Java&Scala混合编程

1. mvn 创建一个普通的java工程后，添加如下信息：

<?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>org.jerry</groupId>
<artifactId>mix-test</artifactId>
<version>1.0-SNAPSHOT</version>

<properties>
<jackson.version>2.4.2</jackson.version>
<scala.version>2.11.1</scala.version>
<slf4j.version>1.7.7</slf4j.version>
<scala.maven.version>2.11.1</scala.maven.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<build>
<defaultGoal>package</defaultGoal>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
<resource>
<directory>src/test/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<configuration>
<encoding>${project.build.sourceEncoding}</encoding>
</configuration>
<executions>
<execution>
<goals>
<goal>copy-resources</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.2.0</version>
<configuration>
<recompileMode>incremental</recompileMode>
<args>
<arg>-target:jvm-1.7</arg>
</args>
<javacArgs>
<javacArg>-source</javacArg>
<javacArg>1.7</javacArg>
<javacArg>-target</javacArg>
<javacArg>1.7</javacArg>
</javacArgs>
</configuration>
<executions>
<execution>
<id>scala-compile</id>
<phase>process-resources</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>scala-test-compile</id>
<phase>process-test-resources</phase>
<goals>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
<executions>
<execution>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
</executions>
</plugin>

</plugins>
<pluginManagement>
<plugins>
<!--This plugin's configuration is used to store Eclipse m2e settings
only. It has no influence on the Maven build itself. -->
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>
net.alchim31.maven
</groupId>
<artifactId>
scala-maven-plugin
</artifactId>
<versionRange>
[3.1.6,)
</versionRange>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
</pluginExecutionFilter>
<action>
<ignore></ignore>
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>

</project>

2. 在src/main/下，创建 scala 目录
                   src/main/java

                   src/main/scala

3. demo:

Java class:

//package mix.java.scala;

public class GreetingInJava {
public void greet() {
System.out.println("Hello World!");
}
}

Scala class:
class GreetingInScala {
def greet: Unit = {
val delegate: GreetingInJava = new GreetingInJava
delegate.greet
}
}

Java class:
public class Bootstrap {

public static void main(String[] args) {
GreetingInScala scala = new GreetingInScala();
scala.greet();
}
}