This is a note for starting maven project from creating project to running application with configuration for external library dependencies.
Environment
- Mac OS Monterey 12.0
- Java 17.0.1 2021-10-19 LTS
- Apache Maven 3.8.3
1. Generate project structure
1
|
mvn archetype:generate -DgroupId=io.hommalab.app -DartifactId=multiplication-client -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4 -DinteractiveMode=false
|
This generates project structures as below:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
|
log4j-sample
├── pom.xml
└── src
├── main
│ └── java
│ └── io
│ └── hommalab
│ └── app
│ └── App.java
└── test
└── java
└── io
└── hommalab
└── app
└── AppTest.java
|
2. Add package dependency
As an example, adding log4j libraries.
pom.xml
1
2
3
4
5
6
7
8
9
10
11
12
|
<dependencies>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.14.1</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.14.1</version>
</dependency>
</dependencies>
|
Refs.
3. Update source code
Update main class using log4j like:
App.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
package io.hommalab.app;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class App
{
public static void main( String[] args )
{
Logger logger = LogManager.getLogger("Logger");
int ans = 4 * 5;
System.out.println( "Hello World!:" + ans );
logger.info(ans);
logger.warn("WARNING");
logger.error("ERROR");
}
}
|
4. Add definition for manifest file to pom.xml
Update pom.xml for adding classpath to external libraries.
- mainclass: Adding path to main class to execute by
java -jar xxx.jar command.
- addClasspath:
true for add classpath
- classpathPrefix: add
lib as a prefix directory in target ( libraries will be add in target/lib)
1
2
3
4
5
6
7
8
9
10
11
12
13
|
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<configuration>
<archive>
<manifest>
<mainClass>io.hommalab.app.App</mainClass>
<addClasspath>true</addClasspath>
<classpathPrefix>lib</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
|
5. Build package
5.1 mvn install package
Install and create package to target directory.
1
2
3
4
5
6
7
8
9
|
$ mvn clean install package
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.283 s
[INFO] Finished at: 2021-11-16T13:57:06+09:00
[INFO] ------------------------------------------------------------------------
|
This generates:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
arget
├── classes
│ └── io
│ └── hommalab
│ └── app
│ └── App.class
├── generated-sources
│ └── annotations
├── generated-test-sources
│ └── test-annotations
├── log4j-sample-1.0-SNAPSHOT.jar
├── maven-archiver
│ └── pom.properties
├── maven-status
│ └── maven-compiler-plugin
│ ├── compile
│ │ └── default-compile
│ │ ├── createdFiles.lst
│ │ └── inputFiles.lst
│ └── testCompile
│ └── default-testCompile
│ ├── createdFiles.lst
│ └── inputFiles.lst
├── surefire-reports
│ ├── TEST-io.hommalab.app.AppTest.xml
│ └── io.hommalab.app.AppTest.txt
└── test-classes
└── io
└── hommalab
└── app
└── AppTest.class
|
5.2. deploy external libraries to target
Retrieve META-INF/MANIFEST.MF to target.
1
|
jar xf target/log4j-sample-1.0-SNAPSHOT.jar META-INF/MANIFEST.MF
|
This generates META-INF/MANIFEST.MF
1
2
3
4
5
6
|
Manifest-Version: 1.0
Created-By: Apache Maven 3.8.3
Built-By: tato
Build-Jdk: 17.0.1
Class-Path: lib/log4j-api-2.14.1.jar lib/log4j-core-2.14.1.jar
Main-Class: io.hommalab.app.App
|
Copy dependencies to target/lib
1
|
mvn dependency:copy-dependencies -DoutputDirectory=target/lib -DincludeScope=compile
|
This generates:
1
2
3
|
target/lib
├── log4j-api-2.14.1.jar
└── log4j-core-2.14.1.jar
|
6. Run application
Run application:
1
2
3
|
java -jar target/log4j-sample-1.0-SNAPSHOT.jar
Hello World!:20
14:05:59.775 [main] ERROR Logger - ERROR
|
If you do not specify mainclass in META-INF/MANIFEST.MF in jar, running application by
java -cp target/log4j-sample-1.0-SNAPSHOT.jar io.hommalab.app.App
Warning
Cannot use log4j2.xml configuration in this project as of 16 November. Need to check how to add classpath for external configuration file.
Sources
github
References