openjpa-lib/src/main/java/org/apache/openjpa/lib/meta/ZipFileMetaDataIterator.java

/*
 * 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.openjpa.lib.meta;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

import org.apache.openjpa.lib.util.J2DoPrivHelper;

/**
 * Iterator over all metadata resources in a given zip file.
 *
 * @author Abe White
 */
public class ZipFileMetaDataIterator
    implements MetaDataIterator, MetaDataFilter.Resource {

    private final ZipFile _file;
    private final MetaDataFilter _filter;
    private final Enumeration<? extends ZipEntry> _entries;
    private ZipEntry _entry = null;
    private ZipEntry _last = null;

    /**
     * Constructor; supply zip/jar URL and optional file filter.
     */
    public ZipFileMetaDataIterator(URL url, MetaDataFilter filter)
        throws IOException {
        if (url == null) {
            _file = null;
        } else {
            URLConnection con = url.openConnection();
            con.setDefaultUseCaches(false);
            try {
                _file = (ZipFile) AccessController.doPrivileged(
                    J2DoPrivHelper.getContentAction(con));
            } catch (PrivilegedActionException pae) {
                 throw (IOException) pae.getException();
            }
        }
        _filter = filter;
        _entries = (_file == null) ? null : _file.entries();
    }

    /**
     * Constructor; supply zip file and optional file filter.
     */
    public ZipFileMetaDataIterator(ZipFile file, MetaDataFilter filter) {
        _file = file;
        _filter = filter;
        _entries = (file == null) ? null : file.entries();
    }

    public boolean hasNext() throws IOException {
        if (_entries == null)
            return false;

        // search for next metadata file
        while (_entry == null && _entries.hasMoreElements()) {
            _entry = _entries.nextElement();
            if (_filter != null && !_filter.matches(this))
                _entry = null;
        }
        return _entry != null;
    }

    public String next() throws IOException {
        if (!hasNext())
            throw new NoSuchElementException();
        String ret = _entry.getName();
        _last = _entry;
        _entry = null;
        return ret;
    }

    public InputStream getInputStream() throws IOException {
        if (_last == null)
            throw new IllegalStateException();
        return _file.getInputStream(_last);
    }

    public File getFile() {
        if (_last == null)
            throw new IllegalStateException();
        return null;
    }

    public void close() {
        try {
           if (_file != null)
               _file.close();
        } catch (IOException ioe) {
        }
    }

    //////////////////////////////////////////
    // MetaDataFilter.Resource implementation
    //////////////////////////////////////////

    public String getName() {
        return _entry.getName();
    }

    public byte[] getContent() throws IOException {
        long size = _entry.getSize();
        if (size == 0)
            return new byte[0];

        InputStream in = _file.getInputStream(_entry);
        byte[] content;
        if (size < 0) {
            ByteArrayOutputStream bout = new ByteArrayOutputStream();
            byte[] buf = new byte[1024];
            for (int r; (r = in.read(buf)) != -1; bout.write(buf, 0, r)) ;
            content = bout.toByteArray();
        } else {
            content = new byte[(int) size];
            int offset = 0;
            int read;
            while (offset < size &&
                (read = in.read(content, offset, (int) size - offset)) != -1) {
                offset += read;
            }
        }
        in.close();
        return content;
    }
}