the jar files over internet for me?
If the case is former, what dependency tag will do? & where should I place my jar files? I mean is there any specific location on my hard drive? and
if the case is lateral then during compile time I get error "cannot be resolved to a type"
And the imports are to be specified or not?
I know the question might sound silly but I am not able to find its answer.
I have tried googling alot, it didn't help me still.
Any help would be greatful, even help on maven topics which I might come across in near future would be appreciated.
Thanks in advance.
Solved. Please check https://stackoverflow.com/a/20094312/1121208 for help
dependency tag will download the jar specified in the dependency tag for you if available. Otherwise will raise a pom.xml error - could not found dependency..
Imports have nothing to do with maven. They will appear when you will you another class in your class/java file. So if you import in build path the jar by yourserf or if you put it there with maven, you will have the import.
Are you using eclipse or any other ide ?
First of all, Maven is a build tool. It doesn't run your app. It builds it. So, at runtime, the classpath needs to be set like for any oter application yo would have built with something else.
When you build an app, you depend on external libraries. The dependencies mechanism of Maven simply lets you declare wwhich libraries your ap needs. When you build your app, Maven downloads these libraries from a central repository (or sevaral ones), and stores them in a local repository on your hard drive. These jars are automatically added to the build classpath by Maven. At runtime though, depending on the kind of ap you're building, you'll have to copy or embed those jars in order to create a runnable application.
The rules of Java don't change just you build them with Maven. Meven uses the stadard Java compiler (javac). And of course, if you want to use a class by its simple name, you'll have to add an import statement for this class.
I think that, before using Maven, you should try to compile and run a simple application depending on an external library without using any IDE. You would then understand better all the steps that are required to build and run an app, the concept of build and runtime classpath, etc.
Finally got what I needed to know
Sharing it for others who may stuck up in same situation
Does dependency tag download the jar specified?
maven dependency tag actually downloads the jar files you specify in the dependency tag. It downloads and save it under .m2/repositories(local repository) folder on your hard drive (along with some information like last updated, etc)
Local repository is shared among all your projects
from where it downloads?
It downloads the jar from the central repositories. There central repositories contain almost all the open source jar files one needs in a project. It downloads based on information you provide in groupid, artifactid, etc.
http://repo1.maven.org/maven/
http://mvnrepository.com/
can be checked for correct groupid, etc
Once these jar files are downloaded, they are automatically added to the classpath and are available in your project for use.
If the jar files you are searching for, are not available in the central repository, maven may throw error, in that case you can download it manually and let maven know about it.
Without maven you need to put jars into lib folder.
With maven you specify as declaration inside <dependencies>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
and when you do mvn package, maven will download required jars on your PC.
With Eclipse and m2e (maven eclipse integration) you can do that all not leaving Eclipse,
and even get sources for used libraries automatically.
Read http://maven.apache.org/ It worth it.
I am using m2e plugin.
Just stuck at one point when maven search for springMVC jar files where it would be searching.
In /web-inf/lib or in project build path.
Where should I put those jars
Thanks
Maven looks for jars in its repositories.
Therefore you don't need download jars manually when using Maven, it will automatically download jars from remote repository and put it to the local repository on your machine.
Maven uses "settings.xml" file to find out your project repositories. and resolve dependencies(every jar files that you need) from those repositories.
more about seetings.xml and also
this one .
After downloading required jar file for first time, maven puts it in your local repository in:
${user-home}/.m2/repository.
I have moved to Maven recently, and since it works fine for resources up to date in some repositories, it's not obvious for non-maven ones.
I have something very simple to achieve (in the idea), but that I am unable to express so far:
I need to compile my code with a jar that can be found here:
https://hudson.eclipse.org/hudson/view/WTP/job/cbi-wtp-wst.xsl.psychopath/ws/sourceediting/plugins/org.eclipse.wst.xml.xpath2.processor/target/
What do I have to put in my pom.xml to make Maven downloading the .jar + the java source + the javadoc, and eventually the other dependencies (actually IBM ICU, Xerces, JavaCup) that are mentionned in the supplied MANIFEST ?
I have read lots of documents, including those with a plugin called Tycho, but nothing helpfull for that simple task.
Thanks for your help.
Maven only works well if all artifacts needed for a build are contained in the local or a configured remote repository. So you have to do the following jobs:
Find out if eclipse plugins are deployed in a Maven2-style repository, and what the URL of that repository is.
Then find out which version of that plugin (artifact) you need.
Maven allows you to configure what will be copied locally: jar file, sources and api doc if you want to.
Maven should then be responsible to download as well all needed artifacts for the plugin you want to use.
After looking at the contents of the URL you gave us (especially the file p2content.xml), it looks like there should be a repository. I searched for the maven repository for org.eclipse.wst.xml.xpath2 and found the URL http://maven.eclipse.org/nexus/content/repositories/testing/org/eclipse/wst/org.eclipse.wst.xml.xpath2/1.1.0/org.eclipse.wst.xml.xpath2-1.1.0.pom
So the repository you are searching for is located at http://maven.eclipse.org/nexus. Just open it, search for example for xpath2, and Nexus, the repository software used there will you show the available artifacts. Depending on what was deployed to that repository, it may contain only the library, or have even sources and JavaDoc bundled with it. For the example above (xpath2), there seems to be only the POM itself and the library (the jar). If you take as example junit, you will find all versions and variants, even with sources.jar and javadoc.jar.
After you have found the needed artifact, you can include it in the dependency section of your POM. And you have to add http://maven.eclipse.org/nexus as a remote repository in the configuration of your Maven installation.
The question and its answer Get source JARs from Maven repository explain how to fetch sources and JavaDoc (if they are available).
You need a maven repository which contains this artifacts (i don't know, if Eclipse hosts a repository for their projects). You can also deploy manually the artifacts to a local repository on your computer.
I'm converting an ant backed Netbeans project into an Maven project. I've got most of the third party libraries set up in the POM, however now I've run into problems with setting up the local dependencies.
With the previous Netbeans way of doing things, it just added a project reference [with links to the source and jar location, rebuilt the dependency if the depedency's source had been changed and hadn't been compiled]. However I'm not sure how to setup up Maven to emulate this behavior. Is it possible?
Example:
Projects/SharedLibrariesResource [Ant based project]
Projects/WebSite [this is a maven based project]
Projects/Client
In this example the website and client projects don't connect to each other, but they do share the SharedLibrariesResource. Website should compile to produce a War with links to the SharedLibrariesResource
The way I understand the question, the Website maven project depends on the ant SharedLibrariesResource project. When Website is built, it should include the SharedLibrariesResource artifacts. The assumption is SharedLibrariesResources produces a jar artifact.
One way to achieve this is to
install SharedLibrariesResource to your local maven repository each time ant builds it
specify this as a dependency in Website pom.
We can use maven ant tasks to achieve the first.
I used Maven before in quite a few projects but they we already configured by someone else. I quickly understood the main concepts (groups, artifacts and versions for jars, local and remote repositories) so I assumed that if I'm asked I'll be able to set up a new project from scratch easily.
That turned out not to be the case when I deal with multiple modules which depend on one another. I poked around maven docs but they are either way too concise or way too technical (sometimes I get a feeling that Maven people wrote it for themselves and not for Maven users). So I'm asking for community help.
Here's a typical scenario:
Three repositories:
My local repo at <User>/.m2
My company repo at http://maven.mycompany.com/repository
Maven Central at http://repo1.maven.org/maven2/
I'm building a normal Java EE project consisting of one EJB jar with a corresponding client jar, a web module and a JPA module (I like keeping my entities and all db-connectivity separated from business logic). That gives me 5 project in my IDE:
myapp-ear
myapp-ejb
myapp-ejb-client
myapp-jpa
myapp-web
myapp-jpa is used by myapp-ejb and myapp-web. myapp-ejb-client contains business interfaces for my EJBs.
How should I set all that up? I suspect that I need some kind of parent project but I'm not sure how should I organize inter-project dependency resolution. For example: currently when I specify
<dependency>
<groupId>com.mycompany.myapp</groupId>
<artifactId>myapp-jpa</artifactId>
<version>0.1-SNAPSHOT</version>
</dependency>
in myapp-ejb's pom.xml maven tries to search for it in my repository and tells me that the .jar can't be found. Even if I build and install all app components into my local repository one by one Maven always fails to build the ear file itself :(
I'd love to get it working under Eclipse or NetBeans.
I think you're on the right path. You need a parent project to pull it all together. In the parent project (and here is the important part) you need your dependencies laid out NOT in the dependency section of your parent pom, rather, you need them in your dependencyManagement section. Then, in your child pom's you can declare dependencies that are in the parent.
The only other gotcha (that I can think of) is that when you check the project using a version control system in Eclipse you need to remember to check the parent project out "as Maven project" otherwise the m2Eclipse plugin tends to freak out and not resolve things properly.
I hope this helps.