在控制台中从 maven 运行编译的 jar 时，我收到 java.lang.NoClassDefFoundError

Question

我昨天构建了一个 jar 文件（ mvn clean install ）并且它执行得很好，但是当我尝试构建一个 jar 文件时，它的构建没有错误，但占用的空间要小得多。 而且，当我尝试运行 jar 文件时，出现错误：

Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/SpringApplication
    at com.mukundmadhav.springboot.springboot.SpringbootApplication.main(SpringbootApplication.java:10)
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.SpringApplication

我的 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 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>2.2.4.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
</parent>
<groupId>com.mukundmadhav.springboot</groupId>
<artifactId>springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot</name>
<description>Demo project for Spring Boot</description>

<properties>
    <java.version>1.8</java.version>
    <start-class>com.mukundmadhav.springboot.springboot.SpringbootApplication</start-class>
</properties>

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

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </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>
    <pluginManagement>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>com.github.eirslett</groupId>
                <artifactId>frontend-maven-plugin</artifactId>
                <version>1.6</version>
                <configuration>
                    <workingDirectory>frontend</workingDirectory>
                    <installDirectory>target</installDirectory>
                </configuration>
                <executions>
                    <execution>
                        <id>install node and npm</id>
                        <goals>
                            <goal>install-node-and-npm</goal>
                        </goals>
                        <configuration>
                            <nodeVersion>v8.9.4</nodeVersion>
                            <npmVersion>5.6.0</npmVersion>
                        </configuration>
                    </execution>
                    <execution>
                        <id>npm install</id>
                        <goals>
                            <goal>npm</goal>
                        </goals>
                        <configuration>
                            <arguments>install</arguments>
                        </configuration>
                    </execution>
                    <execution>
                        <id>npm run build</id>
                        <goals>
                            <goal>npm</goal>
                        </goals>
                        <configuration>
                            <arguments>run build</arguments>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <artifactId>maven-antrun-plugin</artifactId>
                <executions>
                    <execution>
                        <phase>generate-resources</phase>
                        <configuration>
                            <target>
                                <copy todir="${project.build.directory}/classes/public">
                                    <fileset dir="${project.basedir}/frontend/build" />
                                </copy>
                            </target>
                        </configuration>
                        <goals>
                            <goal>run</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

        </plugins>
    </pluginManagement>
</build>

当我运行 mvn -v 时：

Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: C:\opt\apache-maven-3.6.3\bin\..
Java version: 1.8.0_171, vendor: Oracle Corporation, runtime: C:\Program Files\Java\jdk1.8.0_171\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

当我尝试从 Eclipse 运行应用程序时，该项目会运行。 我已经重新检查了我的系统变量和开始类的类路径。 我无法弄清楚问题是什么。

Answer 1

我想通了发生了什么。 我已经将我的插件包含在<pluginManagement/> ，因此它们没有被读取。 移除外壳解决了这个问题。