KING

maven

• make sure ‘mvn -v’ return the current version in you computer
• otherwise, install the maven first

Hello world

• project hierarchy
  • helloworld (folder)
    • (root directory)
    • src
      • main
        • java
          • hello
            • Greeter.java
            • HelloWorld.java
    • target(auto generate after mvn install)
      • helloworld-0.1.0.jar
    • pom.xml

class

• mkdir -p src/main/java/hello
  • make a directory to put the java class
• create two class HelloWorld.java and Greeter.java

  • HelloWorld.java

    • “` package hello;

      import org.joda.time.LocalTime;

      public class HelloWorld{ public static void main(String[] args){ LocalTime currentTime = new LocalTime(); System.out.println(“The currentTime local time is ” + currentTime); Greeter greeter = new Greeter(); System.out.println(greeter.sayHello()); } }

    “`

  • Greeter.java

    • “` package hello;

      public class Greeter { public String sayHello() { return “Hello world!”; } } “`

configuration

• pom.xml
  • put the file in the root of the project

  • “` <?xml version=“1.0” encoding=“UTF-8”?> 4.0.0 org.springframework helloworld jar 0.1.0

      <!--- 插件 -->
      <dependencies>
          <dependency>
              <groupId>joda-time</groupId>
              <artifactId>joda-time</artifactId>
              <version>2.2</version>
          </dependency>
      </dependencies>
    
      <build>
          <plugins>
              <plugin>
                  <groupId>org.apache.maven.plugins</groupId>
                  <artifactId>maven-shade-plugin</artifactId>
                  <version>2.1</version>
                  <executions>
                      <execution>
                          <phase>package</phase>
                          <goals>
                              <goal>shade</goal>
                          </goals>
                          <configuration>
                              <transformers>
                                  <transformer
                                      implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                      <mainClass>hello.HelloWorld</mainClass>
                                  </transformer>
                              </transformers>
                          </configuration>
                      </execution>
                  </executions>
              </plugin>
          </plugins>
      </build>
    

    “`

run the maven project

• compile
  • mvn compile
• install
  • mvn install
• two ways to run
  • java -jar helloworld-0.1.0.jar
  • mvn exec:java -Dexec.mainClass=“hello.HelloWorld”