Maven-配置POM执行JAR

Question

I have a simple Hello World application 'App' which has been made in a Maven project. I'm aware that after building the project, the Maven assembly plugin is required in order to execute the JAR which is created when the project is built. I have followed the instructions found at:

http://maven.apache.org/plugins/maven-assembly-plugin/usage.html

But after editing my pom.xml and re-building the project, I still cannot run my JAR file.

Here is my pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany</groupId>
<artifactId>mini-project-6-ex6</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
</properties>
<build>
<plugins>
  <plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.5.4</version>
    <configuration>
      <descriptorRefs>
        <descriptorRef>jar-with-dependencies</descriptorRef>
      </descriptorRefs>
      <archive>
        <manifest>
          <mainClass>com.mycompany.mini.project.ex6.App</mainClass>
        </manifest>
      </archive>
    </configuration>
  </plugin>
</plugins>
</build>

Is there a mistake in my POM or additional lines which I have left out which is causing me to not be able to run the resulting JAR file?

EDIT: It seems as though the JAR has no manifest attribute (see comments). I suppose that I could open the jar using 7zip or similar program and manually add a manifest file, but the real question is how to create the JAR using Maven to include a manifest file in the first place.

Answer 1

You're looking at the wrong JAR. The POM above will create at least two JARs:

mini-project-6-ex6-1.0-SNAPSHOT.jar
mini-project-6-ex6-1.0-SNAPSHOT-jar-with-dependencies.jar

The former is only the code of the module, the latter is the code plus all the dependencies.

If you run mvn install , you will only get the first one since the Assembly Plugin isn't configured to run automatically. You can run it manually with mvn assembly:assembly .

If you want it to run automatically when you mvn install , you need to change the POM:

<plugins>
  <plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.5.4</version>
    <configuration>
      ...
    </configuration>
    <executions>
      <execution>
        <id>make-assembly</id> <!-- this is used for inheritance merges -->
        <phase>package</phase> <!-- bind to the packaging phase -->
        <goals>
          <goal>single</goal>
        </goals>
      </execution>
    </executions>
  </plugin>

See http://maven.apache.org/plugins/maven-assembly-plugin/usage.html#Execution:_Building_an_Assembly