Maven POM file - Yash-777/LearnJava GitHub Wiki

Available lifecycle phases|goals are:

validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy

To run any other goals like shade:shade of shade plugin along with package goal, we run as mvn package shade:shade. By using executions we can add shade goal to run along with package goal as shown below. mvn package.

Creating a Shaded JAR « The goals for the Shade Plugin are bound to the package phase in the build lifecycle.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>

        </execution>
    </executions>
</plugin>

How to create a jar containing test classes 

<executions>
  <execution>
    <goals> <!-- ScreenRecorder-0.0.1-SNAPSHOT.jar, ScreenRecorder-0.0.1-SNAPSHOT-tests.jar -->
      <goal>test-jar</goal>
    </goals>
  </execution>
</executions>

Specifying resource directories

if we have a resource on some location « src/main/resources/config.properties | target/my-resources/localDev.jar and if we want to place them in class path « target/classes/config.properties | target/classes/localDev.jar So, that they will be packaged in to jar/war/zip file.

<build>

    <resources>
      <resource>
        <targetPath>./libClasspath</targetPath>
        <filtering>false</filtering>
        <directory>${project.build.directory}/my-resources</directory>
        <includes>
          <include>**/*.txt</include>
        </includes>
        <excludes>
          <exclude>**/*test*.*</exclude>
        </excludes>
      </resource>   
    </resources>   
</build>

Download maven dependencies and save into specified folder my-resources. Executable jar with dependencies

we specify the goal copy-dependencies, which tells Maven to copy these dependencies into the specified outputDirectory.

<build>

    <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-dependency-plugin</artifactId>
        <executions>
            <execution>
                <id>copy-dependencies</id>
                <phase>prepare-package</phase>
                <goals>
                    <goal>copy-dependencies</goal>
                </goals>
                <configuration>
                    <outputDirectory>${project.build.directory}/my-resources</outputDirectory>
                    <overWriteReleases>false</overWriteReleases>
                    <overWriteSnapshots>false</overWriteSnapshots>
                    <overWriteIfNewer>true</overWriteIfNewer>
                </configuration>
            </execution>
        </executions>
    </plugin>

</build>

Executable JAR with Maven baeldung.com

  1. using maven-jar-plugin
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-jar-plugin</artifactId>
    <version>3.1.0</version>
    
    <configuration>
        <archive>
            <manifest>
                <mainClass>io.github.yash777.xuggler.VideoFrame</mainClass>
                <!-- 
                <arguments>  
                    <argument>arg0</argument>  
                    <argument>arg1</argument>  
                </arguments>
                 -->
                <addClasspath>true</addClasspath>
                <classpathPrefix>libClasspath</classpathPrefix>
            </manifest>
            
            <manifestEntries>
                <Class-Path>.</Class-Path>
            </manifestEntries>
        </archive>
        <descriptorRefs>
            <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
        
        <!-- <finalName>webappJar</finalName> -->
        <charset>utf-8</charset>
    </configuration>
</plugin>

META-INF « MANIFEST.MF classpath

Manifest-Version: 1.0
Built-By: yashwanth.m
Created-By: Apache Maven 3.3.9
Build-Jdk: 1.8.0_144
Main-Class: io.github.yash777.xuggler.VideoFrame

Class-Path: libClasspath/xuggle-xuggler-5.4.jar libClasspath/slf4j-api-1.7.2.jar libClasspath/slf4j-simple-1.7.2.jar
  1. using shade plugin & Selecting Contents dependent jar file .class file for Uber JAR includes-excludes

Use the maven-shade-plugin to pull in dependencies to make the standalone.jar. shade:shade

Artifacts are denoted by a composite identifier of the form groupId:artifactId[[:type]:classifier].

In order to generate shaded jar like ScreenRecorder-0.0.1-SNAPSHOT-shaded.jar we use: <shadedArtifactAttached>true</shadedArtifactAttached> «

To create source code jar for the available lsit of shade artifacts like ScreenRecorder-0.0.1-SNAPSHOT-sources.jar we use <createSourcesJar>true</createSourcesJar>.

The plugin can also be configured to automatically remove all classes of dependencies that are not used by the project, thereby minimizing the resulting uber JAR: <configuration> <minimizeJar>true</minimizeJar> ... </configuration> Note do not use this because some classes are used at run-time: NoClassDefFoundError: com/xuggle/ferry/JNIThreadProxy

<properties>
    <!-- Download the jar file classes and place into runnable jar. -->
    <maven-shade-plugin-version>3.1.1</maven-shade-plugin-version>
      <xuggle-groupId>xuggle</xuggle-groupId>
      <slf4j-groupId>org.slf4j</slf4j-groupId>
    
</properties>
<build>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>${maven-shade-plugin-version}</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <createSourcesJar>false</createSourcesJar>
                <minimizeJar>true</minimizeJar>
                <artifactSet>
                    <includes>
                        <include>${xuggle-groupId}:*</include>
                        <include>${slf4j-groupId}:*</include>
                    </includes>
                </artifactSet>

                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                  <mainClass>io.github.yash777.xuggler.VideoFrame</mainClass>
                </transformer>

                <!-- <relocations>
                    <relocation>
                        <pattern>org.eclipse.jetty</pattern>
                        <shadedPattern>org.seleniumhq.jetty7</shadedPattern>
                    </relocation>
                </relocations> -->
            </configuration>
        </execution>
    </executions>
</plugin>
</build>

Setting Manifest Entries with the ManifestResourceTransformer

The ManifestResourceTransformer allows existing entries in the MANIFEST to be replaced and new entries added.

For example, the following sample sets

  • the Main-Class entry to the value of the app.main.class property,
  • the X-Compile-Source-JDK entry to the value of the maven.compile.source property and
  • the X-Compile-Target-JDK entry to the value of the maven.compile.target property.
<transformers>
    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
      <manifestEntries>
        <Main-Class>${app.main.class}</Main-Class>
        <X-Compile-Source-JDK>${maven.compile.source}</X-Compile-Source-JDK>
        <X-Compile-Target-JDK>${maven.compile.target}</X-Compile-Target-JDK>
      </manifestEntries>
    </transformer>
</transformers>

Introduction to the Dependency Mechanism

  • System Dependencies
<dependency>
  <groupId>javax.sql</groupId>
  <artifactId>jdbc-stdext</artifactId>
  <version>2.0</version>
  <scope>system</scope>
  <systemPath>${java.home}/lib/rt.jar</systemPath>
      <!-- <systemPath>E://SeleniumWebDrivers.jar</systemPath>
      <systemPath>${project.basedir}/lib/iamajar.jar</systemPath> -->
</dependency>

  • Guide to installing 3rd party JARs

    Although rarely, but sometimes you will have 3rd party JARs that you need to put in your local repository for use in your builds, since they don't exist in any public repository like Maven Central.

mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> \
    -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>

https://stackoverflow.com/questions/4955635/how-to-add-local-jar-files-to-a-maven-project

mvn install:install-file
    -Dfile=awesomeapp-1.0.1.jar \
    -DpomFile=awesomeapp-1.0.1.pom \
    -Dsources=awesomeapp-1.0.1-sources.jar \
    -Djavadoc=awesomeapp-1.0.1-javadoc.jar \
    -DgroupId=com.example \
    -DartifactId=awesomeapp \
    -Dversion=1.0.1 \
    -Dpackaging=jar

Important note: This is marked deprecated.

Web Application with Executable Tomcat

<plugin>
    <groupId>org.apache.tomcat.maven</groupId>
    <artifactId>tomcat7-maven-plugin</artifactId>
    <version>2.0</version>
    <executions>
        <execution>
            <id>tomcat-run</id>
            <goals>
                <goal>exec-war-only</goal>
            </goals>
            <phase>package</phase>
            <configuration>
                <path>/</path>
                <enableNaming>false</enableNaming>
                <finalName>webappJar</finalName>
                <charset>utf-8</charset>
            </configuration>
        </execution>
    </executions>
</plugin>

To add resources files to Build.

<properties>
  <common.config.profile.directory>profileConfig/common</common.config.profile.directory>
  <config.profile.directory>profileConfig/dev</config.profile.directory>
</properties>

<build>
<resources>
  <resource>
    <directory>${config.profile.directory}</directory>
  </resource>
  <resource>
    <directory>${basedir}/src/main/resources</directory>
  </resource>
  <resource>
    <directory>src/main/resources</directory>
    <filtering>false</filtering>
  </resource>
</resources>
<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <configuration>
    <archiveClasses>true</archiveClasses>
    <classifier>${war.projectname.suffix}</classifier>
    <webResources>
      <resource> <!-- Common resources for all environments (OR) directly we can place in 
          resources folder -->
        <directory>${common.config.profile.directory}</directory>
        <targetPath>WEB-INF/classes</targetPath>
      </resource>
      <resource>
        <directory>${config.profile.directory}</directory>
        <targetPath>WEB-INF/classes</targetPath>
        <includes>
          <include>*.properties</include> <!-- **/**/*.properties -->
          <include>*.xml</include> <!-- context.xml : we can skip this -->
        </includes>
      </resource>
      <resource>
        <directory>${config.profile.directory}</directory>
        <targetPath>META-INF</targetPath>
        <includes>
          <include>ReadMe.txt</include>
          <include>context.xml</include>
        </includes>
      </resource>
    </webResources>
  </configuration>
</plugin>
</build>

In a class-based object-oriented language, in general, state is carried by instances, methods are carried by classes, and inheritance is only of structure and behavior. Basic, Refactoring Techniques

Method signature: It consists of method name and parameter list (number/type/order of the parameters). methodName(parametersList y). An instance method in a subclass with the same signature and return type as an instance method in the super-class overrides the super-class's method.

Java OOP concepts
Class  - Collection of a common features of a group of object [static/instance Fields, blocks and Methods]
Object - Instance of a class (instance fields)
Abstraction - Process of hiding complex info and providing required info like API, Marker Interfaces ...
Encapsulation(Security) - Class Binding up with data members(fields) and member functions.
Inheritance  (Reusability by placing common code in single class)
 1. Multilevel - {A -> B -> C} 2. Multiple - Diamond problem {A <- (B) -> C} [Java not supports] 3. Cyclic {A <-> B} [Java not supports]
 * Is-A   Relation - Class A extends B
 * Hash-A Relation - Class A { B obj = new B(); } - (Composition/Aggregation)
Polymorphism (Flexibility) 1. Compile-Time Overloading    2. Runtime Overriding  [Greek - "many forms"]


int[] arr = {1,2,3}; int arrLength = arr.length;   // Fixed length of sequential blocks to hold same data type
String str = "Yash"; int strLength = str.length(); // Immutable Object value can't be changed.

List<?> collections = new ArrayList<String>(); int collectionGroupSize = collections.size();
Map<?, ?> mapEntry = new HashMap<String, String>();
Set<?> keySet = mapEntry.keySet(); // Set of Key's
Set<?> entrySet = mapEntry.entrySet(); // Set of Entries [Key, Value]

// Immutable Objects once created they can't be modified. final class Integer/String/Employee
Integer val = Integer.valueOf("100"); String str2 = String.valueOf(100); // Immutable classes
final class Employee { // All Wrapper classes, java.util.UUID, java.io.File ...
    private final String empName; // Field as Final(values can be assigned only once) Only getter functions.
    public Employee(String name) { this.empName = name; }
}

Native Java Code for Hashtable.h, Hashtable.cpp SQL API.

You can check your current JDK and JRE versions on your command prompt respectively,

  • JDK javac -version [C:\Program Files\Java\jdk1.8.0_121\bin] o/p: javac 1.8.0_121
  • JRE java -version [C:\Program Files\Java\jdk1.8.0_121\bin] o/P: java version "1.8.0_102"

JAVA_HOME - Must be set to JDK otherwise maven projects leads to compilation error. [ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK? C:\Softwares\OpenJDK\, 7-zip

Fatal error compiling: invalid target release: JRE and JDK must be of same version 1.8.0.XXX

Disable TLS 1.0 and 1.1security-libs/javax.net.ssl: TLS 1.0 and 1.1 are versions of the TLS protocol that are no longer considered secure and have been superseded by more secure and modern versions (TLS 1.2 and 1.3).

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