java 8 - 通过绑定传递函数

Question

在 JS 中调用 java 函数时，无法在不同的范围内工作 (global/engine)。

engine.eval("function proxy(a){return Java.type('Foo').bar(a);}",engine.getBindings(ScriptContext.GLOBAL_SCOPE));
engine.eval("function withoutProxy(){return Java.type('Foo').bar(m);}",engine.getBindings(ScriptContext.ENGINE_SCOPE));
engine.eval("function withProxy(){return proxy(m);}", engine.getBindings(ScriptContext.ENGINE_SCOPE));

(其中m是在引擎范围内声明的JS函数)

调用 withoutProxy 工作正常。但是 withProxy 抛出

java.lang.ClassCastException: Cannot cast jdk.nashorn.api.scripting.ScriptObjectMirror to java.util.function.Function
at java.lang.invoke.MethodHandleImpl.newClassCastException(MethodHandleImpl.java:361)
at java.lang.invoke.MethodHandleImpl.castReference(MethodHandleImpl.java:356)
at jdk.nashorn.internal.scripts.Script$RecompilationA$\^eval\_.proxy(<eval>:1)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:639)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:494)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:393)
at jdk.nashorn.api.scripting.ScriptObjectMirror.call(ScriptObjectMirror.java:117)
at jdk.nashorn.internal.scripts.Script$Recompilation$\^eval\_.withProxy(<eval>:1)
at jdk.nashorn.internal.runtime.ScriptFunctionData.invoke(ScriptFunctionData.java:637)
at jdk.nashorn.internal.runtime.ScriptFunction.invoke(ScriptFunction.java:494)
at jdk.nashorn.internal.runtime.ScriptRuntime.apply(ScriptRuntime.java:393)
at jdk.nashorn.api.scripting.ScriptObjectMirror.callMember(ScriptObjectMirror.java:199)
at jdk.nashorn.api.scripting.NashornScriptEngine.invokeImpl(NashornScriptEngine.java:383)
at jdk.nashorn.api.scripting.NashornScriptEngine.invokeFunction(NashornScriptEngine.java:190)

（堆栈跟踪是使用 1.8.0_102-ea。与 jdk1.8.0_05 和 jdk1.8.0_73 相同的异常。）

所以：我是不是做错了什么，是故意的还是错误？

(Gist of my test class)

Answer 1

此问题现已通过 http://bugs.java.com/view_bug.do?bug_id=8162839 in JDK 9-ea b 147 which can be downloaded from https://jdk9.java.net/download/

解决

java 8 - 通过绑定传递函数

java 8 - Passing a function through bindings

java

java-8

nashorn