java - 使用反射调用具有通用参数的方法

Question

我试图将两个已知类型的泛型(accumulationFunction、resultBindings)传递到下面的反射调用例程中，但我遇到了麻烦。有人可以帮助我了解如何实现这一目标吗？

package com.amir.method.compiler;

//hidden imports

import java.util.Set;

public class CompiledReferencedAttributeMethod implements CompiledMethod {

    final Class<?> generatedClazz;
    //how do i pass the arguments below into the invoke routine??
    final KnownWorkData<AccumulationFunction> accumulationFunction;
    final KnownWorkData<Set<Executable<InstanceSetValue>>> resultBindings;

    public CompiledReferencedAttributeMethod(final int hash,
                                             final KnownWorkData<AccumulationFunction> accumulationFunction,
                                             final KnownWorkData<Set<Executable<InstanceSetValue>>> resultBindings) {
        this.generatedClazz = ReferencedAttributeMethodGenerator.get().compileMethod(
                "com.amir.hotspot.GeneratedGRAMethod" +hash, "dynamicGra", accumulationFunction, resultBindings);
        this.accumulationFunction = accumulationFunction;
        this.resultBindings = resultBindings;
    }

    @Override
    public WorkDataValue invokeCompiled(final Instance onInst,
                                        final ExecutionParms parm,
                                        final WorkDataDefinition returntype,
                                        final TaskContext context) {
        try {
            return (WorkDataValue) this.generatedClazz
                    .getMethod("dynamicGra",
                            Instance.class,
                            ExecutionParms.class,
                            WorkDataDefinition.class,
                            TaskContext.class)
                    .invoke(null, onInst, parm, returntype, this.accumulationFunction, this.resultBindings, context);
        } catch(Exception e) {
            throw new ExecuteCompiledMethodException(this.toString(), e);
        }
    }

}

Answer 1

由于您无法使用泛型和不同参数重载方法(请参阅: Oracle’s tutorial “Restrictions on Generics” )，因此您不必担心反射 API 的泛型。

没有歧义，你可以简单地得到你的方法:

Method m = this.generatedClazz.getMethod("dynamicGra",
                            Instance.class,
                            ExecutionParms.class,
                            WorkDataDefinition.class,
                            KnownWorkData.class,
                            KnownWorkData.class,
                            TaskContext.class);

然后您使用 null 进行调用，因此这意味着dynamicGra 必须是静态的，如果不是这种情况，您必须传递要调用该方法的 generatedClazz 实例:

Object instance = this.generatedClazz.newInstance(); // A new one or any other reference of generatedClazz
m.invoke(instance, onInst, parm, returntype, this.accumulationFunction, this.resultBindings, context);