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Ant example source code file (DispatchUtils.java)

This example Ant source code file (DispatchUtils.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 - Ant tags/keywords

buildexception, buildexception, class, dispatchable, dispatchable, method, no, nosuchmethodexception, object, object, reflection, string, task, unknownelement, unknownelement

The DispatchUtils.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.tools.ant.dispatch;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.UnknownElement;
import org.apache.tools.ant.Task;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * Determines and Executes the action method for the task.
 */
public class DispatchUtils {
    /**
     * Determines and Executes the action method for the task.
     * @param task the task to execute.
     * @throws BuildException on error.
     */
    public static final void execute(Object task) throws BuildException {
        String methodName = "execute";
        Dispatchable dispatchable = null;
        try {
            if (task instanceof Dispatchable) {
                dispatchable = (Dispatchable) task;
            } else if (task instanceof UnknownElement) {
                UnknownElement ue = (UnknownElement) task;
                Object realThing = ue.getRealThing();
                if (realThing != null
                    && realThing instanceof Dispatchable
                    && realThing instanceof Task) {
                    dispatchable = (Dispatchable) realThing;
                }
            }
            if (dispatchable != null) {
                String mName = null;
                try {
                    final String name = dispatchable.getActionParameterName();
                    if (name != null && name.trim().length() > 0) {
                        mName = "get" + name.trim().substring(0, 1).toUpperCase();
                        if (name.length() > 1) {
                            mName += name.substring(1);
                        }
                        final Class c = dispatchable.getClass();
                        final Method actionM = c.getMethod(mName, new Class[0]);
                        if (actionM != null) {
                            final Object o = actionM.invoke(dispatchable, (Object[]) null);
                            if (o != null) {
                                final String s = o.toString();
                                if (s != null && s.trim().length() > 0) {
                                    methodName = s.trim();
                                    Method executeM = null;
                                    executeM = dispatchable.getClass().getMethod(
                                        methodName, new Class[0]);
                                    if (executeM == null) {
                                        throw new BuildException(
                                            "No public " + methodName + "() in "
                                            + dispatchable.getClass());
                                    }
                                    executeM.invoke(dispatchable, (Object[]) null);
                                    if (task instanceof UnknownElement) {
                                        ((UnknownElement) task).setRealThing(null);
                                    }
                                } else {
                                    throw new BuildException(
                                        "Dispatchable Task attribute '" + name.trim()
                                        + "' not set or value is empty.");
                                }
                            } else {
                                    throw new BuildException(
                                        "Dispatchable Task attribute '" + name.trim()
                                        + "' not set or value is empty.");
                            }
                        }
                    } else {
                        throw new BuildException(
                            "Action Parameter Name must not be empty for Dispatchable Task.");
                    }
                } catch (NoSuchMethodException nsme) {
                    throw new BuildException("No public " + mName + "() in " + task.getClass());
                }
            } else {
                Method executeM = null;
                executeM = task.getClass().getMethod(methodName, new Class[0]);
                if (executeM == null) {
                    throw new BuildException("No public " + methodName + "() in "
                        + task.getClass());
                }
                executeM.invoke(task, (Object[]) null);
                if (task instanceof UnknownElement) {
                    ((UnknownElement) task).setRealThing(null);
                }
            }
        } catch (InvocationTargetException ie) {
            Throwable t = ie.getTargetException();
            if (t instanceof BuildException) {
                throw ((BuildException) t);
            } else {
                throw new BuildException(t);
            }
        } catch (NoSuchMethodException e) {
            throw new BuildException(e);
        } catch (IllegalAccessException e) {
            throw new BuildException(e);
        }
    }
}

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