GraalVM-在类路径上未找到语言和多语言实现

时间：2019-06-22 02:36:19

标签： java maven bukkit graalvm

我正在尝试在项目中使用GraalVM添加简单的脚本功能。我正在使用Maven进行依赖管理，以加载Graal的基本依赖。这是我的pom.xml：

<?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>cx.matthew</groupId>
  <artifactId>graaltest</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <graalvm.version>19.0.2</graalvm.version>
    <compiler.dir>${project.build.directory}/compiler</compiler.dir>
    <maven.compiler.source>1.6</maven.compiler.source>
    <maven.compiler.target>1.6</maven.compiler.target>
  </properties>

  <repositories>
    <repository>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <id>central</id>
      <name>Maven Repository Switchboard</name>
      <url>http://repo1.maven.org/maven2</url>
    </repository>
    <repository>
      <id>papermc</id>
      <url>https://papermc.io/repo/repository/maven-public/</url>
    </repository>
  </repositories>

  <dependencies>
    <dependency>
      <groupId>org.graalvm.sdk</groupId>
      <artifactId>graal-sdk</artifactId>
      <version>${graalvm.version}</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.graalvm.js</groupId>
      <artifactId>js</artifactId>
      <version>${graalvm.version}</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.graalvm.js</groupId>
      <artifactId>js-scriptengine</artifactId>
      <version>${graalvm.version}</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.graalvm.tools</groupId>
      <artifactId>profiler</artifactId>
      <version>${graalvm.version}</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.graalvm.tools</groupId>
      <artifactId>chromeinspector</artifactId>
      <version>${graalvm.version}</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.graalvm.truffle</groupId>
      <artifactId>truffle-api</artifactId>
      <version>19.0.0</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>com.destroystokyo.paper</groupId>
      <artifactId>paper-api</artifactId>
      <version>1.14.2-R0.1-SNAPSHOT</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
        <filtering>true</filtering>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>3.2.1</version>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

</project>

这是我调用Graal的代码：

package cx.matthew.graaltest;

import org.bukkit.plugin.java.JavaPlugin;
import org.graalvm.polyglot.Context;

public class GraalTestPlugin extends JavaPlugin {

  @Override
  public void onEnable() {
    Context context = Context.create();
    context.eval("js", "console.log(\"hi!!!\");");
  }

}

尽管据我所知，它应该可以运行，但运行时会输出以下错误：

[19:25:16 ERROR]: Error occurred while enabling GraalTest v1.0-SNAPSHOT (Is it up to date?)
java.lang.IllegalStateException: No language and polyglot implementation was found on the classpath. Make sure the truffle-api.jar is on the classpath.
    at org.graalvm.polyglot.Engine$PolyglotInvalid.noPolyglotImplementationFound(Engine.java:800) ~[?:?]
    at org.graalvm.polyglot.Engine$PolyglotInvalid.buildEngine(Engine.java:732) ~[?:?]
    at org.graalvm.polyglot.Engine$Builder.build(Engine.java:505) ~[?:?]
    at org.graalvm.polyglot.Context$Builder.build(Context.java:1304) ~[?:?]
    at org.graalvm.polyglot.Context.create(Context.java:697) ~[?:?]
    at cx.matthew.graaltest.GraalTestPlugin.onEnable(GraalTestPlugin.java:10) ~[?:?]
    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:263) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:338) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:419) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.craftbukkit.v1_14_R1.CraftServer.enablePlugin(CraftServer.java:464) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.craftbukkit.v1_14_R1.CraftServer.enablePlugins(CraftServer.java:378) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.craftbukkit.v1_14_R1.CraftServer.reload(CraftServer.java:854) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.Bukkit.reload(Bukkit.java:610) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:54) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.craftbukkit.v1_14_R1.CraftServer.dispatchCommand(CraftServer.java:736) ~[patched_1.14.2.jar:git-Paper-97]
    at org.bukkit.craftbukkit.v1_14_R1.CraftServer.dispatchServerCommand(CraftServer.java:698) ~[patched_1.14.2.jar:git-Paper-97]
    at net.minecraft.server.v1_14_R1.DedicatedServer.handleCommandQueue(DedicatedServer.java:457) ~[patched_1.14.2.jar:git-Paper-97]
    at net.minecraft.server.v1_14_R1.DedicatedServer.b(DedicatedServer.java:419) ~[patched_1.14.2.jar:git-Paper-97]
    at net.minecraft.server.v1_14_R1.MinecraftServer.a(MinecraftServer.java:1061) ~[patched_1.14.2.jar:git-Paper-97]
    at net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:905) ~[patched_1.14.2.jar:git-Paper-97]
    at java.lang.Thread.run(Thread.java:834) [?:?]

现在，当然，针对此错误的建议解决方案是在类路径中包含truffle-api.jar，但是由于此操作在插件环境中运行，让此插件的最终用户不理想必须手动设置其类路径。 truffle-api Maven依赖项中的阴影似乎不起作用，这通常是解决此类问题的方法。

已经提出了一些现有的解决方案。我遇到的第一个是在this answer中，但是正如您在pom.xml中所看到的那样，所有这些依赖项都已包括在内。

我见过的另一种解决方案（以及问题）在this GitHub issue中进行了概述，但是尽管我可以确认修改后的META-INF / truffle / language文件在我的最终jar中，但它并没有似乎在工作。这是jar中输出的文件：

language1.characterMimeType.0=application/tregex
language1.className=com.oracle.truffle.regex.RegexLanguage
language1.id=regex
language1.implementationName=
language1.interactive=false
language1.internal=true
language1.name=REGEX
language1.version=0.1

language2.characterMimeType.0=application/javascript
language2.characterMimeType.1=application/javascript+module
language2.characterMimeType.2=text/javascript
language2.className=com.oracle.truffle.js.lang.JavaScriptLanguage
language2.defaultMimeType=application/javascript
language2.dependentLanguage.0=regex
language2.fileTypeDetector0=com.oracle.truffle.js.lang.JSFileTypeDetector
language2.id=js
language2.implementationName=GraalVM JavaScript
language2.interactive=true
language2.internal=false
language2.name=JavaScript
language2.version=inherit

所以，我有点不知所措。是否有人对如何解决此问题有任何想法？

1 个答案:

答案 0 :(得分：0)

到目前为止，我发现解决此问题的最佳方法是将上下文ClassLoader换出正确的内容，然后再将其换回：

ClassLoader oldCl = Thread.currentThread().getContextClassLoader();
Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
// Insert Graal code here
Thread.currentThread().setContextClassLoader(oldCl);

您甚至可以将其设置为回调，因此您不必一遍又一遍地使用相同的代码：

private void runInPluginContext(ContextCallback callback) {
  ClassLoader oldCl = Thread.currentThread().getContextClassLoader();
  Thread.currentThread().setContextClassLoader(getClass().getClassLoader());
  callback.call();
  Thread.currentThread().setContextClassLoader(oldCl);
}

interface ContextCallback {

  void call();

}

并使用以下命令运行它：

runInPluginContext(() -> {
  // Insert Graal code here
});

这显然不是理想的，因为它要求您每次调用Graal代码时都要更改上下文。如果有人有更好的解决方案，我很乐意看到它！

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