Java开发小技巧（三）：Maven多工程依赖项目

project-monitor

下面以多可执行Jar包项目的开发为例，进行Maven多工程依赖项目开发的讲解。

首先来看一下封面图，我们要实现的效果是：

1.多个项目共享一个项目的类和方法等通用内容

2.每个子项目单独导入所需依赖，以及各自填充父项目配置文件中的占位符

3.子项目按指定目录结构进行打包

4.所有子项目集成打包到一个统一的目录，共享依赖包和配置文件等内容

5.打包后目录结构：

• bin：存放脚本文件，用来设置环境变量，执行相应的jar包
• lib：依赖、项目jar包
• etc：配置文件
• ......

好啦，目标明确的，接下来要进行具体开发实现了

打包配置

project-onepom.xml

<dependency>

    <groupId>com.demo</groupId>

    <artifactId>project-monitor</artifactId>

    <version>0.0.1</version>

</dependency>

maven-assembly-plugin

<plugin>

    <artifactId>maven-assembly-plugin</artifactId>

    <configuration>

        <appendAssemblyId>false</appendAssemblyId>

        <descriptors>

            <descriptor>package.xml</descriptor>

        </descriptors>

    </configuration>

    <executions>

        <execution>

            <id>make-assembly</id>

            <phase>package</phase>

            <goals>

                <goal>single</goal>

            </goals>

        </execution>

    </executions>

</plugin>

package.xml

<assembly 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/4.0.0http://maven.apache.org/xsd/assembly-1.0.0.xsd">

    <id>package</id>

    <formats>

        <format>zip</format>

    </formats>

    <includeBaseDirectory>true</includeBaseDirectory>
<fileSets>

        <fileSet>

            <directory>src/main/resources</directory>

            <includes>

                <include>*.properties</include>

                <include>*.xml</include>

            </includes>

            <outputDirectory>etc</outputDirectory>

        </fileSet>

    </fileSets>

    <dependencySets>

        <dependencySet>

            <outputDirectory>lib</outputDirectory>

            <scope>runtime</scope>

        </dependencySet>

    </dependencySets>

</assembly>

以上就实现了项目打包的配置工作，实现流程图中最后的项目结构，打包结果为zip文件

填充配置文件占位符

jdbc.properties

jdbc.driverClassName=com.mysql.jdbc.Driver

jdbc.url=jdbc:mysql://localdb:3306/test?characterEncoding=utf8&useSSL=true&serverTimezone=UTC

jdbc.username=root

jdbc.password=5EF28C5A9A0CE86C2D231A526ED5B388

PropertyPlaceholderConfigurer

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

    <property name="locations">

        <value>classpath:jdbc.properties</value>

    </property>

    <property name="ignoreResourceNotFound" value="false"/>

</bean>

Bingo，占位符修改完毕，别忘了引入父项目的上下文，毕竟我们要填充占位符的bean是在父项目中的：

<import resource="classpath*:project-monitor.xml"/>

测试Demo

DemoService

package com.demo.project.one.service;
import org.apache.log4j.Logger;
import javax.sql.DataSource;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;
public class DemoService {

    private static final Logger logger = Logger.getLogger(DemoService.class);

    private DataSource dataSource;
public void queryDb(){

        Connection conn = null;

        Statement stmt = null;

        ResultSet rs = null;
try {

            conn = dataSource.getConnection();

            stmt = conn.createStatement();

            rs = stmt.executeQuery("select * from movie limit 1");

            while(rs.next()){

                logger.info(String.format("Movie[Id=%d,Title=%s,Director=%s,Genre=%s,Language=%s]",

                        rs.getInt(1),

                        rs.getString(2),

                        rs.getString(3),

                        rs.getString(4),

                        rs.getString(5)

                        ));

            }

        } catch (SQLException e) {

            e.printStackTrace();

        } finally {

            try {

                if(rs != null){

                    rs.close();

                }

                if(stmt != null){

                    stmt.close();

                }

                if(conn != null){

                    conn.close();

                }

            } catch (SQLException e) {

                e.printStackTrace();

            }

        }

    }
public void setDataSource(DataSource dataSource) {

        this.dataSource = dataSource;

    }

}

在上下文中为其注入dataSource定义：

<bean id="demoService" class="com.demo.project.one.service.DemoService">

    <property name="dataSource" ref="dataSource"/>

</bean>

log4j.propertiesDemoService

package com.demo.project.one;
import com.demo.project.one.service.DemoService;

import org.springframework.context.ConfigurableApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Application {

    public static void main(String[] args){

        ConfigurableApplicationContext context = new ClassPathXmlApplicationContext("/project-one.xml");

        DemoService demoService = (DemoService)context.getBean("demoService");

        demoService.queryDb();

    }

}

最终的项目结构如图

打包

一切准备就绪，轮到项目打包了，在项目根目录执行以下Maven命令即可

mvn clean package

target

执行文件

binsetenv.batproject-one.batclasspath

setenv.bat

@echo off

set SRC_DIR=%cd%
cd %~dp0

cd ..

set MAIN_HOME=%cd%
cd %SRC_DIR%
set BIN_HOME=%MAIN_HOME%\bin

set ETC_HOME=%MAIN_HOME%\etc

set LIB_HOME=%MAIN_HOME%\lib

set CLASSPATH=%ETC_HOME%;%JAVA_HOME%\lib\tools.jar
for %%i in (%LIB_HOME%\*.jar) do set CLASSPATH=!CLASSPATH!;%%i

project-one.bat

@echo off

@setlocal enableextensions enabledelayedexpansion

call setenv.bat
chcp 65001

java -cp %CLASSPATH% com.demo.project.one.Application

pause

CLASSPATHproject-one-0.0.1.jar

运行

project-one.bat

bin

文章项目源码已发布到Github：https://github.com/ZKHDEV/MultDependPjo