Ant example source code file (Length.java)

This example Ant source code file (Length.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

all, allhandler, allhandler, buildexception, buildexception, conditionhandler, eachhandler, handler, io, long, long, printstream, resources, string, string, util

The Length.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.io.File;
import java.io.PrintStream;
import java.io.OutputStream;
import java.util.Iterator;

import org.apache.tools.ant.Task;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.taskdefs.condition.Condition;
import org.apache.tools.ant.types.FileSet;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.Comparison;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.types.EnumeratedAttribute;
import org.apache.tools.ant.types.resources.Resources;
import org.apache.tools.ant.types.resources.FileResource;
import org.apache.tools.ant.util.PropertyOutputStream;

/**
 * Gets lengths:  of files/resources, byte size; of strings, length (optionally trimmed).
 * The task is overloaded in this way for semantic reasons, much like Available.
 * @since Ant 1.6.3
 */
public class Length extends Task implements Condition {

    private static final String ALL = "all";
    private static final String EACH = "each";
    private static final String STRING = "string";

    private static final String LENGTH_REQUIRED
        = "Use of the Length condition requires that the length attribute be set.";

    private String property;
    private String string;
    private Boolean trim;
    private String mode = ALL;
    private Comparison when = Comparison.EQUAL;
    private Long length;
    private Resources resources;

    /**
     * The property in which the length will be stored.
     * @param property the <code>String property key.
     */
    public synchronized void setProperty(String property) {
        this.property = property;
    }

    /**
     * Set the single file for this task.
     * @param file the <code>File whose length to retrieve.
     */
    public synchronized void setFile(File file) {
        add(new FileResource(file));
    }

    /**
     * Add a FileSet.
     * @param fs the <code>FileSet to add.
     */
    public synchronized void add(FileSet fs) {
        add((ResourceCollection) fs);
    }

    /**
     * Add a ResourceCollection.
     * @param c the <code>ResourceCollection to add.
     * @since Ant 1.7
     */
    public synchronized void add(ResourceCollection c) {
        if (c == null) {
            return;
        }
        resources = (resources == null) ? new Resources() : resources;
        resources.add(c);
    }

    /**
     * Set the target count number for use as a Condition.
     * @param ell the long length to compare with.
     */
    public synchronized void setLength(long ell) {
        length = new Long(ell);
    }

    /**
     * Set the comparison for use as a Condition.
     * @param w EnumeratedAttribute When.
     * @see org.apache.tools.ant.types.Comparison
     */
    public synchronized void setWhen(When w) {
        setWhen((Comparison) w);
    }

    /**
     * Set the comparison for use as a Condition.
     * @param c Comparison.
     * @see org.apache.tools.ant.types.Comparison
     * @since Ant 1.7
     */
    public synchronized void setWhen(Comparison c) {
        when = c;
    }

    /**
     * Set the execution mode for working with files.
     * @param m the <code>FileMode to use.
     */
    public synchronized void setMode(FileMode m) {
        this.mode = m.getValue();
    }

    /**
     * Set the string whose length to get.
     * @param string <code>String.
     */
    public synchronized void setString(String string) {
        this.string = string;
        this.mode = STRING;
    }

    /**
     * Set whether to trim in string mode.
     * @param trim <code>boolean.
     */
    public synchronized void setTrim(boolean trim) {
        this.trim = trim ? Boolean.TRUE : Boolean.FALSE;
    }

    /**
     * Learn whether strings will be trimmed.
     * @return boolean trim setting.
     */
    public boolean getTrim() {
        return trim != null && trim.booleanValue();
    }

    /**
     * Execute the length task.
     */
    public void execute() {
        validate();
        PrintStream ps = new PrintStream((property != null)
            ? (OutputStream) new PropertyOutputStream(getProject(), property)
            : (OutputStream) new LogOutputStream(this, Project.MSG_INFO));

        if (STRING.equals(mode)) {
            ps.print(getLength(string, getTrim()));
            ps.close();
        } else if (EACH.equals(mode)) {
            handleResources(new EachHandler(ps));
        } else if (ALL.equals(mode)) {
            handleResources(new AllHandler(ps));
        }
    }

    /**
     * Fulfill the condition contract.
     * @return true if the condition is true.
     * @throws BuildException if an error occurs.
     */
    public boolean eval() {
        validate();
        if (length == null) {
            throw new BuildException(LENGTH_REQUIRED);
        }
        Long ell = null;
        if (STRING.equals(mode)) {
            ell = new Long(getLength(string, getTrim()));
        } else {
            ConditionHandler h = new ConditionHandler();
            handleResources(h);
            ell = new Long(h.getLength());
        }
        return when.evaluate(ell.compareTo(length));
    }

    private void validate() {
        if (string != null) {
            if (resources != null) {
                throw new BuildException("the string length function"
                    + " is incompatible with the file/resource length function");
            }
            if (!(STRING.equals(mode))) {
                throw new BuildException("the mode attribute is for use"
                    + " with the file/resource length function");
            }
        } else if (resources != null) {
            if (!(EACH.equals(mode) || ALL.equals(mode))) {
                throw new BuildException("invalid mode setting for"
                    + " file/resource length function: \"" + mode + "\"");
            } else if (trim != null) {
                throw new BuildException("the trim attribute is"
                    + " for use with the string length function only");
            }
        } else {
            throw new BuildException("you must set either the string attribute"
                + " or specify one or more files using the file attribute or"
                + " nested resource collections");
        }
    }

    private void handleResources(Handler h) {
        for (Iterator i = resources.iterator(); i.hasNext();) {
            Resource r = (Resource) i.next();
            if (!r.isExists()) {
                log(r + " does not exist", Project.MSG_ERR);
            } else if (r.isDirectory()) {
                log(r + " is a directory; length unspecified",
                    Project.MSG_ERR);
            } else {
                h.handle(r);
            }
        }
        h.complete();
    }

    private static long getLength(String s, boolean t) {
        return (t ? s.trim() : s).length();
    }

    /** EnumeratedAttribute operation mode */
    public static class FileMode extends EnumeratedAttribute {
        static final String[] MODES = new String[] {EACH, ALL};

        /**
         * Return the possible values for FileMode.
         * @return <code>String[].
         */
        public String[] getValues() {
            return MODES;
        }

    }

    /**
     * EnumeratedAttribute for the when attribute.
     */
    public static class When extends Comparison {
        //extend Comparison; retain for BC only
    }

    private abstract class Handler {
        private PrintStream ps;
        Handler(PrintStream ps) {
            this.ps = ps;
        }

        protected PrintStream getPs() {
            return ps;
        }

        protected abstract void handle(Resource r);

        void complete() {
            ps.close();
        }
    }

    private class EachHandler extends Handler {
        EachHandler(PrintStream ps) {
            super(ps);
        }
        protected void handle(Resource r) {
            getPs().print(r.toString());
            getPs().print(" : ");
            //when writing to the log, we'll see what's happening:
            long size = r.getSize();
            if (size == Resource.UNKNOWN_SIZE) {
                getPs().println("unknown");
            } else {
                getPs().println(size);
            }
       }
    }

    private class AllHandler extends Handler {
        private long accum = 0L;
        AllHandler(PrintStream ps) {
            super(ps);
        }
        protected long getAccum() {
            return accum;
        }
        protected synchronized void handle(Resource r) {
            long size = r.getSize();
            if (size == Resource.UNKNOWN_SIZE) {
                log("Size unknown for " + r.toString(), Project.MSG_WARN);
            } else {
                accum += size;
            }
        }
        void complete() {
            getPs().print(accum);
            super.complete();
        }
    }

    private class ConditionHandler extends AllHandler {
        ConditionHandler() {
            super(null);
        }
        void complete() {
        }
        long getLength() {
            return getAccum();
        }
    }
}