java - 如何解决 Spring Boot 无法找到或加载主类错误？

Question

我为 Spring Boot 创建了一个 Maven 项目。我有很多 Spring 依赖项和一个主类:

package com.vastserver;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MyArtifactApplication {

    public static void main(String[] args) {

//      SpringApplication.run(MyArtifactApplication.class, args);
        System.out.println("hello!");
    }

}

src目录的文件夹结构为:

.
└── main
    ├── java
    │   └── com
    │       └── vastserver
    │           └── MyArtifactApplication.java
    └── resources
        └── application.properties

在我的 pom.xml 中，我使用 maven-assemble-plugin 来在独立的 .jar 文件中构建我的项目。即使我三次检查了目录结构和主类文件是否正确显示在 pom.xml 中，我仍然收到错误: Error: Could not find or load main class com.vastserver.MyArtifactApplication 当我运行时mvn package，然后 java -cp target/vast-ad-server-artifactId-1.0-SNAPSHOT-jar-with-dependency.jar com.vastserver.MyArtifactApplication 或 mvn exec:exec。如果我从 Intellij 运行主类，它确实可以工作，所以我知道代码不是问题，而是 Maven build设置。我不知道问题出在哪里。

我的 pom.xml 如下所示:

<?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>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <maven.compiler.release>11</maven.compiler.release>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <mainClass>com.vastserver.MyArtifactApplication</mainClass>
        <descriptorRef>jar-with-dependencies</descriptorRef>
        <targetSnapshot>target/vast-ad-server-artifactId-1.0-SNAPSHOT</targetSnapshot>
        <targetWithDependencies>${targetSnapshot}-${descriptorRef}.jar</targetWithDependencies>
    </properties>

    <groupId>com.vastserver</groupId>
    <artifactId>vast-ad-server-artifactId</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-activemq</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                        <configuration>
                            <archive>
                                <manifest>
                                    <mainClass>${mainClass}</mainClass>
                                </manifest>
                            </archive>
                            <descriptorRefs>
                                <descriptorRef>${descriptorRef}</descriptorRef>
                            </descriptorRefs>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.3.2</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>exec</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <executable>java</executable>
                    <arguments>
                        <argument>-cp</argument>
                        <argument>${targetWithDependencies}</argument>
                        <argument>${mainClass}</argument>
                    </arguments>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

对我来说:Maven - 更新项目有效。