Ant example source code file (URLResource.java)

This example Ant source code file (URLResource.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, httpurlconnection, io, ioexception, ioexception, jar, jarurlconnection, malformedurlexception, net, network, null_url, resource, resource, string, url, url, urlresource, urlresource

The URLResource.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.types.resources;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.net.MalformedURLException;
import java.net.JarURLConnection;
import java.util.jar.JarFile;

import org.apache.tools.ant.Project;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.Reference;
import org.apache.tools.ant.util.FileUtils;

/**
 * Exposes a URL as a Resource.
 * @since Ant 1.7
 */
public class URLResource extends Resource {
    private static final FileUtils FILE_UTILS = FileUtils.getFileUtils();
    private static final int NULL_URL
        = Resource.getMagicNumber("null URL".getBytes());

    private URL url;
    private URLConnection conn;

    /**
     * Default constructor.
     */
    public URLResource() {
    }

    /**
     * Convenience constructor.
     * @param u the URL to expose.
     */
    public URLResource(URL u) {
        setURL(u);
    }

    /**
     * Convenience constructor.
     * @param f the File to set as a URL.
     */
    public URLResource(File f) {
        setFile(f);
    }

    /**
     * String constructor for Ant attribute introspection.
     * @param u String representation of this URL.
     * @see org.apache.tools.ant.IntrospectionHelper
     */
    public URLResource(String u) {
        this(newURL(u));
    }

    /**
     * Set the URL for this URLResource.
     * @param u the URL to expose.
     */
    public synchronized void setURL(URL u) {
        checkAttributesAllowed();
        url = u;
    }

    /**
     * Set the URL from a File.
     * @param f the File to set as a URL.
     */
    public synchronized void setFile(File f) {
        try {
            setURL(FILE_UTILS.getFileURL(f));
        } catch (MalformedURLException e) {
            throw new BuildException(e);
        }
    }

    /**
     * Get the URL used by this URLResource.
     * @return a URL object.
     */
    public synchronized URL getURL() {
        if (isReference()) {
            return ((URLResource) getCheckedRef()).getURL();
        }
        return url;
     }

    /**
     * Overrides the super version.
     * @param r the Reference to set.
     */
    public synchronized void setRefid(Reference r) {
        //not using the accessor in this case to avoid side effects
        if (url != null) {
            throw tooManyAttributes();
        }
        super.setRefid(r);
    }

    /**
     * Get the name of this URLResource
     * (its file component minus the leading separator).
     * @return the name of this resource.
     */
    public synchronized String getName() {
        return isReference() ? ((Resource) getCheckedRef()).getName()
            : getURL().getFile().substring(1);
    }

    /**
     * Return this URLResource formatted as a String.
     * @return a String representation of this URLResource.
     */
    public synchronized String toString() {
        return isReference()
            ? getCheckedRef().toString() : String.valueOf(getURL());
    }

    /**
     * Find out whether the URL exists .
     * @return true if this resource exists.
     */
    public synchronized boolean isExists() {
        if (isReference()) {
            return ((Resource) getCheckedRef()).isExists();
        }
        return isExists(false);
    }

    /**
     * Find out whether the URL exists, and close the connection
     * opened to the URL if closeConnection is true.
     *
     * Note that this method does ensure that if:
     * - the resource exists (if it returns true)
     * - and if the current object is not a reference
     * (isReference() returns false)
     * - and if it was called with closeConnection to false,
     *
     * then the connection to the URL (stored in the conn
     * private field) will be opened, and require to be closed
     * by the caller.
     *
     * @param closeConnection true if the connection should be closed
     * after the call, false if it should stay open.
     * @return true if this resource exists.
     */
    private synchronized boolean isExists(boolean closeConnection) {
        if (getURL() == null) {
            return false;
        }
        try {
            connect();
            return true;
        } catch (IOException e) {
            return false;
        } finally {
            if (closeConnection) {
                close();
            }
        }
    }


    /**
     * Tells the modification time in milliseconds since 01.01.1970 .
     *
     * @return 0 if the resource does not exist to mirror the behavior
     * of {@link java.io.File File}.
     */
    public synchronized long getLastModified() {
        if (isReference()) {
            return ((Resource) getCheckedRef()).getLastModified();
        }
        if (!isExists(false)) {
            return 0L;
        }
        return conn.getLastModified();
    }

    /**
     * Tells if the resource is a directory.
     * @return boolean whether the resource is a directory.
     */
    public synchronized boolean isDirectory() {
        return isReference()
            ? ((Resource) getCheckedRef()).isDirectory()
            : getName().endsWith("/");
    }

    /**
     * Get the size of this Resource.
     * @return the size, as a long, 0 if the Resource does not exist (for
     *         compatibility with java.io.File), or UNKNOWN_SIZE if not known.
     */
    public synchronized long getSize() {
        if (isReference()) {
            return ((Resource) getCheckedRef()).getSize();
        }
        if (!isExists(false)) {
            return 0L;
        }
        try {
            connect();
            long contentlength = conn.getContentLength();
            close();
            return contentlength;
        } catch (IOException e) {
            return UNKNOWN_SIZE;
        }
    }

    /**
     * Test whether an Object equals this URLResource.
     * @param another the other Object to compare.
     * @return true if the specified Object is equal to this Resource.
     */
    public synchronized boolean equals(Object another) {
        if (this == another) {
            return true;
        }
        if (isReference()) {
            return getCheckedRef().equals(another);
        }
        if (!(another.getClass().equals(getClass()))) {
            return false;
        }
        URLResource otheru = (URLResource) another;
        return getURL() == null
            ? otheru.getURL() == null
            : getURL().equals(otheru.getURL());
    }

    /**
     * Get the hash code for this Resource.
     * @return hash code as int.
     */
    public synchronized int hashCode() {
        if (isReference()) {
            return getCheckedRef().hashCode();
        }
        return MAGIC * ((getURL() == null) ? NULL_URL : getURL().hashCode());
    }

    /**
     * Get an InputStream for the Resource.
     * @return an InputStream containing this Resource's content.
     * @throws IOException if unable to provide the content of this
     *         Resource as a stream.
     * @throws UnsupportedOperationException if InputStreams are not
     *         supported for this Resource type.
     */
    public synchronized InputStream getInputStream() throws IOException {
        if (isReference()) {
            return ((Resource) getCheckedRef()).getInputStream();
        }
        connect();
        try {
            return conn.getInputStream();
        } finally {
            conn = null;
        }
    }

    /**
     * Get an OutputStream for the Resource.
     * @return an OutputStream to which content can be written.
     * @throws IOException if unable to provide the content of this
     *         Resource as a stream.
     * @throws UnsupportedOperationException if OutputStreams are not
     *         supported for this Resource type.
     * @throws IOException if the URL cannot be opened.
     */
    public synchronized OutputStream getOutputStream() throws IOException {
        if (isReference()) {
            return ((Resource) getCheckedRef()).getOutputStream();
        }
        connect();
        try {
            return conn.getOutputStream();
        } finally {
            conn = null;
        }
    }

    /**
     * Ensure that we have a connection.
     * @throws IOException if the connection cannot be established.
     */
    protected synchronized void connect() throws IOException {
        URL u = getURL();
        if (u == null) {
            throw new BuildException("URL not set");
        }
        if (conn == null) {
            try {
                conn = u.openConnection();
                conn.connect();
            } catch (IOException e) {
                log(e.toString(), Project.MSG_ERR);
                conn = null;
                throw e;
            }
        }
    }

    /**
     * Closes the URL connection if:
     * - it is opened (i.e. the field conn is not null)
     * - this type of URLConnection supports some sort of close mechanism
     *
     * This method ensures the field conn will be null after the call.
     *
     */
    private synchronized void close() {
        if (conn != null) {
            try {
                if (conn instanceof JarURLConnection) {
                    JarURLConnection juc = (JarURLConnection) conn;
                    JarFile jf = juc.getJarFile();
                    jf.close();
                    jf = null;
                } else if (conn instanceof HttpURLConnection) {
                    ((HttpURLConnection) conn).disconnect();
                }
            } catch (IOException exc) {
                //ignore
            } finally {
                conn = null;
            }
        }
    }

    private static URL newURL(String u) {
        try {
            return new URL(u);
        } catch (MalformedURLException e) {
            throw new BuildException(e);
        }
    }

}