用Maven给一个Maven工程打包，使用阿里云镜像解决mvn clean package出错的问题，使用plugin解决没有主清单属性的问题

本来在STS里做了一个极简Maven工程，内中只有一个Main方法的Java类，然后用新装的Maven3.6.3给它打包。

结果，Maven罢工，输出如下：

C:\personal\programs\ColoredText>mvn clean package
[INFO] Scanning for projects...
[INFO]
[INFO] -------------------------< com.hy:ColoredText >-------------------------
[INFO] Building ColoredText 0.0.1-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
Downloading from central: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  22.024 s
[INFO] Finished at: 2020-03-28T09:39:17+08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or one of its dependencies could not be resolved: Failed to read artifact descriptor for org.apache.maven.plugins:maven-clean-plugin:jar:2.5: Could not transfer artifact org.apache.maven.plugins:maven-clean-plugin:pom:2.5 from/to central (https://repo.maven.apache.org/maven2): Transfer failed for https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-clean-plugin/2.5/maven-clean-plugin-2.5.pom: Connect to repo.maven.apache.org:443 [repo.maven.apache.org/151.101.52.215] failed: Connection timed out: connect -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException

本着互联网就是知识库的理念，我开启了度娘查找模式，功夫不负有心人，在度娘的帮助下，短短几秒我就找到了解决方案：

  <mirrors>
     <!--配置阿里云maven私有仓库（即配阿里私服）-->
     <mirror>
         <id>alimaven</id>
         <mirrorOf>*</mirrorOf>
         <url>https://maven.aliyun.com/repository/central</url>
     </mirror>
  </mirrors>

上图深蓝色文字就是大招，把这段文字拷贝到Maven_HOME/conf/settings.xml(在我本机是C:\maven3.6.3\conf\settings.xml)里面的mirrors节点里就好了。

注意我是在家中电脑配置mirror节点，是不需要代理就能上网的环境，诸位如果公司电脑受限还需要设置代理，要不阿里云镜像还是访问不到。

之后再打包就一路绿灯了，输出一大堆文字，我截取了最后一部分贴出来：

us-interpolation-1.15.jar (0 B at 0 B/s)
Downloaded from alimaven: https://maven.aliyun.com/repository/central/org/codehaus/plexus/plexus-archiver/2.1/plexus-archiver-2.1.jar (0 B at 0 B/s)
Downloaded from alimaven: https://maven.aliyun.com/repository/central/org/apache/maven/maven-archiver/2.5/maven-archiver-2.5.jar (0 B at 0 B/s)
Downloaded from alimaven: https://maven.aliyun.com/repository/central/commons-lang/commons-lang/2.1/commons-lang-2.1.jar (0 B at 0 B/s)
[INFO] Building jar: C:\personal\programs\ColoredText\target\ColoredText-0.0.1-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  33.497 s
[INFO] Finished at: 2020-03-28T09:45:00+08:00
[INFO] ------------------------------------------------------------------------

然后，我兴致勃勃地准备运行程序，结果当头被浇一盆冷水：

C:\personal\programs\ColoredText>cd target

C:\personal\programs\ColoredText\target>java -jar ColoredText-0.0.1-SNAPSHOT.jar
ColoredText-0.0.1-SNAPSHOT.jar中没有主清单属性

我又在百度上查了一下，居然要我用winrar打开jar包修改Manifest.mf文件，添加“Main-class:类名”进去，这也太麻烦了，难道每次打出包来还要手动修改一次，没道理啊，于是我又在度娘的指引下找到了解决方案：

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.0.2</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <!-- 此处为程序主入口 -->
                            <mainClass>com.ufo.hy.EntryPoint</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>

上面蓝色部分就是解决方案，设置此段到pom.xml后，指定Main-class的任务将由Maven代行，如果你的pom.xml中没有build节点你需要把整段都拷贝过去。

再次打包执行，久违的hello world就出现在控制台了。

ompress-1.11.jar (426 kB at 91 kB/s)
[INFO] Building jar: C:\personal\programs\ColoredText\target\ColoredText-0.0.1-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  21.914 s
[INFO] Finished at: 2020-03-28T10:33:40+08:00
[INFO] ------------------------------------------------------------------------

C:\personal\programs\ColoredText>cd target

C:\personal\programs\ColoredText\target>java -jar ColoredText-0.0.1-SNAPSHOT.jar
Hello world!

C:\personal\programs\ColoredText\target>