[英]How to assemble an SBT Scala library to be included in a Java 7 Maven project?
我在通過sbt-assembly構建Scala庫時遇到麻煩,因此無法將其合並到Java Maven項目中。 但是,我已經成功地將Scala庫導入另一個Scala SBT項目,因此,從Scala / SBT的角度來看,它至少似乎是有效的JVM二進制文件。
打包Scala庫時,我使用命令sbt assembly
,然后通過以下方式在本地發布它:
╰─$ mvn install:install-file \
-Dfile=/full/path/to/develop/hello/test-library/target/scala-2.11/test-library-assembly-0.1.0-SNAPSHOT.jar \
-DgroupId="com.example" \
-DartifactId="test-library" \
-Dversion="0.1.0-SNAPSHOT" \
-DgeneratePom=true \
-Dpackaging=jar
我嘗試從Java使用庫時看到的錯誤消息如下:
(通過mvn是3.3.9版本的 mvn clean package
包裝之后)
╰─$ java -jar target/my-app-1.0-SNAPSHOT.jar
Exception in thread "main" java.lang.NoClassDefFoundError: example/hello/Hello
at com.mycompany.app.App.main(App.java:19)
Caused by: java.lang.ClassNotFoundException: example.hello.Hello
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 1 more
我的Scala項目如下所示:
build.sbt
import Dependencies._
lazy val root = (project in file(".")).
settings(
inThisBuild(List(
organization := "com.example",
scalaVersion := "2.11.11",
version := "0.1.0-SNAPSHOT",
scalacOptions += "-target:jvm-1.7"
)),
name := "test-library",
libraryDependencies += scalaTest % Test
)
項目/ assembly.sbt
addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.5")
項目/ build.properties
sbt.version=0.13.16
的src /主/階/示例/你好/ Hello.scala
package example.hello
object Hello {
def main(args: Array[String]): Unit = {
println("Hello!!!")
}
}
Java項目如下
的pom.xml
<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany.app</groupId>
<artifactId>my-app</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>my-app</name>
<url>http://maven.apache.org</url>
<properties>
<maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
<encoding>UTF-8</encoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>com.mycompany.app.App</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.0.2</version>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.example</groupId>
<artifactId>test-library</artifactId>
<version>0.1.0-SNAPSHOT</version>
</dependency>
</dependencies>
</project>
的src / main / JAVA / COM / myCompany中/應用/ App.java
package com.mycompany.app;
import example.hello.*;
/**
* Hello world!
*
*/
public class App //extends URLClassLoader
{
public static void main( String[] args ) {
Hello.main(null);
}
}
該庫是否在test-library_2.11
下安裝?
不,不是的。 這是mvn install:install-file
命令的相關輸出。
[INFO] Installing /full/path/to/develop/hello/test-library/target/scala-2.11/test-library-assembly-0.1.0-SNAPSHOT.jar to /home/<my-name>/.m2/repository/com/example/test-library/0.1.0-SNAPSHOT/test-library-0.1.0-SNAPSHOT.jar
[INFO] Installing /tmp/mvninstall9208544268925838468.pom to /home/<my-name>/.m2/repository/com/example/test-library/0.1.0-SNAPSHOT/test-library-0.1.0-SNAPSHOT.pom
問題在於test-library
是uberjar,而my-app-1.0-SNAPSHOT.jar
不是。 將后者構建為uberjar之后,問題也得到解決。
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