One of MAVEN study notes

1. Structure layering in development:

2, Several main links of the maven build process:

1. Cleanup : delete previous compilation results and prepare for recompilation
2. Compile : compile java source program into bytecode file
3. Test : Test the key points in the project to ensure the correctness of the key points in the iterative development process of the project.
4. Report : Record and display the test results in a standard format after each test
5. Packaging : Package a project containing many files into a compressed file for installation or deployment. The java project corresponds to the jar package, and the Web project corresponds to the war package;
6. Installation : In the Maven environment, it specifically refers to the installation of the packaged result-jar package or war into the local warehouse.
7. Deployment : Deploy the packaged result to the remote warehouse and deploy the war package to the server to run.

Maven builds the project automatically:

3, maven directory structure:

maven follows: convention> configuration> coding.

4, detailed explanation of pom.xml

    <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/4.0.0http://maven.apache.org/xsd/maven-4.0.0.xsd">
     
    	<!-- 模型版本。maven2.0必须是这样写，现在是maven2唯一支持的版本 -->
    	<modelVersion>4.0.0</modelVersion>
     
    	<!-- 公司或者组织的唯一标志，并且配置时生成的路径也是由此生成， 如com.winner.trade，maven会将该项目打成的jar包放本地路径：/com/winner/trade -->
    	<groupId>com.winner.trade</groupId>
     
    	<!-- 本项目的唯一ID，一个groupId下面可能多个项目，就是靠artifactId来区分的 -->
    	<artifactId>trade-core</artifactId>
     
    	<!-- 本项目目前所处的版本号 -->
    	<version>1.0.0-SNAPSHOT</version>
     
    	<!-- 打包的机制，如pom,jar, maven-plugin, ejb, war, ear, rar, par，默认为jar -->
    	<packaging>jar</packaging>
     
    	<!-- 帮助定义构件输出的一些附属构件,附属构件与主构件对应，有时候需要加上classifier才能唯一的确定该构件 不能直接定义项目的classifer,因为附属构件不是项目直接默认生成的，而是由附加的插件帮助生成的 -->
    	<classifier>...</classifier>
     
    	<!-- 定义本项目的依赖关系 -->
    	<dependencies>
     
    		<!-- 每个dependency都对应这一个jar包 -->
    		<dependency>
     
    			<!--一般情况下，maven是通过groupId、artifactId、version这三个元素值（俗称坐标）来检索该构件， 然后引入你的工程。如果别人想引用你现在开发的这个项目（前提是已开发完毕并发布到了远程仓库），--> 
    			<!--就需要在他的pom文件中新建一个dependency节点，将本项目的groupId、artifactId、version写入， maven就会把你上传的jar包下载到他的本地 -->
    			<groupId>com.winner.trade</groupId>
    			<artifactId>trade-test</artifactId>
    			<version>1.0.0-SNAPSHOT</version>
     
    			<!-- maven认为，程序对外部的依赖会随着程序的所处阶段和应用场景而变化，所以maven中的依赖关系有作用域(scope)的限制。 -->
    			<!--scope包含如下的取值：compile（编译范围）、provided（已提供范围）、runtime（运行时范围）、test（测试范围）、system（系统范围） -->
    			<scope>test</scope>
     
    			<!-- 设置指依赖是否可选，默认为false,即子项目默认都继承:为true,则子项目必需显示的引入，与dependencyManagement里定义的依赖类似  -->
    			<optional>false</optional>
     
    			<!-- 屏蔽依赖关系。 比如项目中使用的libA依赖某个库的1.0版，libB依赖某个库的2.0版，现在想统一使用2.0版，就应该屏蔽掉对1.0版的依赖 -->
    			<exclusions>
    				<exclusion>
    					<groupId>org.slf4j</groupId>
    					<artifactId>slf4j-api</artifactId>
    				</exclusion>
    			</exclusions>
     
    		</dependency>
     
    	</dependencies>
     
    	<!-- 为pom定义一些常量，在pom中的其它地方可以直接引用 使用方式 如下 ：${file.encoding} -->
    	<properties>
    		<file.encoding>UTF-8</file.encoding>
    		<java.source.version>1.5</java.source.version>
    		<java.target.version>1.5</java.target.version>
    	</properties>
     
    </project>

5. Connect to the private server warehouse

6, add WebContent

7, Reasons for mvn -install installation failure:

1. Either there is a problem with the path in eclipse and myeclipse;

2. Either the JDK in the POM.xml file does not match;

3. Either the JDK in the setting.xml in the Maven directory and the local .m2 local warehouse directory does not match the native JDK environment;

Of course, these three premises are based on the confirmation that the JDK environment is installed correctly, the environment variables have been configured correctly, and Maven is installed correctly.