如何在 Java 应用程序中在 Android 上运行 Lua 脚本? [英] How do I run Lua scripts on Android in a Java application?

问题描述

我正在用 Java 开发一款使用 Lua 脚本的 Android 游戏.为了执行这些脚本，我将 LuaJ 与 Java 的 ScriptEngine 类一起使用.例如...

I'm developing an Android game in Java which uses Lua scripts. To execute these scripts, I'm using LuaJ with Java's ScriptEngine class. For example...

ScriptEngineManager sem = new ScriptEngineManager();
scriptEngine = sem.getEngineByExtension(".lua");
script = ((Compilable)scriptEngine).compile("some lua here");

然而，这显然在 Android 上不受支持(与 android 没有完整的 JVM 有关系，我在某处读到过).有没有办法在 Android 上使用 Lua 脚本?也许有 LuaJ 替代品?也许有一种直接使用 LuaJ 编译和执行 Lua 脚本的方法(虽然我看不到如何).

However, this is apparently not supported on Android (something to do with android not having a full blown JVM, I read somewhere). Is there a way I can use Lua scripts on Android? Maybe there's a LuaJ alternative? Perhaps there is a way of compiling and executing Lua scripts using LuaJ directly (though I can't see how).

仅供参考，当我尝试在 Android 上运行此代码时看到此错误:

FYI, I see this error when I try to run this code on Android:

05-06 16:12:32.870: E/dalvikvm(17509): Could not find class 'javax.script.ScriptEngineManager', referenced from method unearth.levels.LevelReader.<init>
05-06 16:12:32.870: W/dalvikvm(17509): VFY: unable to resolve new-instance 787 (Ljavax/script/ScriptEngineManager;) in Lunearth/levels/LevelReader;
05-06 16:12:32.870: D/dalvikvm(17509): VFY: replacing opcode 0x22 at 0x0018
05-06 16:12:32.875: E/dalvikvm(17509): Could not find class 'javax.script.Compilable', referenced from method unearth.levels.LevelReader.parseScript
05-06 16:12:32.875: W/dalvikvm(17509): VFY: unable to resolve check-cast 782 (Ljavax/script/Compilable;) in Lunearth/levels/LevelReader;
05-06 16:12:32.875: D/dalvikvm(17509): VFY: replacing opcode 0x1f at 0x0047
05-06 16:12:32.875: W/dalvikvm(17509): VFY: unable to resolve exception class 788 (Ljavax/script/ScriptException;)
05-06 16:12:32.875: W/dalvikvm(17509): VFY: unable to find exception handler at addr 0x51
05-06 16:12:32.875: W/dalvikvm(17509): VFY:  rejected Lunearth/levels/LevelReader;.parseScript (Lorg/w3c/dom/Element;Lunearth/levels/Level;)V
05-06 16:12:32.875: W/dalvikvm(17509): VFY:  rejecting opcode 0x0d at 0x0051
05-06 16:12:32.875: W/dalvikvm(17509): VFY:  rejected Lunearth/levels/LevelReader;.parseScript (Lorg/w3c/dom/Element;Lunearth/levels/Level;)V
05-06 16:12:32.875: W/dalvikvm(17509): Verifier rejected class Lunearth/levels/LevelReader;
05-06 16:12:32.890: W/dalvikvm(17509): threadid=11: thread exiting with uncaught exception (group=0x40c331f8)
05-06 16:12:32.895: E/AndroidRuntime(17509): FATAL EXCEPTION: GLThread 1062
05-06 16:12:32.895: E/AndroidRuntime(17509): java.lang.VerifyError: unearth/levels/LevelReader
05-06 16:12:32.895: E/AndroidRuntime(17509):    at unearth.Game.startGame(Game.java:201)
05-06 16:12:32.895: E/AndroidRuntime(17509):    at unearth.Game.update(Game.java:713)
05-06 16:12:32.895: E/AndroidRuntime(17509):    at unearth.screens.LoadScreen.update(LoadScreen.java:56)
05-06 16:12:32.895: E/AndroidRuntime(17509):    at unearth.UnearthListener.render(UnearthListener.java:71)
05-06 16:12:32.895: E/AndroidRuntime(17509):    at com.badlogic.gdx.backends.android.AndroidGraphics.onDrawFrame(AndroidGraphics.java:423)
05-06 16:12:32.895: E/AndroidRuntime(17509):    at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1462)
05-06 16:12:32.895: E/AndroidRuntime(17509):    at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1216)
05-06 16:12:58.600: D/dalvikvm(17509): GC_CONCURRENT freed 334K, 3% free 16196K/16647K, paused 2ms+6ms

更新:

也许这个项目有一些有用的代码?http://code.google.com/p/android-scripting/>

推荐答案

我找到了在 Android 上使用 LuaJ 的方法！:-)

I found a way of using LuaJ on Android! :-)

关键是直接使用 LuaJ API，而不是通过 javax.script.由于没有教程，弄清楚这有点棘手，所以这里有一个之前和之后，以便其他人不必通过挑选 LuaJ 源代码和 JavaDoc.我真的希望这对某人有所帮助，因为它让我发疯了！

The key is to use the LuaJ API directly as opposed to through javax.script. It's a little tricky to figure out as there's no tutorials, so here's a before and after so that others don't have to go through picking through the LuaJ source code and JavaDoc. I really hope this helps someone as it drove me bonkers!

注意:secretgame"不是我游戏的实际名称;-)

Note: "secretgame" isn't the actual name of my game ;-)

之后:

package secretgame.scripting;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

import org.luaj.vm2.LuaClosure;
import org.luaj.vm2.LuaTable;
import org.luaj.vm2.LuaValue;
import org.luaj.vm2.Prototype;
import org.luaj.vm2.compiler.LuaC;
import org.luaj.vm2.lib.jse.CoerceJavaToLua;
import org.luaj.vm2.lib.jse.JsePlatform;

import secretgame.SecretGameException;
import secretgame.events.EventArgs;
import secretgame.levels.Level;

public class DirectLuaj implements Lua
{
  private final Level level;
  private final ScriptTools scriptTools;
  private final ScriptEvents scriptEvents;
  private int nextId = 0;
  private ArrayList<LuaClosure> scripts = new ArrayList<LuaClosure>();

  public DirectLuaj(Level level, ScriptTools scriptTools,
      ScriptEvents scriptEvents)
  {
    this.level = level;
    this.scriptTools = scriptTools;
    this.scriptEvents = scriptEvents;
  }

  @Override
  public int add(String scriptText) throws SecretGameException
  {
    try {
      InputStream input = new ByteArrayInputStream(scriptText.getBytes());
      Prototype p = LuaC.compile(input, "script");
      LuaValue g = JsePlatform.standardGlobals();
      LuaClosure c = new LuaClosure(p, g);
      scripts.add(c);
    }
    catch (IOException e) {
      throw new SecretGameException("compile failed", e);
    }

    return nextId++;
  }

  @Override
  public void run(int id, EventArgs args) throws SecretGameException
  {
    LuaClosure script = scripts.get(id);

    LuaTable bindings = new LuaTable();

    bindings.set("java", toLua(scriptTools));
    bindings.set("level", toLua(level));
    bindings.set("args", toLua(args));
    bindings.set("events", toLua(scriptEvents));

    script.setfenv(bindings);

    script.call();
  }

  private LuaValue toLua(Object javaValue) {
    return javaValue == null? LuaValue.NIL:
            javaValue instanceof LuaValue? (LuaValue) javaValue:
            CoerceJavaToLua.coerce(javaValue);
  }
}

之前:

package secretgame.scripting;

import java.util.ArrayList;

import javax.script.Bindings;
import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

import secretgame.SecretGameException;
import secretgame.events.EventArgs;
import secretgame.levels.Level;

// sadly this won't work on Android because there's no such thing
// as javax.script in Dalvik ... dumb Android java :|
public class JavaxScriptingLua implements Lua
{
  private ScriptEngine scriptEngine;
  private final Level level;
  private final ScriptTools scriptTools;
  private final ScriptEvents scriptEvents;
  private int nextId = 0;
  private ArrayList<CompiledScript> scripts = new ArrayList<CompiledScript>();

  public JavaxScriptingLua(Level level, ScriptTools scriptTools, ScriptEvents scriptEvents)
  {
    this.level = level;
    this.scriptTools = scriptTools;
    this.scriptEvents = scriptEvents;

    ScriptEngineManager sem = new ScriptEngineManager();
    scriptEngine = sem.getEngineByExtension(".lua");
  }

  public int add(String scriptText) throws SecretGameException
  {
    try {
      CompiledScript script = ((Compilable)scriptEngine).compile(scriptText);
      scripts.add(script);
    }
    catch (ScriptException e) {
      throw new SecretGameException("could not compile lua.", e);
    }

    return nextId++;
  }

  public void run(int id, EventArgs args) throws SecretGameException
  {    
    Bindings bindings = scriptEngine.createBindings();

    bindings.put("java", scriptTools);
    bindings.put("level", level);
    bindings.put("args", args);
    bindings.put("events", scriptEvents);

    try {
      scripts.get(id).eval(bindings);
    }
    catch (ScriptException e) {
      throw new SecretGameException("could not run script.", e);
    }
  }
}

这篇关于如何在 Java 应用程序中在 Android 上运行 Lua 脚本?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！