maven 高级玩法

Posted 2021-12-01 hit-zb

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maven 高级玩法

标签（空格分隔）： maven

实用技巧

Maven 提速

多线程

# 用 4 个线程构建，以及根据 CPU 核数每个核分配 1 个线程进行构建
$ mvn -T 4 clean install
$ mvn -T 1C clean install

跳过测试

-DskipTests               # 不执行测试用例，但编译测试用例类生成相应的 class 文件至 target/test-classes 下
-Dmaven.test.skip=true    # 不执行测试用例，也不编译测试用例类

# 结合上文的`并行执行`
$ mvn -T 1C clean install -Dmaven.test.skip=true

# 如果还是阻塞: 资源管理器 - shutdown all java app

# 如果 jar 包过大，可以下载按照路径放在 repository 中，之后可能还需要 mvn clean 来下载 groovy-all-2.3.11.pom 文件 (mvnrepository.com)
D:\\apps\\maven\\repository\\org\\codehaus\\groovy\\groovy-all\\2.3.11\\groovy-all-2.3.11.jar

编译失败后，接着编译

# 如果是 Apache Eagle 之类带有几十个子项目的工程，如果从头编译所有的模块，会很耗功夫
# 通过指定之前失败的模块名，可以继续之前的编译
$ mvn -rf :moduleName clean install

跳过失败的模块，编译到最后再报错

$ mvn clean install --fail-at-end

使用 Nexus 本地私服

http://www.cnblogs.com/quanyongan/archive/2013/04/24/3037589.html

使用 Aliyun 国内镜像

可以大大提高编译下载速度

<mirror>
  <id>alimaven</id>
  <name>aliyun maven</name>
  <url>http://maven.aliyun.com/nexus/content/groups/public/</url>
  <mirrorOf>central</mirrorOf>
</mirror>

指定 Repository 目录

<!-- Default: ~/.m2/repository  -->
<localRepository>D:\\apps\\maven\\repository</localRepository>

如何使用 Maven 编译指定 module

$ mvn install -pl <module_name> -am

  -pl, --projects      (Build specified reactor projects instead of all project)
  -am, --also-make     (If project list is specified, also build projects required by the list)
  -amd, --also-make-dependents    (If project list is specified, also build projects that depend on)

Maven 标准目录结构

src/main/java             Application/Library sources
src/main/resources        Application/Library resources
src/main/filters          Resource filter files
src/main/webapp           Web application sources
src/test/java             Test sources
src/test/resources        Test resources
src/test/filters          Test resource filter files
src/it                    Integration Tests (primarily for plugins)
src/assembly              Assembly descriptors
src/site                  Site
LICENSE.txt               Project's license
NOTICE.txt                Notices and attributions required by libraries that the project depends on
README.txt                Project's readme

如何在 Maven 中使用多个 source

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>build-helper-maven-plugin</artifactId>
  <executions>
    <execution>
      <phase>generate-sources</phase>
      <goals>
        <goal>add-source</goal>
      </goals>
      <configuration>
        <sources>
          <source>src/main/scala</source>
        </sources>
      </configuration>
    </execution>
  </executions>
</plugin>

Using Scala UnitTest by Maven

安装 Scala

Maven 依赖

<dependency>
  <groupId>org.scalatest</groupId>
  <artifactId>scalatest_2.10</artifactId>
  <version>2.2.1</version>
</dependency>

创建 unittest 需要的 trait

import org.scalatest._
abstract class UnitTestStyle extends FlatSpec
with Matchers with OptionValues with Inside with Inspectors

编写测试

import spark.streaming.detect.SendNetflow
class SendNetflowTest extends UnitTestStyle {

  "Clean method" should "output a string" in {

    val s = "0,tcp,http,SF,229,9385,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,9,9,0.00,0.00,0.00,0.00,1.00,0.00,0.00,9,90,1.00,0.00,0.11,0.04,0.00,0.00,0.00,0.00,normal."
    SendNetflow.clean(s) should be("0,229,9385,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,9,9,0.00,0.00,0.00,0.00,1.00,0.00,0.00,9,90,1.00,0.00,0.11,0.04,0.00,0.00,0.00,0.00\\tnormal.")
  }

  it should "throw Exception if an empty string is inputted" in {
    val emptyS = ""
    a[RuntimeException] should be thrownBy {
    SendNetflow.clean(emptyS)
  }
}

Using slf4j by Maven

Maven 配置

<slf4j.version>1.7.12</slf4j.version>
<logback.version>1.1.3</logback.version>

<dependency>
  <groupId>ch.qos.logback</groupId>
  <artifactId>logback-core</artifactId>
  <version>${logback.version}</version>
</dependency>

<dependency>
  <groupId>ch.qos.logback</groupId>
  <artifactId>logback-classic</artifactId>
  <version>${logback.version}</version>
  <exclusions>
    <exclusion>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-core</artifactId>
    </exclusion>
    <exclusion>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </exclusion>
  </exclusions>
</dependency>

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-api</artifactId>
  <version>${slf4j.version}</version>
</dependency>

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>jcl-over-slf4j</artifactId>
  <version>${slf4j.version}</version>
  <exclusions>
    <exclusion>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </exclusion>
  </exclusions>
</dependency>

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>log4j-over-slf4j</artifactId>
  <version>${slf4j.version}</version>
  <exclusions>
    <exclusion>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </exclusion>
  </exclusions>
</dependency>

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>jul-to-slf4j</artifactId>
  <version>${slf4j.version}</version>
  <exclusions>
    <exclusion>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
    </exclusion>
  </exclusions>
</dependency>

logback.xml in resources directory

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <!-- %p:Level %m:Message %c.%M:Package+Method %F:%L:File+Line -->
  <property name="pattern" value="%d{yyyy-MM-dd HH:mm:ss.SSS} | %p | %m | %c.%M | %F:%L %n"/>

  <!-- Print in Console -->
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder charset="UTF-8">
    <pattern>${pattern}</pattern>
    </encoder>
  </appender>

  <root level="ALL">
    <appender-ref ref="STDOUT"/>
  </root>
</configuration>

编码

示例

private static final Logger log = LoggerFactory.getLogger(ZKEventWatch.class);
log.info(state);

遇到的坑

SLF4J multi bindings

遇到的坑

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/D:/apps/maven/repository/ch/qos/logback/logback-classic/1.1.3/logback-classic-1.1.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/D:/apps/maven/repository/org/slf4j/slf4j-log4j12/1.6.1/slf4j-log4j12-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]

解决

<!-- 使用 Apache Curator 需要 exclusion slf4j-log4j12，否则会出现问题 -->
<dependency>
  <groupId>org.apache.curator</groupId>
  <artifactId>curator-recipes</artifactId>
  <version>${apache.curator.version}</version>
  <exclusions>
    <exclusion>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
    </exclusion>
  </exclusions>
</dependency>

导出依赖 Jar

<build>
  <plugins>
    <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-dependency-plugin</artifactId>
    <version>2.10</version>
    <configuration>
      <outputDirectory>${project.build.directory}/lib</outputDirectory>
      <excludeTransitive>false</excludeTransitive>
      <stripVersion>false</stripVersion>
    </configuration>
    </plugin>
  </plugins>
</build>

$ mvn clean dependency:copy-dependencies

# 将 yuzhouwan-flume 依赖的 jars 都 导出到一个文件夹
# 用相对路径，不能是 绝对路径，否则 maven 会报错：Unknown lifecycle phase "Java"
$ mvn dependency:copy-dependencies -f yuzhouwan-flume/pom.xml -DoutputDirectory=yuzhouwan-flume/target/lib
$ mvn dependency:copy-dependencies -f yuzhouwan-api/yuzhouwan-admin-api/pom.xml -DoutputDirectory=target/lib

Profiles

日志级别

-Dorg.slf4j.simpleLogger.defaultLogLevel=error

Generate Code for Antlr

 mvn clean install -T 1C -DskipTests=true -Dorg.slf4j.simpleLogger.defaultLogLevel=error -B

Maven Properties

mvn clean install -Dmy.property=propertyValue

Maven Check Style

 mvn clean install -Dcheckstyle.skip

Maven Update

$ mvn clean install -U
# -U means force update of dependencies.

Maven License Check

参考http://code.mycila.com/license-maven-plugin/

Maven Dependency

Pre-download

$ mvn dependency:go-offline

Version-compare

# 在开发一些 Coprocessor 的时候，需要保证和 HBase 集群的依赖 jar 版本一致，可以使用该方法
$ mvn versions:compare-dependencies -DremotePom=org.apache.hbase:hbase:0.98.8-hadoop2 -DreportOutputFile=depDiffs.txt

Maven Proxy

命令行设置

# Linux (bash)
$ export MAVEN_OPTS="-DsocksProxyHost=10.10.10.10 -DsocksProxyPort=8080"
# Windows
$ set MAVEN_OPTS="-DsocksProxyHost=10.10.10.10 -DsocksProxyPort=8080"

配置文件 maven setting.xml

  <proxies>
    <!--<proxy>
      <id>http-proxy</id>
      <active>true</active>
      <protocol>http</protocol>
      <host>10.10.10.10</host>
      <port>8888</port>
      <nonProxyHosts>*.yuzhouwan.com</nonProxyHosts>
    </proxy>-->

    <proxy>
      <id>socks-proxy</id>
      <active>true</active>
      <protocol>socks5</protocol>
      <host>127.0.0.1</host>
      <port>1080</port>
      <nonProxyHosts>*.yuzhouwan.com</nonProxyHosts>
    </proxy>
  </proxies>

Avro 插件

创建 avsc 文件

{
  "namespace": "com.yuzhouwan.hacker.avro",
  "type": "record",
  "name": "User",
  "fields": [
    {
      "name": "name",
      "type": "string"
    },
    {
      "name": "favorite_number",
      "type": [
        "int",
        "null"
      ]
    },
    {
      "name": "favorite_color",
      "type": [
        "string",
        "null"
      ]
    }
  ]
}

使用 avro-tools 工具生成 Avro 类

# 下载 avro-tools
# https://mvnrepository.com/artifact/org.apache.avro/avro-tools/1.8.1
# http://archive.apache.org/dist/avro/avro-1.8.1/java/                    (better)
$ wget http://archive.apache.org/dist/avro/avro-1.8.1/java/avro-tools-1.8.1.jar -c avro-tools-1.8.1.jar

# 利用 avsc 文件中的 Schema 生成 Avro 类
$ java -jar avro-tools-1.8.1.jar compile schema user.avsc .

使用 avro-plugin 插件生成 Avro 类

<properties>
  <apache.avro.version>1.7.7</apache.avro.version>
</properties>

<dependencies>
  <!-- apache avro -->
  <dependency>
    <groupId>org.apache.avro</groupId>
    <artifactId>avro</artifactId>
    <version>${apache.avro.version}</version>
  </dependency>
</dependencies>

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.avro</groupId>
      <artifactId>avro-maven-plugin</artifactId>
      <version>${apache.avro.version}</version>
      <executions>
        <execution>
          <phase>generate-sources</phase>
          <goals>
            <goal>schema</goal>
          </goals>
          <configuration>
            <sourceDirectory>${project.basedir}/src/main/resources/avsc/</sourceDirectory>
            <outputDirectory>${project.basedir}/src/main/java/</outputDirectory>
          </configuration>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

Shade 插件解决 Jar 多版本共存

适用场景

在整合大型项目时，可能都依赖 commons-collections 此类的工具包，但是也可能 commons-collections 的版本却因为不一致，导致冲突。可以通过 Shade 插件的 relocation 方法进行重定向，此时冲突的依赖 package 名，会被重命名，并且依赖该 jar 的程序，都会被自动替换为新的 package 名

基本用法

实例一

<properties>
    <maven.shade.plugin.version>2.4.3</maven.shade.plugin.version>
</properties>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>2.4.3</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <shadedArtifactAttached>false</shadedArtifactAttached>
                <createSourcesJar>true</createSourcesJar>
                <artifactSet>
                    <excludes>
                        <exclude>org.mapdb.*</exclude>
                    </excludes>
                </artifactSet>
                <relocations>
                    <relocation>
                        <pattern>org.apache.commons.collections</pattern>
                        <shadedPattern>com.yuzhouwan.org.apache.commons.collections</shadedPattern>
                    </relocation>
                </relocations>
            </configuration>
        </execution>
    </executions>
</plugin>

实例二

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>${maven.shade.plugin.version}</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <shadedArtifactAttached>true</shadedArtifactAttached>
                <shadedClassifierName>all</shadedClassifierName>
                <createSourcesJar>true</createSourcesJar>
                <artifactSet>
                    <!-- 因为 org.glassfish 里面存在类似 public static class Builder implements javax.ws.rs.client.Invocation.Builder 全限定名的写法 -->
                    <!-- 所以只能用 shade 去隐藏 com.sun.jersey -->
                    <excludes>
                        <exclude>org.glassfish.*</exclude>
                    </excludes>
                </artifactSet>
                <relocations>
                    <relocation>
                        <pattern>javax.ws</pattern>
                        <shadedPattern>shade.javax.ws</shadedPattern>
                    </relocation>
                    <relocation>
                        <pattern>org.apache.curator</pattern>
                        <shadedPattern>shade.org.apache.curator</shadedPattern>
                    </relocation>
                    <!--<relocation>
                        <pattern>org.glassfish</pattern>
                        <shadedPattern>shade.org.glassfish</shadedPattern>
                    </relocation>
                    <relocation>
                        <pattern>com.sun.jersey</pattern>
                        <shadedPattern>shade.com.sun.jersey</shadedPattern>
                    </relocation>-->
                </relocations>
            </configuration>
        </execution>
    </executions>
</plugin>

通过 Shade 将问题解决后，部署上线后，依赖冲突复现

　因为官方明确指出 java.io.File.listFiles() 方法返回的文件序列顺序，是不做保证的。所以，上线后运行环境发生变化，加载 lib 目录下的 jar 包顺序，可能会发生变化。这时候，就需要利用不同 lib 目录，并修改 classpath 的方式，将 jar 包加载顺序确定下来

　例如，在整合 Druid 这类依赖树比较庞大的工程，就遇到了这么一种情况。Druid 中 com.sun.jersey (1.19) 和 Dataflow 中 org.glassfish.jersey (2.25.1) 发生冲突。增加了上述实例二中的 Shade 操作仍然会在线上环境，复现依赖冲突。这时，我们可以通过增加一个 lib_jersey 目录，存放 javax.ws.rs-api-2.1.jar，并修改 classpath 为 lib_jersey/*:lib/*。以此，保证了 lib_jersey 中的依赖得以优先加载，从而解决冲突

参考

http://maven.apache.org/plugins/maven-shade-plugin/

Assembly 插件

不同模块的依赖，打包到不同的目录下

具体步骤

第一步，先在负责打包分发的 distribution 模块中，设置 pom.xml 文件

<properties>
    <maven.assembly.plugin.version>2.3</maven.assembly.plugin.version>
</properties>

<packaging>pom</packaging>

<dependencies>
    <dependency>
        <groupId>com.yuzhouwan</groupId>
        <artifactId>core</artifactId>
    </dependency>
    <dependency>
        <groupId>com.yuzhouwan</groupId>
        <artifactId>ai</artifactId>
    </dependency>
    <dependency>
        <groupId>com.yuzhouwan</groupId>
        <artifactId>bigdata</artifactId>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <version>${maven.assembly.plugin.version}</version>
            <executions>
                <execution>
                    <id>assemble</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                    <configuration>
                        <descriptors>
                            <descriptor>src/assembly/bin.xml</descriptor>
                            <descriptor>src/assembly/src.xml</descriptor>
                        </descriptors>
                        <tarLongFileMode>gnu</tarLongFileMode>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

第二步，创建好对应的 bin.xml 和 src.xml

<assembly xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
          xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">

    <id>bin</id>

    <formats>
        <format>dir</format>
        <format>tar.gz</format>
    </formats>

    <baseDirectory>yuzhouwan-${project.version}-bin</baseDirectory>

    <fileSets>
        <fileSet>
            <directory>../</directory>

            <excludes>
                <exclude>**/target/**</exclude>
                <exclude>**/.classpath</exclude>
                <exclude>**/.project</exclude>
                <exclude>**/.settings/**</exclude>
                <exclude>lib/**</exclude>
                <exclude>conf/**</exclude>
            </excludes>

            <includes>
                <include>README</include>
                <include>LICENSE</include>
                <include>NOTICE</include>
                <include>CHANGELOG</include>
                <include>RELEASE-NOTES</include>
                <include>conf/</include>
            </includes>
        </fileSet>

        <fileSet>
            <directory>../</directory>
            <includes>
                <include>bin/yuzhouwan-cli.sh</include>
            </includes>
            <fileMode>0777</fileMode>
            <directoryMode>0755</directoryMode>
        </fileSet>
    </fileSets>

    <moduleSets>
        <moduleSet>
            <includeSubModules>false</includeSubModules>
            <useAllReactorProjects>true</useAllReactorProjects>
            <includes>
                <include>com.yuzhouwan:yuzhouwan-core</include>
            </includes>
            <excludes>
                <exclude>com.yuzhouwan:ai</exclude>
                <exclude>com.yuzhouwan:bigdata</exclude>
            </excludes>
            <binaries>
                <outputDirectory>lib/core</outputDirectory>
                <unpack>false</unpack>
                <dependencySets>
                    <dependencySet>
                        <useProjectArtifact>false</useProjectArtifact>
                        <useTransitiveDependencies>true</useTransitiveDependencies>
                        <unpack>false</unpack>
                        <excludes>
                            <exclude>com.yuzhouwan:ai</exclude>
                            <exclude>com.yuzhouwan:bigdata</exclude>
                        </excludes>
                    </dependencySet>
                </dependencySets>
            </binaries>
        </moduleSet>

        <moduleSet>
            <includeSubModules>false</includeSubModules>
            <useAllReactorProjects>true</useAllReactorProjects>
            <includes>
                <include>com.yuzhouwan:ai</include>
            </includes>
            <excludes>
                <exclude>com.yuzhouwan:bigdata</exclude>
            </excludes>
            <binaries>
                <outputDirectory>lib/plugins/ai</outputDirectory>
                <unpack>false</unpack>
                <dependencySets>
                    <dependencySet>
                        <useProjectArtifact>false</useProjectArtifact>
                        <useTransitiveDependencies>true</useTransitiveDependencies>
                        <unpack>false</unpack>
                        <excludes>
                            <exclude>com.yuzhouwan:bigdata</exclude>
                        </excludes>
                    </dependencySet>
                </dependencySets>
            </binaries>
        </moduleSet>

        <moduleSet>
            <includeSubModules>false</includeSubModules>
            <useAllReactorProjects>true</useAllReactorProjects>
            <includes>
                <include>com.yuzhouwan:bigdata</include>
            </includes>
            <excludes>
                <exclude>com.yuzhouwan:ai</exclude>
            </excludes>
            <binaries>
                <outputDirectory>lib/plugins/bigdata</outputDirectory>
                <unpack>false</unpack>
                <dependencySets>
                    <dependencySet>
                        <useProjectArtifact>false</useProjectArtifact>
                        <useTransitiveDependencies>true</useTransitiveDependencies>
                        <unpack>false</unpack>
                        <excludes>
                            <exclude>com.yuzhouwan:ai</exclude>
                        </excludes>
                    </dependencySet>
                </dependencySets>
            </binaries>
        </moduleSet>
    </moduleSets>
</assembly>

<assembly xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
          xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">

    <id>src</id>

    <formats>
        <format>dir</format>
        <format>tar.gz</format>
    </formats>

    <baseDirectory>yuzhouwan-${project.version}-src</baseDirectory>

    <fileSets>
        <fileSet>
            <directory>../</directory>

            <excludes>
                <exclude>**/target/**</exclude>
                <exclude>**/.classpath</exclude>
                <exclude>**/.project</exclude>
                <exclude>**/*.iml</exclude>
                <exclude>**/.settings/**</exclude>
                <exclude>lib/**</exclude>
            </excludes>

            <includes>
                <include>.ci</include>
                <include>.gitignore</include>
                <include>DEVNOTES</include>
                <include>README</include>
                <include>LICENSE</include>
                <include>NOTICE</include>
                <include>CHANGELOG</include>
                <include>RELEASE-NOTES</include>
                <include>bin/**</include>
                <include>conf/**</include>
                <include>native/**</include>
                <include>pom.xml</include>
                <include>dev-conf/**</include>
                <include>yuzhouwan-core/**</include>
                <include>yuzhouwan-ai/**</include>
                <include>yuzhouwan-bigdata/**</include>
            </includes>
        </fileSet>
    </fileSets>
</assembly>

构建完成之后，即可看到 yuzhouwan-ai 和 yuzhouwan-bigdata 模块的依赖，分别被打包到了 plugins/ai 和 plugins/bigdata 目录下

# 需要预先安装 tree 命令（yum install tree -y）
$ tree
  .
  ├── bin
  │   └── yuzhouwan-cli.sh
  └── lib
      ├── core
      └── plugins
          ├── ai
          └── bigdata

踩过的坑

模块间存在版本冲突的 jar 包
问题描述

Currently, inclusion of module dependencies may produce unpredictable results if a version conflict occurs

解决：
如果上述 yuzhouwan-ai 和 yuzhouwan-bigdata 模块，与 yuzhouwan-common 模块存在版本冲突的 jar 包，则需要将 bin.xml 拆解成 bin-common.xml、bin-ai.xml 和 bin-bigdata.xml 三个 assembly 配置文件，依次进行构建（此时需要将 id 设置成一样的，不然会被构建到不同的目录下）。否则，版本冲突的 jar 包，将只能保留其中一个版本，且具体保留哪个版本是不确定的

常见问题

Maven Archetype 的选择

Maven web 项目

选择 Archetype 的时候，选择 maven-archetype-webapp

其他语言编译出来的 Jar

Clojar

如果需要在 Maven 中，添加不是 Maven 中央仓库的 Repository，例如 Clojar：

<repositories>
  <repository>
    <id>clojars.org</id>
    <url>http://clojars.org/repo</url>
  </repository>
</repositories>

本地缓存

Maven 中出现 Repository 被缓存在本地，则可以添加下面属性

<repository>
  <id>clojars.org</id>
  <url>http://clojars.org/repo</url>
  <releases>
    <enabled>true</enabled>
    <updatePolicy>always</updatePolicy>
  </releases>
  <snapshots>
    <enabled>true</enabled>
    <updatePolicy>always</updatePolicy>
  </snapshots>
</repository>

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