Scala從Java8升級到Java11踩過的坑

首先要考慮到JDK11和scala的兼容性，根據實際情況選擇需要的scala版本

JDK&Scala Compatibility

問題 01

Detect muti scala-library version

原因

同一個依賴有多個版本，maven不知道選擇哪個

解決方案

1. 同一依賴maven會根據路徑最短原則選擇依賴，依賴路徑相同會根據聲明優先選擇
   可以根據這個特性，使想要用的版本被選擇
2. Dependency_Management是一個更好的選擇，如果在dependency_Management中指定只能用某個版本，maven只會選擇這個版本
   DependencyManagement官方介紹

<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala-library.version}</version>
</dependency>
</dependencies>
</dependencyManagement>

問題02

error: object parsing is not a member of package util

原因

因爲 scala-parser-combinators 依賴在2.11中被移除了，必須自己添加

解決方案

<dependency>
<groupId>org.scala-lang.modules</groupId>
<artifactId>scala-parser-combinators_2.13</artifactId>
<version>1.1.2</version>
</dependency>

問題03

[ERROR] (class java.lang.RuntimeException/error reading Scala signature of JSON.class: Scala signature JSON has wrong version

原因

因爲 scala-parser-combinators 的版本太高了

解決方案

<dependency>
<groupId>org.scala-lang.modules</groupId>
<artifactId>scala-parser-combinators_2.12</artifactId>
<version>1.1.0</version>
</dependency>

問題04

FATAL ERROR in native method: processing of -javaagent failed
Exception in thread “main” java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
Caused by: java.lang.NoSuchFieldException: $jacocoAccess
at java.base/java.lang.Class.getField(Class.java:2000)

原因

因爲jacoco-maven-plugin插件只支持到JAVA9

解決方案

<plugin>
<groupId>org.jacoco</groupId>
<artifactId>jacoco-maven-plugin</artifactId>
<version>0.8.4</version>
</plugin>

問題05

Exception in thread “ScalaTest-main” java.lang.NoClassDefFoundError: org/scalacheck/Test$TestCallback at org.scalatest.tools.Runner$.runOptionallyWithPassFailReporter(Runner.scala:919)
at org.scalatest.tools.Runner$.main(Runner.scala:832) at org.scalatest.tools.Runner.main(Runner.scala) Caused by: java.lang.ClassNotFoundException: org.scalacheck.Test$TestCallback
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
… 3 more

原因

缺少scalacheck_2.13依賴

解決方案

<dependency>
<groupId>org.scalacheck</groupId>
<artifactId>scalacheck_2.13</artifactId>
<version>1.14.0</version>
<scope>test</scope>
</dependency>

問題06

error: object parsing is not a member of package util

原因

因爲 scala-parser-combinators 依賴在2.11中被移除了，如果需要必須自己添加

解決方案

<dependency>
<groupId>org.scala-lang.modules</groupId>
<artifactId>scala-parser-combinators_2.13</artifactId>
<version>1.1.2</version>
</dependency>

問題07

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-failsafe-plugin:2.20:integration-test (integration-test) on project commons-ui-expweb: Execution integration-test of goal o
rg.apache.maven.plugins:maven-failsafe-plugin:2.20:integration-test failed: A required class was missing while executing org.apache.maven.plugins:maven-failsafe-plugin:2.20:integration-
test: javax/xml/bind/JAXBException

原因

maven-failsafe-plugin版本太低，與scala不能很好兼容

解決方案

<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-failsafe-plugin</artifactId>
<version>3.0.0-M3</version>
<executions>
<execution>
<id>integration-test</id>
<goals>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
</execution>
</executions>
</plugin>

Tips:查看依賴
mvn dependency:tree