Maven基礎：創建示例項目

使用mvn archetype:generate可以創建示例項目，這篇文章maven的基礎使相關的命令行創建項目進行簡單的示例說明。

環境

liumiaocn:maven liumiao$ mvn -version
Apache Maven 3.5.4 (1edded0938998edf8bf061f1ceb3cfdeccf443fe; 2018-06-18T02:33:14+08:00)
Maven home: /Library/Maven/apache-maven-3.5.4
Java version: 1.8.0_191, vendor: Oracle Corporation, runtime: /Library/Java/JavaVirtualMachines/jdk1.8.0_191.jdk/Contents/Home/jre
Default locale: en_CN, platform encoding: UTF-8
OS name: "mac os x", version: "10.15.4", arch: "x86_64", family: "mac"
liumiaocn:maven liumiao$

創建示例項目

liumiaocn:maven liumiao$ ls
liumiaocn:maven liumiao$ mvn archetype:generate -DgroupId=com.liumiao -DartifactId=helloprj
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO] 
[INFO] >>> maven-archetype-plugin:3.1.2:generate (default-cli) > generate-sources @ standalone-pom >>>
[INFO] 
[INFO] <<< maven-archetype-plugin:3.1.2:generate (default-cli) < generate-sources @ standalone-pom <<<
[INFO] 
[INFO] 
[INFO] --- maven-archetype-plugin:3.1.2:generate (default-cli) @ standalone-pom ---
[INFO] Generating project in Interactive mode
[INFO] No archetype defined. Using maven-archetype-quickstart (org.apache.maven.archetypes:maven-archetype-quickstart:1.0)
Choose archetype:
...
2721: remote -> za.co.absa.hyperdrive:component-archetype (-)
Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): 1615: 
Choose org.apache.maven.archetypes:maven-archetype-quickstart version: 
1: 1.0-alpha-1
2: 1.0-alpha-2
3: 1.0-alpha-3
4: 1.0-alpha-4
5: 1.0
6: 1.1
7: 1.3
8: 1.4
Choose a number: 8: 8
[INFO] Using property: groupId = com.liumiao
[INFO] Using property: artifactId = helloprj
Define value for property 'version' 1.0-SNAPSHOT: : 
[INFO] Using property: package = com.liumiao
Confirm properties configuration:
groupId: com.liumiao
artifactId: helloprj
version: 1.0-SNAPSHOT
package: com.liumiao
 Y: : Y
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Archetype: maven-archetype-quickstart:1.4
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: groupId, Value: com.liumiao
[INFO] Parameter: artifactId, Value: helloprj
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: package, Value: com.liumiao
[INFO] Parameter: packageInPathFormat, Value: com/liumiao
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] Parameter: package, Value: com.liumiao
[INFO] Parameter: groupId, Value: com.liumiao
[INFO] Parameter: artifactId, Value: helloprj
[INFO] Project created from Archetype in dir: /Users/liumiao/json/json/maven/helloprj
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 29.686 s
[INFO] Finished at: 2020-06-07T19:43:35+08:00
[INFO] ------------------------------------------------------------------------
liumiaocn:maven liumiao$

目錄結構

自動生成的目錄結構包括一個單體測試文件、一個示例main文件，一個pom.xml文件，詳細如下所示

liumiaocn:maven liumiao$ tree .
.
└── helloprj
    ├── pom.xml
    └── src
        ├── main
        │   └── java
        │       └── com
        │           └── liumiao
        │               └── App.java
        └── test
            └── java
                └── com
                    └── liumiao
                        └── AppTest.java

10 directories, 3 files
liumiaocn:maven liumiao$

構建

liumiaocn:maven liumiao$ cd helloprj/
liumiaocn:helloprj liumiao$ mvn clean package
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------< com.liumiao:helloprj >------------------------
[INFO] Building helloprj 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:3.1.0:clean (default-clean) @ helloprj ---
[INFO] 
[INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ helloprj ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/liumiao/json/json/maven/helloprj/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:compile (default-compile) @ helloprj ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/liumiao/json/json/maven/helloprj/target/classes
[INFO] 
[INFO] --- maven-resources-plugin:3.0.2:testResources (default-testResources) @ helloprj ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /Users/liumiao/json/json/maven/helloprj/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.0:testCompile (default-testCompile) @ helloprj ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/liumiao/json/json/maven/helloprj/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:2.22.1:test (default-test) @ helloprj ---
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.liumiao.AppTest
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.026 s - in com.liumiao.AppTest
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] 
[INFO] 
[INFO] --- maven-jar-plugin:3.0.2:jar (default-jar) @ helloprj ---
[INFO] Building jar: /Users/liumiao/json/json/maven/helloprj/target/helloprj-1.0-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.084 s
[INFO] Finished at: 2020-06-07T19:47:25+08:00
[INFO] ------------------------------------------------------------------------
liumiaocn:helloprj liumiao$ 

執行

liumiaocn:helloprj liumiao$ java -jar target/helloprj-1.0-SNAPSHOT.jar
no main manifest attribute, in target/helloprj-1.0-SNAPSHOT.jar
liumiaocn:helloprj liumiao$ 

提示出現沒有main的設定，有多種對應方法，比如執行時指定：

liumiaocn:helloprj liumiao$ java -cp target/helloprj-1.0-SNAPSHOT.jar com.liumiao.App
Hello World!
liumiaocn:helloprj liumiao$

或者修改pom.xml配置文件，當前自動生成的pom文件內容如下所示：

liumiaocn:helloprj liumiao$ cat pom.xml 
<?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.liumiao</groupId>
  <artifactId>helloprj</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>helloprj</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>3.7.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-project-info-reports-plugin</artifactId>
          <version>3.0.0</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>
liumiaocn:helloprj liumiao$ 

將打jar包部分的設定做如下修改，打出的jar包中自然就會找到main函數了

        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>3.0.2</version>
          <configuration>
            <archive>
              <manifest>
                <mainClass>com.liumiao.App</mainClass>
              </manifest>
            </archive>
          </configuration>
        </plugin>

執行結果如下所示

liumiaocn:helloprj liumiao$ java -jar target/helloprj-1.0-SNAPSHOT.jar
Hello World!
liumiaocn:helloprj liumiao$