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Groovy example source code file (MethodCaller.java)

This example Groovy source code file (MethodCaller.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Groovy tags/keywords

class, class, classgeneratorexception, could, method, method, methodcaller, methodcaller, opcodes, reflection, string, string

The Groovy MethodCaller.java source code

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.classgen.asm;

import java.lang.reflect.Method;

import org.codehaus.groovy.classgen.ClassGeneratorException;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

/**
 * A helper class to invoke methods more easily in ASM
 * 
 * @author <a href="mailto:james@coredevelopers.net">James Strachan
 * @version $Revision: 20965 $
 */
public class MethodCaller implements Opcodes {

    private int opcode;
    private String internalName;
    private String name;
    private Class theClass;
    private String methodDescriptor;

    public static MethodCaller newStatic(Class theClass, String name) {
        return new MethodCaller(INVOKESTATIC, theClass, name);
    }

    public static MethodCaller newInterface(Class theClass, String name) {
        return new MethodCaller(INVOKEINTERFACE, theClass, name);
    }

    public static MethodCaller newVirtual(Class theClass, String name) {
        return new MethodCaller(INVOKEVIRTUAL, theClass, name);
    }

    public MethodCaller(int opcode, Class theClass, String name) {
        this.opcode = opcode;
        this.internalName = Type.getInternalName(theClass);
        this.theClass = theClass;
        this.name = name;

    }

    public void call(MethodVisitor methodVisitor) {
        methodVisitor.visitMethodInsn(opcode, internalName, name, getMethodDescriptor());
    }

    public String getMethodDescriptor() {
        if (methodDescriptor == null) {
            Method method = getMethod();
            methodDescriptor = Type.getMethodDescriptor(method);
        }
        return methodDescriptor;
    }

    protected Method getMethod() {
        Method[] methods = theClass.getMethods();
        for (int i = 0; i < methods.length; i++) {
            Method method = methods[i];
            if (method.getName().equals(name)) {
                return method;
            }
        }
        throw new ClassGeneratorException("Could not find method: " + name + " on class: " + theClass);
    }
}

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