Java&Scala混合编程

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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();    }}

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