Maven use local jar without installing

You can install a local jar by using  mvn install:install-file command/goal as I discussed in my earlier blog post. This ensures the re-usability of jar file across your projects but as a drawback, this requires every team member and build server to run the same command/goal to build their project.

To avoid to the manual hassle, you can add the .jar in pom.xml file without running the mvn install:install-file goal. The idea is to refer a .jar from your project base directory using the <systemPath> element.

In example below, I put my jar files to /myjars directory and point to the jar file as

        <systemPath>${project.basedir}/myjars/[Jar file name]</systemPath>

Directory Structure

..
/src/..
pom.xml
/myjars/my-lib-core.jar
/myjars/third-party.jar

Pom.xml

<dependencies>
    <dependency>
        <groupId>com.my.library</groupId>
        <artifactId>mylib-core</artifactId>
        <version>1.VERSION</version>
        <scope>system</scope>
        <systemPath>${project.basedir}/myjars/my-lib-core.jar</systemPath>
    </dependency>

    <dependency>
        <groupId>com.third-party.library</groupId>
        <artifactId>thirdparty</artifactId>
        <version>1.VERSION</version>
        <scope>system</scope>
        <systemPath>${project.basedir}/myjars/third-party.jar</systemPath>
    </dependency>

For web project (war files )

If you are working on a web project, the above configuration won't add the jars to war file by default. You need to do following.

Here we are asking maven-war-plugin to add all jar ( **/*.jar) from  ${project.basedir}/myjars  to WEB-INF/lib folder when creating the war file.

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <configuration>
                <warSourceDirectory>src/main/webapp/</warSourceDirectory>
                <webResources>
                    <resource>
                        <directory>${project.basedir}/myjars</directory>
                        <targetPath>WEB-INF/lib</targetPath>
                        <includes>
                            <include>**/*.jar</include>
                        </includes>
                    </resource>
                </webResources>
            </configuration>
        </plugin>
    </plugins>
</build>

superclass "javax.servlet.http.HttpServlet" not found on Java Build Path - solution

You might (normally) get the error following error on a dynamic java web project created through maven on Eclipse IDE. The solution is simple :
Error :

The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path   

Error Location :

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

Solution 1)
Edit pom.xml to include servlet-api-x.x.jar in your dependencies:

<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.1.1</version>
  <scope>provided</scope>
</dependency>   

Solution 2)
Go to Project->Properties->Target Runtimes . And add your server container eg. : Apache Tomcat

change maven local repository path - symbolic links

Let's suppose we want to change the local maven repo path (default : c:\users\user_name\.m2\repository) to some other real folder - lets say e:\repo  - so that the contents from e:\repo folder are mapped to the default folder location.

This might be useful when .m2 folder on your C: drive is taking too much space. In such case, you can move the content to another drive ( e:\repo) and have a symbolic link on C:\ drive instead - so that all the configuration remains intact.

The following command creates a link folder "repository" in /.m2 folder and points to the source e:\REPO

C:\>mklink /d c:\users\gtiwari\.m2\repository e:\REPO


Note:

• Syntax : mklink /d TARGET SOURCE_DIR
• For more information about the mklink command visit : http://ganeshtiwaridotcomdotnp.blogspot.com/2014/08/using-symbolic-links-on-windows.html  
• we can do it using other options as mentioned in http://stackoverflow.com/questions/71030/can-i-add-maven-repositories-in-the-command-line

eclipse proguard maven project configuration - java obfuscate

I am going to describe how can can configure proguard and maven to obfuscate a java project. If you need help on how to configure maven project in eclipse see my earlier post.

A)Project configs

    <!-- Project configs -->
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.gt</groupId>
    <artifactId>maven-proguard-test</artifactId>
    <packaging>jar</packaging>
    <version>-ver.01</version>
    <name>maven-proguard-test-application</name>

    <properties>
        <project.build.mainClass>com.gt.App</project.build.mainClass>
    </properties>

maven install jar to repository locally

Run the following command to install the "MyJar-x.x.x.jar" into Local maven repository. The underlined  values vary in your case.

mvn install:install-file -Dfile=PathOFJar_MyJar-x.x.x.jar -DgroupId=com.mycompany -DartifactId=myJar -Dversion=x.x.x -Dpackaging=jar

After installing, Add the dependency into Pom.xml :

        <dependency>
            <groupId>com.mycompany</groupId>
            <artifactId>myJar</artifactId>
            <version>x.x.x</version>
        </dependency>

As an alternative, you can directly refer to a jar file in your file system. This eliminates the hassle that every team member and build server to run the mvn:install command every time someone adds some local jar in pom.xml.

Take a look at following blog post for the details.
http://ganeshtiwaridotcomdotnp.blogspot.com/2016/12/maven-use-local-jar-without-installing.html

Create, configure maven project in eclipse - example tutorial

In this post, the followings are covered :

• Download and Install maven in windows:
• Add M2_REPO classpath variable in eclipse 
• Generate Java/Web Project  with maven and import in eclipse
• Add another dependency from web repository
• Add custom or 3rd party library manually into repository:
• Benefits of using MAVEN :