对于maven, 很多人看似很熟悉,其实貌似根本不了解,本文旨在解决某些方面的疑惑。
当我在service模块引入公司某业务的一个接口,由于该接口依赖了公司写的各种东西和spring等第三方依赖,所以我一下子啥都不用显示依赖了,这叫传递性。而dependencyManagement的作用在于仍然让子模块显示写依赖,但依赖的版本和设置不用写了,简化了。关于jar包的传递依赖,你可以在idea的maven窗口中选定子模块右键show dependencies。
在idea环境中,有时你不得不执行reimport和clean,才能看到jar包引入。另外,请注意你写的version是仓库中确实存在的。
如果公司没有maven私服,完全依赖apache maven库,也许是够用的,碰到其他公司的接口需要你引入他们的jar包时,可以把jar包放在jvm/ext/lib下。
值得一提的是,在模块组织方面,你完全可以把紧密相关的几个系统的放在一起,各个系统的web模块公用一套common, do及dao模块,而不必为每个系统打开一个idea窗口。
pom里已经引入dependency,但很多时候我们需要reimport一下甚至很多下才能看到jar包被真正引入,如果module被ignore了,那么也很可能引入不了jar包。注意,只要dependency没变红,就是OK的。
本地install时,请把当前模块依赖的模块先install一下。
本地测试时,idea开启了自动indexing时,很有可能远程的包会覆盖本地的包,导致本地要重新install。
maven的传递性依赖会导致间接进入一些包而与显示引入的发生冲突,例如,某依赖间接引入了spring2.5.6,模块里显示依赖的是spring3.1.1,spring2.5.6里ThreadPoolTaskExecutor没有submit(Runnable)方法,spring3.1.1里有,程序运行时极有可能加载spring2.5.6的ThreadPoolTaskExecutor.class而发生java.lang.NoSuchMethodError。
maven其他注意点:
由于历史原因,maven的核心插件之一——compiler插件默认只支持编译Java 1.3,因此需要配置该插件使其支持Java 5.
典型的maven配置示例:
父pom
- <?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.ixhong</groupId>
- <artifactId>ixhong</artifactId>
- <packaging>pom</packaging>
- <version>1.0-SNAPSHOT</version>
- <modules>
- <module>ixhong-common</module>
- <module>ixhong-admin-web</module>
- <module>ixhong-domain</module>
- <module>ixhong-dao</module>
- <module>ixhong-manager</module>
- <module>ixhong-fs-web</module>
- <module>ixhong-support-web</module>
- <module>ixhong-lender-web</module>
- <module>ixhong-base</module>
- <module>ixhong-tomcat-web</module>
- </modules>
- <properties>
- <spring.version>3.2.11.RELEASE</spring.version>
- <ibatis.version>3.2.7</ibatis.version>
- <rootdir>${basedir}</rootdir>
- </properties>
- <dependencies>
- <dependency>
- <groupId>commons-lang</groupId>
- <artifactId>commons-lang</artifactId>
- <version>2.6</version>
- </dependency>
- <dependency>
- <groupId>commons-collections</groupId>
- <artifactId>commons-collections</artifactId>
- <version>3.2.1</version>
- </dependency>
- <dependency>
- <groupId>commons-codec</groupId>
- <artifactId>commons-codec</artifactId>
- <version>1.10</version>
- </dependency>
- <!-- -->
- <dependency>
- <groupId>log4j</groupId>
- <artifactId>log4j</artifactId>
- <version>1.2.12</version>
- </dependency>
- </dependencies>
- <dependencyManagement>
- <dependencies>
- <dependency>
- <groupId>javax.servlet</groupId>
- <artifactId>javax.servlet-api</artifactId>
- <version>3.0.1</version>
- <scope>provided</scope>
- </dependency>
- <dependency>
- <groupId>redis.clients</groupId>
- <artifactId>jedis</artifactId>
- <version>2.8.0</version>
- </dependency>
- <dependency>
- <groupId>org.apache.struts</groupId>
- <artifactId>struts2-core</artifactId>
- <version>2.2.3.1</version>
- </dependency>
- <dependency>
- <groupId>org.apache.tomcat</groupId>
- <artifactId>tomcat-catalina</artifactId>
- <version>7.0.57</version>
- <scope>provided</scope>
- </dependency>
- <dependency>
- <groupId>org.apache.tomcat</groupId>
- <artifactId>tomcat-coyote</artifactId>
- <version>7.0.57</version>
- <scope>provided</scope>
- </dependency>
- </dependencies>
- </dependencyManagement>
- <!--<scm>
- <connection>scm:git:git@git.qwexyz.com:qwexyz/qwexyz.git</connection>
- <url>scm:git:git@git.qwexyz.com:qwexyz/qwexyz.git</url>
- <developerConnection>scm:git:git@git.qwexyz.com:qwexyz/qwexyz.git</developerConnection>
- </scm>-->
- <build>
- <plugins>
- <plugin>
- <artifactId>maven-compiler-plugin</artifactId>
- <version>3.1</version>
- <configuration>
- <source>1.6</source>
- <target>1.6</target>
- <encoding>UTF-8</encoding>
- </configuration>
- </plugin>
- <plugin>
- <artifactId>maven-resources-plugin</artifactId>
- <version>2.6</version>
- <configuration>
- <encoding>UTF-8</encoding>
- </configuration>
- </plugin>
- <plugin>
- <groupId>org.apache.maven.plugins</groupId>
- <artifactId>maven-release-plugin</artifactId>
- <version>2.1</version>
- </plugin>
- </plugins>
- </build>
- </project>
web
- <?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>ixhong</artifactId>
- <groupId>com.ixhong</groupId>
- <version>1.0-SNAPSHOT</version>
- </parent>
- <modelVersion>4.0.0</modelVersion>
- <artifactId>ixhong-lender-web</artifactId>
- <packaging>war</packaging>
- <name>ixhong-user-web</name>
- <url>http://maven.apache.org</url>
- <!-- 依赖包 -->
- <dependencies>
- <dependency>
- <groupId>com.ixhong</groupId>
- <artifactId>ixhong-manager</artifactId>
- <version>1.0-SNAPSHOT</version>
- </dependency>
- <dependency>
- <groupId>com.ixhong</groupId>
- <artifactId>ixhong-common</artifactId>
- <version>1.0-SNAPSHOT</version>
- </dependency>
- <dependency>
- <groupId>org.mybatis</groupId>
- <artifactId>mybatis-spring</artifactId>
- <version>1.2.2</version>
- </dependency>
- <dependency>
- <groupId>org.springframework</groupId>
- <artifactId>spring-context</artifactId>
- <version>${spring.version}</version>
- </dependency>
- <dependency>
- <groupId>org.springframework</groupId>
- <artifactId>spring-context-support</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-jdbc</artifactId>
- <version>${spring.version}</version>
- </dependency>
- <dependency>
- <groupId>mysql</groupId>
- <artifactId>mysql-connector-java</artifactId>
- <version>5.1.32</version>
- </dependency>
- <dependency>
- <groupId>org.apache.velocity</groupId>
- <artifactId>velocity</artifactId>
- <version>1.7</version>
- </dependency>
- <dependency>
- <groupId>javax.servlet</groupId>
- <artifactId>javax.servlet-api</artifactId>
- <version>3.0.1</version>
- <scope>provided</scope>
- </dependency>
- <dependency>
- <groupId>commons-dbcp</groupId>
- <artifactId>commons-dbcp</artifactId>
- <version>1.4</version>
- </dependency>
- <dependency>
- <groupId>commons-fileupload</groupId>
- <artifactId>commons-fileupload</artifactId>
- <version>1.3.1</version>
- </dependency>
- <dependency>
- <groupId>org.apache.velocity</groupId>
- <artifactId>velocity-tools</artifactId>
- <version>2.0</version>
- <exclusions>
- <exclusion>
- <groupId>org.apache.struts</groupId>
- <artifactId>*</artifactId>
- </exclusion>
- </exclusions>
- </dependency>
- <dependency>
- <groupId>org.apache.activemq</groupId>
- <artifactId>activemq-client</artifactId>
- <version>5.11.1</version>
- </dependency>
- <dependency>
- <groupId>org.springframework</groupId>
- <artifactId>spring-jms</artifactId>
- <version>${spring.version}</version>
- </dependency>
- <dependency>
- <groupId>org.springframework</groupId>
- <artifactId>spring-test</artifactId>
- <version>${spring.version}</version>
- <scope>test</scope>
- </dependency>
- <dependency>
- <groupId>junit</groupId>
- <artifactId>junit</artifactId>
- <version>4.8.2</version>
- <scope>test</scope>
- </dependency>
- </dependencies>
- <build>
- <finalName>ROOT</finalName>
- <outputDirectory>src/main/webapp/WEB-INF/classes</outputDirectory>
- <resources>
- <resource>
- <directory>src/main/resources</directory>
- <filtering>true</filtering>
- </resource>
- </resources>
- </build>
- <profiles>
- <profile>
- <id>development</id>
- <activation>
- <activeByDefault>true</activeByDefault>
- </activation>
- <build>
- <filters>
- <filter>../profile/development.properties</filter>
- </filters>
- </build>
- </profile>
- <profile>
- <id>test</id>
- <build>
- <filters>
- <filter>../profile/test.properties</filter>
- </filters>
- </build>
- </profile>
- <profile>
- <id>production</id>
- <build>
- <filters>
- <filter>../profile/production.properties</filter>
- </filters>
- </build>
- </profile>
- </profiles>
- </project>
dao
- <?xml version="1.0" encoding="UTF-8"?>
- <project xmlns="http://maven.apache.org/POM/4.0.0"
- xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
- xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
- <parent>
- <artifactId>ixhong</artifactId>
- <groupId>com.ixhong</groupId>
- <version>1.0-SNAPSHOT</version>
- </parent>
- <modelVersion>4.0.0</modelVersion>
- <artifactId>ixhong-dao</artifactId>
- <packaging>jar</packaging>
- <name>ixhong-dao</name>
- <url>http://maven.apache.org</url>
- <build>
- <finalName>ixhong-dao</finalName>
- <resources>
- <resource>
- <directory>src/main/resources</directory>
- <filtering>true</filtering>
- </resource>
- </resources>
- </build>
- <dependencies>
- <dependency>
- <groupId>com.ixhong</groupId>
- <artifactId>ixhong-domain</artifactId>
- <version>1.0-SNAPSHOT</version>
- </dependency>
- <dependency>
- <groupId>org.mybatis</groupId>
- <artifactId>mybatis</artifactId>
- <version>${ibatis.version}</version>
- </dependency>
- </dependencies>
- </project>
domain
- <?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>ixhong</artifactId>
- <groupId>com.ixhong</groupId>
- <version>1.0-SNAPSHOT</version>
- </parent>
- <modelVersion>4.0.0</modelVersion>
- <artifactId>ixhong-domain</artifactId>
- <packaging>jar</packaging>
- <name>ixhong-domain</name>
- <url>http://maven.apache.org</url>
- <build>
- <finalName>ixhong-domain</finalName>
- </build>
- <dependencies>
- <dependency>
- <groupId>net.sf.json-lib</groupId>
- <artifactId>json-lib</artifactId>
- <version>2.4</version>
- <classifier>jdk15</classifier>
- </dependency>
- </dependencies>
- </project>
maven的核心仅仅定义了抽象的生命周期,具体的任务是交由插件完成的,插件以独立的构建形式存在,因此,maven核心的分发包只有不到3MB的大小,Maven会在需要的时候下载并使用插件。一个插件可能会对应多个目标,一个目标就是一个功能,如maven-dependency-plugin有十多个目标,dependency:analyze,dependency:tree,dependency:list等。
可以使用jetty-maven-plugin启动web应用进行测试。
配置文件
settings.xml中的profile是pom.xml中的profile的简洁形式。它包含了激活(activation),仓库(repositories),插件仓库(pluginRepositories)和属性(properties)元素。profile元素仅包含这四个元素是因为他们涉及到整个的构建系统,而不是个别的POM配置。
如果settings中的profile被激活,那么它的值将重载POM或者profiles.xml中的任何相等ID的profiles。
激活(activation)
activations是profile的关键,就像POM中的profiles,profile的能力在于它在特定情况下可以修改一些值。而这些情况是通过activation来指定的。
- <?xml version="1.0" encoding="UTF-8"?>
- <settings xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd" xmlns="http://maven.apache.org/SETTINGS/1.0.0"
- xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
- <profiles>
- <profile>
- <repositories>
- <repository>
- <snapshots>
- <enabled>false</enabled>
- </snapshots>
- <id>central</id>
- <name>libs-releases</name>
- <url>http://maven.whatsmars.com/libs-releases</url>
- </repository>
- <repository>
- <snapshots />
- <id>snapshots</id>
- <name>libs-snapshots</name>
- <url>http://maven.whatsmars.com/libs-snapshots</url>
- </repository>
- </repositories>
- <pluginRepositories>
- <pluginRepository>
- <snapshots>
- <enabled>false</enabled>
- </snapshots>
- <id>central</id>
- <name>plugins-releases</name>
- <url>http://maven.whatsmars.com/plugins-releases</url>
- </pluginRepository>
- <pluginRepository>
- <snapshots />
- <id>snapshots</id>
- <name>plugins-snapshots</name>
- <url>http://maven.whatsmars.com/plugins-snapshots</url>
- </pluginRepository>
- </pluginRepositories>
- <id>artifactory</id>
- </profile>
- </profiles>
- <activeProfiles>
- <activeProfile>artifactory</activeProfile>
- </activeProfiles>
- </settings>
mvn package-DskipTests 打包并且跳过测试
mvn clean install-Pdev 激活dev下的profile,这样properties中的配置就会替换成实际值
maven可继承的pom元素
- groupId :项目组 ID ,项目坐标的核心元素;
- version :项目版本,项目坐标的核心元素;
- description :项目的描述信息;
- organization :项目的组织信息;
- inceptionYear :项目的创始年份;
- url :项目的 url 地址
- develoers :项目的开发者信息;
- contributors :项目的贡献者信息;
- distributionManagerment :项目的部署信息;
- issueManagement :缺陷跟踪系统信息;
- ciManagement :项目的持续继承信息;
- scm :项目的版本控制信息;
- mailingListserv :项目的邮件列表信息;
- properties :自定义的 Maven 属性;
- dependencies :项目的依赖配置;
- dependencyManagement :醒目的依赖管理配置;
- repositories :项目的仓库配置;
- build :包括项目的源码目录配置、输出目录配置、插件配置、插件管理配置等;
- reporting :包括项目的报告输出目录配置、报告插件配置等。