maven - 如何在另一个项目中向Spring Boot Jar添加依赖项？

Question

我有一个Spring Boot应用程序，并由此创建了一个Jar。以下是我的pom.xml:

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
        <groupId>org.thymeleaf.extras</groupId>
        <artifactId>thymeleaf-extras-java8time</artifactId>
        <version>2.1.0.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <!-- WebJars -->
    <dependency>
        <groupId>javax.mail</groupId>
        <artifactId>mail</artifactId>
        <version>1.4.7</version>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.6.2</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

我想在其他应用程序中使用该Jar，因此将该jar添加到了我的应用程序中。但是，当我在那个Jar中调用方法时，它会抛出 ClassNotFoundException。

如何解决此问题？如何为Spring Boot JAR添加依赖项？

Answer 1

默认情况下，Spring Boot将您的JAR重新打包为可执行的JAR，并通过将您的所有类放入BOOT-INF/classes以及所有相关库放入BOOT-INF/lib来实现。创建此胖JAR的结果是您不能再将其用作其他项目的依赖项。

从Custom repackage classifier:

By default, the repackage goal will replace the original artifact with the repackaged one. That's a sane behaviour for modules that represent an app but if your module is used as a dependency of another module, you need to provide a classifier for the repackaged one.

The reason for that is that application classes are packaged in BOOT-INF/classes so that the dependent module cannot load a repackaged jar's classes.

如果要保留原始主要 Artifact 以将其用作依赖项，则可以在 classifier目标配置中添加 repackage :

<plugin>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-maven-plugin</artifactId>
  <version>1.4.1.RELEASE</version>
  <executions>
    <execution>
      <goals>
        <goal>repackage</goal>
      </goals>
      <configuration>
        <classifier>exec</classifier>
      </configuration>
    </execution>
  </executions>
</plugin>

通过这种配置，Spring Boot Maven插件将创建2个JAR:主要的将与通常的Maven项目相同，而第二个将附加分类器并成为可执行的JAR。