Maven编译失败排查：拆分Spring Boot公共代码后找不到类

Here are the key steps to diagnose and fix your issue:

1. Confirm the Missing Class Exists in the Common Jar #

First, verify that the ExpressionToken class is actually present in the installed common jar. Run this command in your terminal:

jar tf ~/.m2/repository/com/beast-code/devops/prometheus-common/1.0.0/prometheus-common-1.0.0.jar | grep ExpressionToken

If this returns no results, the class wasn't packaged into the jar. You'll need to fix the common project's build configuration.

2. Fix the Common Project's Maven Packaging #

Your common project uses the spring-boot-maven-plugin, which is designed for building executable Spring Boot applications—not reusable libraries. Even with layout=NONE, it can alter the jar structure in unexpected ways. Replace it with the standard maven-jar-plugin:

In your common project's pom.xml, update the build section:

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-jar-plugin</artifactId>
      <version>3.3.0</version>
    </plugin>
  </plugins>
</build>

Then re-run mvn clean install on the common project to rebuild and reinstall the jar.

3. Double-Check Package Name Consistency #

Java package names cannot contain hyphens, so ensure:

• The ExpressionToken class in the common project is in the package com.beastcode.devops.prometheus.types (no hyphen in "beastcode").
• The import statement in your original project's ReferenceTreeAggregation.java matches exactly:

  import com.beastcode.devops.prometheus.types.ExpressionToken;
  

A mismatch here (even a single character) will cause the "cannot find symbol" error.

4. Force a Clean Rebuild of All Projects #

• On the common project:

  mvn clean install
  

• On the original project, force Maven to update dependencies and rebuild:

  mvn clean compile -U
  

The -U flag tells Maven to check for updated snapshots/releases, ensuring it picks up the latest version of your common jar.

5. Clear IDE Caches (If Using an IDE) #

IDEs like IntelliJ or Eclipse often cache Maven dependencies and compiled classes. Invalidate caches and restart your IDE to ensure it loads the latest version of the common jar:

• IntelliJ: File > Invalidate Caches... > Invalidate and Restart
• Eclipse: Project > Clean... > Clean all projects

6. Verify Dependency Scope #

Ensure the common dependency in your original project is set to compile scope (the default if not specified). Your current pom.xml looks correct here, but double-check that no accidental scope tag was added (like provided or test).

内容的提问来源于stack exchange，提问作者Joseph Gagnon