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[英]Can I compile a Scala project with mixed java and scala code with dependencies both ways in Maven?
[英]My mixed Scala/Java Maven project doesn't compile
我有一個不能很好編譯的混合 Scala/Java 項目。
當 Java 代碼試圖調用同一個包中的 Scala 代碼時,就會出現問題。
當然,我有標准布局:
我看過其他類似的 Stackoverflow 問題,但這個問題有點過時了。 這另一個問題也無濟於事。
我還關注了scala-maven-plugin 文檔頁面。
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.1.6</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.0.2</version>
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<executions>
<execution>
<id>scala-compile-first</id>
<phase>process-resources</phase>
<goals>
<goal>add-source</goal>
<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>
<executions>
<execution>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
我曾嘗試關注此博客文章,但未成功。
從 pom.xml 導入的帶有 Scala 插件的 IDEA 項目可以成功編譯和運行我的項目。
正確的做法是什么? Java 代碼會被編譯兩次嗎? 首先是 Scala 插件和 Java 插件?。
這是 pom.xml 的一個工作示例:
<?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>stackoverflow</groupId>
<artifactId>q24448582</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<scala.version>2.10.3</scala.version>
</properties>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
<version>2.15.2</version>
<executions>
<execution>
<id>compile</id>
<goals>
<goal>compile</goal>
</goals>
<phase>compile</phase>
</execution>
<execution>
<id>test-compile</id>
<goals>
<goal>testCompile</goal>
</goals>
<phase>test-compile</phase>
</execution>
<execution>
<phase>process-resources</phase>
<goals>
<goal>compile</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
問題一
起初我認為問題是由於使用了現代版本的 maven-compiler-plugin。 我使用的是 3.0 版而不是 2.0.2 版。
解決方案是: - 刪除 maven-compiler-plugin - 添加此設置:增量
最后我的 pom.xml 是這樣的:
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.1.6</version>
<configuration>
<recompileMode>incremental</recompileMode>
<args>
<arg>-deprecation</arg>
<arg>-explaintypes</arg>
<arg>-target:jvm-1.7</arg>
</args>
</configuration>
<executions>
<execution>
<id>scala-compile-first</id>
<phase>process-resources</phase>
<goals>
<goal>add-source</goal>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>scala-test-compile</id>
<phase>process-test-resources</phase>
<goals>
<goal>add-source</goal>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
問題二
我遇到的另一個問題是:
<dependencies>
<dependency>
<groupId>org.json4s</groupId>
<artifactId>json4s-native_${scala.version}</artifactId>
<version>3.2.9</version>
</dependency>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala.version}.4</version>
</dependency>
</dependencies>
<properties>
<scala.version>2.10</scala.version>
</properties>
這使得這個解決的問題出現了: https : //issues.scala-lang.org/browse/SI-5733
可能它使用的是舊版本的 Scala 編譯器。
解決方案是將 scala.version 重命名為 scala.major,因為該屬性具有特殊含義。
為了讓 scala-maven-plugin 尊重 Java 1.8,但仍然允許 java 和 scala 的混合編譯,我們使用這個:
...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
<executions>
<execution>
<id>default-compile</id>
<phase>none</phase>
</execution>
</executions>
</plugin>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.2.2</version>
<configuration>
<recompileMode>incremental</recompileMode>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
...
我在pom.xml
文件<build>
塊中添加了打擊代碼並且運行良好!
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<!-- SCALA AND JAVA MIX COMPILATION -->
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<executions>
<execution>
<id>scala-compile</id>
<goals>
<goal>compile</goal>
</goals>
</execution>
<execution>
<id>scala-test-compile</id>
<goals>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.2</version>
<configuration>
<artifactSet>
<includes>
<include>*:*</include>
</includes>
</artifactSet>
<filters>
<filter>
<artifact>*:*</artifact>
<excludes>
<exclude>META-INF/*.SF</exclude>
<exclude>META-INF/*.DSA</exclude>
<exclude>META-INF/*.RSA</exclude>
</excludes>
</filter>
</filters>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<finalName>${project.artifactId}-shaded-${project.version}</finalName>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
<pluginManagement>
...
</pluginManagement>
<resources>
...
</resources>
</build>
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