Ant example source code file (LoadResource.java)

This example Ant source code file (LoadResource.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

bufferedinputstream, buildexception, buildexception, chainreaderhelper, chainreaderhelper, inputstream, inputstreamreader, io, reader, resource, resource, string, string, task, util, vector

The LoadResource.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.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.Vector;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.filters.util.ChainReaderHelper;
import org.apache.tools.ant.types.FilterChain;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.util.FileUtils;

/**
 * Load a resource into a property
 *
 * @since Ant 1.7
 * @ant.task category="utility"
 */
public class LoadResource extends Task {

    /**
     * The resource to load.
     */
    private Resource src;

    /**
     * what to do when it goes pear-shaped
     */
    private boolean failOnError = true;

    /**
     * suppress error message if it goes pear-shaped, sets failOnError=false
     */
    private boolean quiet = false;

    /**
     * Encoding to use for filenames, defaults to the platform's default
     * encoding.
     */
    private String encoding = null;

    /**
     * name of property
     */
    private String property = null;

    /**
     * Holds FilterChains
     */
    private final Vector filterChains = new Vector();

    /**
     * Encoding to use for input, defaults to the platform's default
     * encoding. <p>
     *
     * For a list of possible values see
     * <a href="http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html">
     * http://java.sun.com/j2se/1.5.0/docs/guide/intl/encoding.doc.html
     * </a>.

     *
     * @param encoding The new Encoding value
     */

    public final void setEncoding(final String encoding) {
        this.encoding = encoding;
    }


    /**
     * Property name to save to.
     *
     * @param property The new Property value
     */
    public final void setProperty(final String property) {
        this.property = property;
    }

    /**
     * If true, fail on load error.
     *
     * @param fail The new Failonerror value
     */
    public final void setFailonerror(final boolean fail) {
        failOnError = fail;
    }

    /**
     * If true, suppress the load error report and set the
     * the failonerror value to false.
     * @param quiet The new Quiet value
     */
    public void setQuiet(final boolean quiet) {
        this.quiet = quiet;
        if (quiet) {
            this.failOnError = false;
        }
    }

    /**
     * read in a source file to a property
     *
     * @exception BuildException if something goes wrong with the build
     */
    public final void execute()
        throws BuildException {
        //validation
        if (src == null) {
            throw new BuildException("source resource not defined");
        }
        if (property == null) {
            throw new BuildException("output property not defined");
        }
        if (quiet && failOnError) {
            throw new BuildException("quiet and failonerror cannot both be "
                                     + "set to true");
        }
        if (!src.isExists()) {
            String message = src + " doesn't exist";
            if (failOnError) {
                throw new BuildException(message);
            } else {
                log(message, quiet ? Project.MSG_WARN : Project.MSG_ERR);
                return;
            }
        }
        InputStream is = null;
        BufferedInputStream bis = null;
        Reader instream = null;
        log("loading " + src + " into property " + property,
            Project.MSG_VERBOSE);
        try {
            final long len = src.getSize();
            log("resource size = "
                + (len != Resource.UNKNOWN_SIZE ? String.valueOf(len)
                   : "unknown"), Project.MSG_DEBUG);
            //discard most of really big resources
            final int size = (int) len;
            //open up the resource
            is = src.getInputStream();
            bis = new BufferedInputStream(is);
            if (encoding == null) {
                instream = new InputStreamReader(bis);
            } else {
                instream = new InputStreamReader(bis, encoding);
            }

            String text = "";
            if (size != 0) {
                ChainReaderHelper crh = new ChainReaderHelper();
                if (len != Resource.UNKNOWN_SIZE) {
                    crh.setBufferSize(size);
                }
                crh.setPrimaryReader(instream);
                crh.setFilterChains(filterChains);
                crh.setProject(getProject());
                instream = crh.getAssembledReader();

                text = crh.readFully(instream);
            }

            if (text != null) {
                if (text.length() > 0) {
                    getProject().setNewProperty(property, text);
                    log("loaded " + text.length() + " characters",
                        Project.MSG_VERBOSE);
                    log(property + " := " + text, Project.MSG_DEBUG);
                }
            }

        } catch (final IOException ioe) {
            final String message = "Unable to load resource: "
                + ioe.toString();
            if (failOnError) {
                throw new BuildException(message, ioe, getLocation());
            } else {
                log(message, quiet ? Project.MSG_VERBOSE : Project.MSG_ERR);
            }
        } catch (final BuildException be) {
            if (failOnError) {
                throw be;
            } else {
                log(be.getMessage(),
                    quiet ? Project.MSG_VERBOSE : Project.MSG_ERR);
            }
        } finally {
            FileUtils.close(is);
        }
    }

    /**
     * Add the FilterChain element.
     * @param filter the filter to add
     */
    public final void addFilterChain(FilterChain filter) {
        filterChains.addElement(filter);
    }

    /**
     * Set the source resource.
     * @param a the resource to load as a single element Resource collection.
     */
    public void addConfigured(ResourceCollection a) {
        if (a.size() != 1) {
            throw new BuildException("only single argument resource collections"
                                     + " are supported");
        }
        src = (Resource) a.iterator().next();
    }

}