java - 为什么使用 maven- assembly-plugin 为多模块 Maven 项目创建的可执行 jar 显示 classnotfound 错误

Question

我正在尝试为我的多模块 Maven 项目创建一个可执行 jar。我使用 maven-assemble-plugin 生成 jar。即使我创建了 jar，但在尝试使用 java -jar 命令运行 jar 文件时遇到了 ClassNotFound 异常。

Answer 1

使用shade plugin ，比组装容易得多。

父 pom 将它们结合在一起:

<?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.greg</groupId>
  <artifactId>fat-jar</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>pom</packaging>

  <modules>
    <module>library-jar</module>
    <module>final-jar</module>
  </modules>

</project>

最终构建 jar pom，依赖于库:

<?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>
        <artifactId>fat-jar</artifactId>
        <groupId>com.greg</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <artifactId>final-jar</artifactId>

    <dependencies>
        <dependency>
            <groupId>com.greg</groupId>
            <artifactId>library-jar</artifactId>
            <version>${project.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>3.2.1</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer
                                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass>com.greg.App</mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>