BryanSer / JDK8-Nashorn-BUG

A bug in Nashorn

JDK Version: 1.8.0_131

BUG Description:

When construct ScriptEngineManager to get Nashorn engine and the ClassLoader which you send to constructor isn't use to construct NashornScriptEngine.

中文版本: 此处

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Cause:

At jdk.nashorn.api.scripting.NashornScriptEngineFactory:431 static method getAppClassLoader()

byte code:

             * 0: invokestatic  java/lang/Thread.currentThread:()Ljava/lang/Thread;
             * 3: invokevirtual java/lang/Thread.getContextClassLoader:()Ljava/lang/ClassLoader;
             * 6: astore_0
             * 7: aload_0
             * 8: ifnonnull     19
             * 11: ldc           jdk/nashorn/api/scripting/NashornScriptEngineFactory
             * 13: invokevirtual java/lang/Class.getClassLoader:()Ljava/lang/ClassLoader;
             * 16: goto          20
             * 19: aload_0
             * 20: areturn  

Obviously the ClassLoader that returned is current thread's ClassLoader.

If what it returned is null then return NashornScriptEngineFactory's ClassLoader.

This means to construct ScriptEngineManager(ClassLoader loader) with a ClassLoader is useless.

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Repair:

Because getAppClassLoader returned classloader is current thread's ClassLoader.

Before ScriptEngineManager get Nashorn, edit the current thread's ClassLoader to achive the NashornScriptEngine use the classloader which you gave.

Repair class