如何向另一个项目中的 Spring Boot Jar 添加依赖项? [英] How to add a dependency to a Spring Boot Jar in another project?

问题描述

我有一个 Spring Boot 应用程序，我用它创建了一个 Jar.以下是我的pom.xml:

I have a Spring Boot application and I have created a Jar out of that. Following is my 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>

我想在我的其他应用程序中使用这个 Jar，所以将这个 jar 添加到我的应用程序中.但是当我在那个 Jar 中调用一个方法时，它会抛出一个 ClassNotFoundException.

I want to use this Jar in my other application so added this jar to my application. But when I am calling a method in that Jar, it is throwing a ClassNotFoundException.

我该如何解决这个问题?如何向 Spring Boot JAR 添加依赖项?

How can I fix this issue? How can I add a dependency to a Spring Boot JAR?

推荐答案

默认情况下，Spring Boot 将你的 JAR 重新打包成一个可执行的 JAR，它通过将你的所有类放在 BOOT-INF/classes，以及 BOOT-INF/lib 中的所有依赖库.创建这个胖 JAR 的后果是您不能再将它用作其他项目的依赖项.

By default, Spring Boot repackages your JAR into an executable JAR, and it does that by putting all of your classes inside BOOT-INF/classes, and all of the dependent libraries inside BOOT-INF/lib. The consequence of creating this fat JAR is that you can no longer use it as a dependency for other projects.

来自 自定义重新打包分类器:

默认情况下，repackage 目标将用重新打包的工件替换原始工件.对于代表应用的模块来说，这是一种理智的行为，但如果您的模块被用作另一个模块的依赖项，则您需要为重新打包的模块提供一个分类器.

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.

这样做的原因是应用程序类打包在BOOT-INF/classes 中，因此依赖模块无法加载重新打包的 jar 类.

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.

如果你想保留原来的 main artifact 以便将其用作依赖，你可以添加一个 classifier:

If you want to keep the original main artifact in order to use it as a dependency, you can add a classifier in the repackage goal configuration:

<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>

使用此配置，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.

With this configuration, the Spring Boot Maven Plugin will create 2 JARs: the main one will be the same as a usual Maven project, while the second one will have the classifier appended and be the executable JAR.

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