Maven：自定义外部 jar 作为微服务架构的依赖项

Question

I am trying to create a microservices java project with springboot. My idea is to create a separate maven project which will contain all DTOs and utils classes common to all microservices. (I know many will criticize this choice but that's how I decided to proceed at the moment).

So I created the lib project and the base project. Working on the base project, my IDE can correctly read the classes contained in the lib module. During the compilation phase, i make a clean install of the lib project and then a clean install of the base project: at this point I get the following error:

[ERROR] symbol:   class Test
[ERROR] location: interface slt.mytest.base.services.TestsService
[ERROR] /C:/workspace/mytest/slt-base-be/src/main/java/slt/mytest/base/services/impl/TestsServiceImpl.java:[8,47] package slt.mytest.libs.entities.base does not exist
[ERROR] /C:/workspace/mytest/slt-base-be/src/main/java/slt/mytest/base/services/impl/TestsServiceImpl.java:[9,45] package slt.mytest.libs.models.base does not exist
[ERROR] /C:/workspace/mytest/slt-base-be/src/main/java/slt/mytest/base/repositories/TestsRepository.java:[5,47] package slt.mytest.libs.entities.base does not exist
[ERROR] /C:/workspace/mytest/slt-base-be/src/main/java/slt/mytest/base/repositories/TestsRepository.java:[10,60] cannot find symbol
[ERROR] symbol: class TestEntity

How can I make the lib a base project visible? Is there a way to automatically start compiling libs on every base install?

in general... how would you manage this case?

Thanks

lib project 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>2.6.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>slt.mytest</groupId>
    <artifactId>libs</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>libs</name>
    <description>Libs Module of mytest</description>
    <properties>
        <java.version>1.8</java.version>
        <org.mapstruct.version>1.2.0.Final</org.mapstruct.version>
        <org.projectlombok.version>1.18.22</org.projectlombok.version>
    </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>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
            <version>${org.projectlombok.version}</version>
        </dependency>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-jdk8</artifactId>
            <version>${org.mapstruct.version}</version>
        </dependency>


    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

base project 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>2.6.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>slt.mytest</groupId>
    <artifactId>base</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>base</name>
    <description>Base Module of mytest</description>
    <properties>
        <java.version>1.8</java.version>
        <org.mapstruct.version>1.2.0.Final</org.mapstruct.version>
        <org.projectlombok.version>1.18.22</org.projectlombok.version>
    </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>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
            <version>${org.projectlombok.version}</version>
        </dependency>
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-jdk8</artifactId>
            <version>${org.mapstruct.version}</version>
        </dependency>

        <dependency>
            <groupId>slt.mytest</groupId>
            <artifactId>libs</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

Answer 1

TL;DR: You may need to install your lib project to your local repository ( .m2/repository ). You can do this by executing mvn install (or use your IDE's GUI features) in the lib project. If base still does not compile, execute mvn dependency:resolve on base .

Your IDE may identify the dependency, and that is why there are no errors in your code editor, but Maven will not unless it can resolve the dependency. It will try to resolve from your local repository and remote repositories (which, in your case, since you have not defined any in your POM, is just Maven Central).