当多个项目之间有关联、依赖jar包有重复时，可以考虑进行合并。举例，我一开始有一个test-pilling项目，pom文件如下：
<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.wulinfeng.test</groupId> <artifactId>test-pilling</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>test-pilling</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>4.2.9.RELEASE</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.8.5</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.8.5</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.8.5</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-slf4j-impl</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-web</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.7.25</version> </dependency> <dependency> <groupId>org.apache.velocity</groupId> <artifactId>velocity</artifactId> <version>1.7</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.velocity</groupId> <artifactId>velocity-tools</artifactId> <version>2.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>commons-lang</groupId> <artifactId>commons-lang</artifactId> <version>2.6</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>4.2.9.RELEASE</version> <scope>compile</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> </dependencies> <build> <finalName>test-pilling</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <source>${maven.compiler.source}</source> <target>${maven.compiler.target}</target> <compilerArgs> <arg>-verbose</arg> <arg>-bootclasspath</arg> <arg>${env.JAVA_HOME}/jre/lib/rt.jar</arg> </compilerArgs> <showDeprecation>true</showDeprecation> <showWarnings>true</showWarnings> <debug>true</debug> <optimize>true</optimize> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <skip>true</skip> </configuration> </plugin> </plugins> </build> </project>
后来又搞了一个memcache-view项目，pom文件：
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.wulinfeng.memcache</groupId> <artifactId>memcache-view</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>memcache-view Maven Webapp</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>4.2.9.RELEASE</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>4.2.9.RELEASE</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.8.5</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.8.5</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.8.5</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-slf4j-impl</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-web</artifactId> <version>2.8</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.7.25</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.4</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.2</version> <scope>compile</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>4.2.9.RELEASE</version> <scope>compile</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <dependency> <groupId>com.googlecode.xmemcached</groupId> <artifactId>xmemcached</artifactId> <version>2.3.1</version> </dependency> <dependency> <groupId>org.asynchttpclient</groupId> <artifactId>async-http-client</artifactId> <version>2.1.0-alpha26</version> <exclusions> <exclusion> <artifactId>slf4j-api</artifactId> <groupId>org.slf4j</groupId> </exclusion> </exclusions> </dependency> </dependencies> <build> <finalName>memcache-view</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <source>${maven.compiler.source}</source> <target>${maven.compiler.target}</target> <compilerArgs> <arg>-verbose</arg> <arg>-bootclasspath</arg> <arg>${env.JAVA_HOME}/jre/lib/rt.jar</arg> </compilerArgs> <showDeprecation>true</showDeprecation> <showWarnings>true</showWarnings> <debug>true</debug> <optimize>true</optimize> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <skip>true</skip> </configuration> </plugin> </plugins> </build> </project>
我们发现这两个项目依赖的jar包很多都是一样的，比如springframe、log的一堆jar都是如出一辙的，现在我们建一个父pom文件来对这两个项目进行融合，剔除重复依赖的jar包，方便管理。新增一个maven项目，只保留pom文件，修改成：
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.wulinfeng</groupId> <artifactId>wireless-router</artifactId> <packaging>pom</packaging> <version>0.0.1-SNAPSHOT</version> <name>wireless-router Maven Webapp</name> <url>http://maven.apache.org</url> <modules> <module>test-pilling</module> <module>memcache-view</module> </modules> <properties> <junit.version>4.12</junit.version> <spring.version>4.3.11.RELEASE</spring.version> <jackson.version>2.8.5</jackson.version> <log.version>2.8</log.version> <slf4j.version>1.7.5</slf4j.version> <log.version>2.8</log.version> <servlet-api.version>3.1.0</servlet-api.version> </properties> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${spring.version}</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>${spring.version}</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>${jackson.version}</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>${jackson.version}</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>${jackson.version}</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> <version>${log.version}</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <version>${log.version}</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-slf4j-impl</artifactId> <version>${log.version}</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-web</artifactId> <version>${log.version}</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>${slf4j.version}</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>${servlet-api.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency>
</dependencies>
</dependencyManagement> </project>
修改test-pilling项目的pom文件，只需引入父pom的依赖即可，当然子项目自己用到的依赖需要自己引入，说白了就是继承关系：
<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> <parent> <groupId>com.wulinfeng</groupId> <artifactId>wireless-router</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <groupId>com.wulinfeng.test</groupId> <artifactId>test-pilling</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>test-pilling</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-slf4j-impl</artifactId> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-web</artifactId> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> </dependency> <dependency> <groupId>org.apache.velocity</groupId> <artifactId>velocity</artifactId> <version>1.7</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.velocity</groupId> <artifactId>velocity-tools</artifactId> <version>2.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>commons-lang</groupId> <artifactId>commons-lang</artifactId> <version>2.6</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <finalName>test-pilling</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <source>${maven.compiler.source}</source> <target>${maven.compiler.target}</target> <compilerArgs> <arg>-verbose</arg> <arg>-bootclasspath</arg> <arg>${env.JAVA_HOME}/jre/lib/rt.jar</arg> </compilerArgs> <showDeprecation>true</showDeprecation> <showWarnings>true</showWarnings> <debug>true</debug> <optimize>true</optimize> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <skip>true</skip> </configuration> </plugin> </plugins> </build> </project>
修改memcache-view项目的pom文件：
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>com.wulinfeng</groupId> <artifactId>wireless-router</artifactId> <version>0.0.1-SNAPSHOT</version> </parent> <groupId>com.wulinfeng.memcache</groupId> <artifactId>memcache-view</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>memcache-view Maven Webapp</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-slf4j-impl</artifactId> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-web</artifactId> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.4</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <scope>compile</scope> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>com.googlecode.xmemcached</groupId> <artifactId>xmemcached</artifactId> <version>2.3.1</version> </dependency> <dependency> <groupId>org.asynchttpclient</groupId> <artifactId>async-http-client</artifactId> <version>2.1.0-alpha26</version> <exclusions> <exclusion> <artifactId>slf4j-api</artifactId> <groupId>org.slf4j</groupId> </exclusion> </exclusions> </dependency> </dependencies> <build> <finalName>memcache-view</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.3</version> <configuration> <source>${maven.compiler.source}</source> <target>${maven.compiler.target}</target> <compilerArgs> <arg>-verbose</arg> <arg>-bootclasspath</arg> <arg>${env.JAVA_HOME}/jre/lib/rt.jar</arg> </compilerArgs> <showDeprecation>true</showDeprecation> <showWarnings>true</showWarnings> <debug>true</debug> <optimize>true</optimize> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <skip>true</skip> </configuration> </plugin> </plugins> </build> </project>
执行父项目的install会同时install两个子项目。