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JAVA搞不清楚系列 - Spring Boot Multi Module Porject

發表於 分類於

第一次碰到Multi Module其實應該是在做gRPC的專案的時候，後來才又重新認真研究了一下。
Spring Boot的Multi Module 可以幫助專案規劃分module，重複使用POM，以免引入變得過於龐大，且不用每次都構建整個專案，並且使得針對某個模組的特殊控制更為方便。

這篇文章是參考這個文章實作的：Spring Boot – Multi-Module Project

Gitlab連結

https://gitlab.com/jam68ty/spring-boot-multi-modules-semgrep

流程總覽

  1. 建立一個母moudule以及兩個子module
  2. 重構專案結構、產生jar檔
  3. 母module引入子moudule
  4. 寫一些測試的Service, Controller
  5. 此時應該要可以透過母module去控管整個專案共同需要的POM，而個別子module需要的dependency則在該module中引入即可

實作詳解

  1. 利用Maven Quickstart Archetype建立一個Parent Module
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    mvn archetype:generate -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4
  2. 用Spring Initializr建立兩個Child Modules，並把這兩個專案都移到Parent Module下
    a. jdjcore: 不引入任何dependency
    b. jdjweb: 引入Spring-web
  3. 完成後先mvn clean install 母Module
  4. 修改Parent Module的POM，引入兩個子Module
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    <?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.test</groupId>
      <artifactId>multi-module-project</artifactId>
      <version>1.0-SNAPSHOT</version>
    <!--  更改packaging的類型為pom-->
      <packaging>pom</packaging>   
      <name>multi-module-project</name>

      <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <java-version>1.8</java-version>
      </properties>

    <!--  引入子modules-->
      <modules>
        <module>jdj-core</module>
        <module>jdj-web</module>
      </modules>

      <dependencies>
        <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-test</artifactId>
          <version>2.3.6.RELEASE</version>
          <scope>test</scope>
        </dependency>
        <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter</artifactId>
          <version>2.3.6.RELEASE</version>
        </dependency>
      </dependencies>
    </project>
  5. 修改Child Module - jdjcore (包含Entity, DAO, Service)
  • POM
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    <?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>
    <!--  引入母modules-->
    	<parent>
    		<groupId>com.test</groupId>
    		<artifactId>multi-module-project</artifactId>
    		<version>1.0-SNAPSHOT</version>
    	</parent>
    	<artifactId>jdj-core</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>jdj-core</name>
    	<description>Demo project for Spring Boot</description>
    	<properties>
    		<java.version>1.8</java.version>
    	</properties>
    </project>
  • Entity: com.test.jdjcore.entity.Customer
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    package com.test.jdjcore.entity;

    public class Customer {

        private int id;
        private String name;
        private String email;

        public Customer() {
        }

        public Customer(int id, String name, String email) {
            this.id = id;
            this.name = name;
            this.email = email;

        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getEmail() {
            return email;
        }

        public void setEmail(String email) {
            this.email = email;
        }
    }
  • DAO: com.test.jdjcore.dao.CustomerRepository
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    package com.test.jdjcore.dao;

    import com.test.jdjcore.entity.Customer;

    public interface CustomerRepository {
        Customer getCustomerById(int id);
    }
  • Service: com.test.jdjcore.service.CustomerService
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    package com.test.jdjcore.service;

    import com.test.jdjcore.dao.CustomerRepository;
    import com.test.jdjcore.entity.Customer;
    import org.springframework.stereotype.Service;

    @Service("customerService")
    public class CustomerService implements CustomerRepository{

        @Override
        public Customer getCustomerById(int id) {
            return new Customer(id, "name", "email");
        }
    }
  • 把JdjCoreApplication的@SpringBootApplication註解掉，並把main的內容也刪除
  1. 修改Child Module - jdjweb (包含Controller)
  • POM
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    <?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>
    <!--  引入母modules-->
        <parent>
            <groupId>com.test</groupId>
            <artifactId>multi-module-project</artifactId>
            <version>1.0-SNAPSHOT</version>
        </parent>
        <artifactId>jdj-web</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>jdj-web</name>
        <description>Demo project for Spring Boot</description>
        <properties>
            <java.version>1.8</java.version>
        </properties>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
                <version>2.6.4</version>
            </dependency>

            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <version>2.6.4</version>
                <scope>test</scope>
            </dependency>
            <dependency>
            <groupId>com.test</groupId>
            <artifactId>jdj-core</artifactId>
                <version>0.0.1-SNAPSHOT</version>
            </dependency>
        </dependencies>

        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
            <finalName>javadev-web</finalName>
        </build>

    </project>
  • Controller: com.test.jdjweb.controller.CustomerController
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    package com.test.jdjweb.controller;

    import com.test.jdjcore.dao.CustomerRepository;
    import com.test.jdjcore.entity.Customer;
    import com.test.jdjcore.service.CustomerService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;

    @RestController
    @RequestMapping("")
    public class CustomerController {

        @Autowired
        CustomerService customerService;

        @GetMapping("/customer/{id}")
        public Customer getCustomer(@PathVariable int id){
            return customerService.getCustomerById(id);
        }

    }

    由於Multi-modules，@Autowierd可能會出錯，此時需要在JdjWebApplication.java加上@ComponentScan({”com.test.jdjcore”, “com.test.jdjweb”})

結果

  1. Start Application: 對整個專案mvn clean install → mvn spring-boot:run jdj-web
  2. Test: http://localhost:8080/customer/1