Ant example source code file (Input.java)

This example Ant source code file (Input.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, handler, handler, handlers, handlertype, input, inputhandler, inputhandler, inputrequest, string, string, util, values, vector

The Input.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.taskdefs;

import java.util.Vector;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.input.DefaultInputHandler;
import org.apache.tools.ant.input.GreedyInputHandler;
import org.apache.tools.ant.input.InputHandler;
import org.apache.tools.ant.input.InputRequest;
import org.apache.tools.ant.input.MultipleChoiceInputRequest;
import org.apache.tools.ant.input.PropertyFileInputHandler;
import org.apache.tools.ant.types.EnumeratedAttribute;
import org.apache.tools.ant.util.ClasspathUtils;
import org.apache.tools.ant.util.StringUtils;

/**
 * Reads an input line from the console.
 *
 * @since Ant 1.5
 *
 * @ant.task category="control"
 */
public class Input extends Task {

    /**
     * Represents an InputHandler.
     */
    public class Handler extends DefBase {

        private String refid = null;
        private HandlerType type = null;
        private String classname = null;

        /**
         * Specify that the handler is a reference on the project;
         * this allows the use of a custom inputhandler.
         * @param refid the String refid.
         */
        public void setRefid(String refid) {
            this.refid = refid;
        }
        /**
         * Get the refid of this Handler.
         * @return String refid.
         */
        public String getRefid() {
            return refid;
        }
        /**
         * Set the InputHandler classname.
         * @param classname the String classname.
         */
        public void setClassname(String classname) {
            this.classname = classname;
        }
        /**
         * Get the classname of the InputHandler.
         * @return String classname.
         */
        public String getClassname() {
            return classname;
        }
        /**
         * Set the handler type.
         * @param type a HandlerType.
         */
        public void setType(HandlerType type) {
            this.type = type;
        }
        /**
         * Get the handler type.
         * @return a HandlerType object.
         */
        public HandlerType getType() {
            return type;
        }
        private InputHandler getInputHandler() {
            if (type != null) {
               return type.getInputHandler();
            }
            if (refid != null) {
               try {
                   return (InputHandler) (getProject().getReference(refid));
               } catch (ClassCastException e) {
                   throw new BuildException(
                       refid + " does not denote an InputHandler", e);
               }
            }
            if (classname != null) {
               return (InputHandler) (ClasspathUtils.newInstance(classname,
                   createLoader(), InputHandler.class));
            }
            throw new BuildException(
                "Must specify refid, classname or type");
        }
    }

    /**
     * EnumeratedAttribute representing the built-in input handler types:
     * "default", "propertyfile", "greedy".
     */
    public static class HandlerType extends EnumeratedAttribute {
        private static final String[] VALUES
            = {"default", "propertyfile", "greedy"};

        private static final InputHandler[] HANDLERS
            = {new DefaultInputHandler(),
               new PropertyFileInputHandler(),
               new GreedyInputHandler()};

        /** {@inheritDoc} */
        public String[] getValues() {
            return VALUES;
        }
        private InputHandler getInputHandler() {
            return HANDLERS[getIndex()];
        }
    }

    private String validargs = null;
    private String message = "";
    private String addproperty = null;
    private String defaultvalue = null;
    private Handler handler = null;
    private boolean messageAttribute;

    /**
     * Defines valid input parameters as comma separated strings. If set, input
     * task will reject any input not defined as accepted and requires the user
     * to reenter it. Validargs are case sensitive. If you want 'a' and 'A' to
     * be accepted you need to define both values as accepted arguments.
     *
     * @param validargs A comma separated String defining valid input args.
     */
    public void setValidargs (String validargs) {
        this.validargs = validargs;
    }

    /**
     * Defines the name of a property to be created from input. Behaviour is
     * according to property task which means that existing properties
     * cannot be overridden.
     *
     * @param addproperty Name for the property to be created from input
     */
    public void setAddproperty (String addproperty) {
        this.addproperty = addproperty;
    }

    /**
     * Sets the Message which gets displayed to the user during the build run.
     * @param message The message to be displayed.
     */
    public void setMessage (String message) {
        this.message = message;
        messageAttribute = true;
    }

    /**
     * Defines the default value of the property to be created from input.
     * Property value will be set to default if not input is received.
     *
     * @param defaultvalue Default value for the property if no input
     * is received
     */
    public void setDefaultvalue (String defaultvalue) {
        this.defaultvalue = defaultvalue;
    }

    /**
     * Set a multiline message.
     * @param msg The message to be displayed.
     */
    public void addText(String msg) {
        if (messageAttribute && "".equals(msg.trim())) {
            return;
        }
        message += getProject().replaceProperties(msg);
    }

    /**
     * No arg constructor.
     */
    public Input () {
    }

    /**
     * Actual method executed by ant.
     * @throws BuildException on error
     */
    public void execute () throws BuildException {
        if (addproperty != null
            && getProject().getProperty(addproperty) != null) {
            log("skipping " + getTaskName() + " as property " + addproperty
                + " has already been set.");
            return;
        }

        InputRequest request = null;
        if (validargs != null) {
            Vector accept = StringUtils.split(validargs, ',');
            request = new MultipleChoiceInputRequest(message, accept);
        } else {
            request = new InputRequest(message);
        }
        request.setDefaultValue(defaultvalue);

        InputHandler h = handler == null
            ? getProject().getInputHandler()
            : handler.getInputHandler();

        h.handleInput(request);

        String value = request.getInput();
        if ((value == null || value.trim().length() == 0)
            && defaultvalue != null) {
            value = defaultvalue;
        }
        if (addproperty != null && value != null) {
            getProject().setNewProperty(addproperty, value);
        }
    }

    /**
     * Create a nested handler element.
     * @return a Handler for this Input task.
     */
    public Handler createHandler() {
        if (handler != null) {
            throw new BuildException(
                "Cannot define > 1 nested input handler");
        }
        handler = new Handler();
        return handler;
    }

}