java - GraalVM - 在类路径上找不到语言和多语言实现

Question

我正在尝试在项目中使用 GraalVM 来添加简单的脚本功能。我使用 Maven 进行依赖项管理来加载 Graal 的基本依赖项。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!!!\");");
  }

}

虽然据我所知这应该有效，但运行它时，它会输出以下错误:

[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，正如错误所述，建议的解决方案是将 truffle-api.jar 包含在类路径中，但是由于它在插件环境中运行，因此让该插件的最终用户必须手动设置其类路径并不理想。 truffle-api Maven 依赖项中的阴影似乎不起作用，这通常是此类问题的解决方案。

已经提出了一些现有的解决方案。我第一次遇到的是this answer ，但正如您在我的 pom.xml 中看到的，所有这些依赖项都已包含在内。

我见过的其他解决方案(以及问题)在 this GitHub issue 中概述。 ，但是虽然我可以确认修改后的 META-INF/truffle/language 文件位于我的最终 jar 中，但它似乎不起作用。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，我现在有点不知道该怎么办。有人对如何解决这个问题有任何想法吗？

Answer 1

到目前为止，我发现解决此问题的最佳方法是将上下文类加载器交换为正确的类加载器，然后再将其交换回来:

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，这样您就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
});

显然这并不理想，因为它要求您每次调用 Graal 代码时都更改上下文。如果有人有更好的解决方案，我很乐意看到!