11-Maven环境下构建多模块项目【子模块打包错误解决方案】

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最新推荐文章于 2025-05-08 11:32:45 发布

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本文详细介绍了在Maven环境中创建包含parent、dao、service和controller四个模块的项目，包括配置pom.xml、模块间依赖以及解决打包时的错误。重点在于理解和应用Maven的多模块构建特性。

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Maven模块概述

使⽤maven 提供的多模块构建的特性完成maven 环境下多个模块的项⽬的管理与构建

这⾥以四个模块为例来搭建项⽬,以达到通俗易懂的初衷

模块 maven_parent —– 基模块,就是常说的parent （pom）

模块 maven_dao —– 数据库的访问层，例如jdbc操作（jar）模

块 maven_service —– 项⽬的业务逻辑层 （jar）

模块 maven_controller —– ⽤来接收请求，响应数据 （war）

项目模块之间的关系

maven_parent是三个子模块的父模块需要添加三个子模块的依赖
maven_dao用于数据库访问之类的数据处理需要提供给maven_service模块
maven_service接收maven_dao对数据处理的结果因此需要添加maven_dao模块的依赖
maven_controller需要接收请求并且与web网页进行连线因此需要构建的是web工程 并且添加maven_service的依赖

一、创建maven-parent项目及子模块

修改父模块和三个子模块的配置——pom.xml文件

maven_dao 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>maven_parent</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>maven_dao</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>maven_dao</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <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>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>

    </build>
</project>

maven_service 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>maven_parent</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>

    <modelVersion>4.0.0</modelVersion>

    <artifactId>maven_service</artifactId>
    <version>1.0-SNAPSHOT</version>

    <name>maven_service</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <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>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    <!--引入maven_dao模块的依赖-->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>maven_dao</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>


    </dependencies>

    <build>

    </build>
</project>

maven_controller 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>maven_parent</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>maven_controller</artifactId>
    <packaging>war</packaging>

    <name>maven_controller Maven Webapp</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <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>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <!--引入maven_service模块的依赖-->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>maven_service</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

        <!--    因为Controller层是web层 需要Servlet依赖    -->
        <!--    引入Servlet依赖     -->
        <dependency>
            <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

    <build>
        <finalName>maven_controller</finalName>
        <!-- 添加插件 -->
        <plugins>
            <!-- tomcat7插件 -->
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <!-- <port>8080</port> -->
                    <path>/web</path>
                    <uriEncoding>UTF-8</uriEncoding>
                    <server>tomcat7</server>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

maven_parent 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>maven_parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>maven_dao</module>
        <module>maven_service</module>
        <module>maven_controller</module>
    </modules>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

</project>

二、多模块依赖连接测试代码

maven_dao com.wedu.dao.UserDao

package com.wedu.dao;

public class UserDao {
    public static void testDao(){
        System.out.println("这是dao层的test");
    }
}

maven_service com.wedu.dao.UserService

package com.wedu.service;

import com.wedu.dao.UserDao;

public class UserService {
    public static void testService(){
        System.out.println("这是service层 test");
        //调用maven_dao模块的方法——这一步需要将dao模块的依赖引进
        UserDao.testDao();
    }
}

maven_controller com.wedu.dao.UserServlet

package com.wedu.controller;

import com.wedu.service.UserService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/user")
public class UserServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse reps) throws ServletException, IOException{
        System.out.println("UserServlet Test....");
        //调用maven_service模块的方法
        UserService.testService();
    }

}

添加运行配置
- 将各个模块都先打包——jar包/war包
  因为进行打包后仓库中才有记录，之前配置的依赖才会有效
tamcat7:run 启动
结果：

复制网址后再浏览器打开在连接末尾输入在controller模块设置的 “user”
控制台会显示调用各模块方法的打印结果

三、子模块打包错误！！

目录结构

问题：先打包UserDao —— build success
再打包UserService，此时出错！错误信息如下

Failed to execute goal on project maven_service: Could not resolve dependencies for project org.example:maven_service:jar:1.0-SNAPSHOT: Failed to collect dependencies at org.example:maven_dao:jar:1.0-SNAPSHOT