错误：无法找到或加载主类 Maven Spring Boot 应用程序 - 可执行 JAR

Question

I am trying to run an executable jar but got the following message :

Could not find or load main class

Here is the content of MANIFEST.MF file:

Manifest-Version: 1.0
Created-By: Apache Maven Built-By: Administrator
Build-Jdk: 11.0.3
Class-Path: spring-boot-starter-batch-2.2.0.RELEASE.jar spring-boot-starter-1.5.6.RELEASE.jar spring-boot-1.5.6.RELEASE.jar spring-boot-autocon
     figure-1.5.6.RELEASE.jar .......
Main-Class: EAB.ActiveTeam.Exporter.App

I am really stuck as I searched the web, tried many solutions to make my executable JAR run!

Please help, I sent over 5 hours trying to fix with no luck!

here is my POM.xml file:

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>EAB.ActiveTeam.Exporter</groupId>
    <artifactId>EAB.ActiveTeam.Exporter</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>EAB.ActiveTeam.Exporter</name>
    <description>EAB.ActiveTeam.Exporter</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

    <build>
        <plugins>
      <plugin>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
      <configuration>
        <mainClass>EAB.ActiveTeam.Exporter.App</mainClass>
        <layout>jar</layout>
        <outputDirectory>../libs</outputDirectory>
      </configuration>
        <executions>
          <execution>
            <id>repackage</id>
            <goals>
              <goal>repackage</goal>
            </goals>
            <configuration>
              <classifier>exec</classifier>
            </configuration>
          </execution>
        </executions>
      </plugin>
        </plugins>
    </build>
</project>

Answer 1

When it comes to spring boot application you can't create a regular jar file, because spring boot application jar is not a jar at all. It doesn't have an internal directory layout of jar (all dependencies are in BOOT-INF/lib for example) and there are some other subtle differences.

So I believe the issue is with maven here.

Instead of trying to create jar "by youself" and add all the dependencies there you should use spring boot maven plugin :

It "knows" how to create a spring boot jar properly. By default it will also resolve your "main" file (the one with method main and @SpringBootApplication annotation) however you can specify it in plugin configuration to be on the safe side.

Then you'll be able to the project with :

java -jar <Name_of_your_jar>