Commons FileUpload example source code file (Streams.java)

This example Commons FileUpload source code file (Streams.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 - Commons FileUpload tags/keywords

bytearrayoutputstream, bytearrayoutputstream, default_buffer_size, inputstream, io, ioexception, ioexception, outputstream, outputstream, streams, string, string, throwable

The Commons FileUpload Streams.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.commons.fileupload.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


/** Utility class for working with streams.
 */
public final class Streams {
    /**
     * Private constructor, to prevent instantiation.
     * This class has only static methods.
     */
    private Streams() {
        // Does nothing
    }

    /**
     * Default buffer size for use in
     * {@link #copy(InputStream, OutputStream, boolean)}.
     */
    private static final int DEFAULT_BUFFER_SIZE = 8192;

    /**
     * Copies the contents of the given {@link InputStream}
     * to the given {@link OutputStream}. Shortcut for
     * <pre>
     *   copy(pInputStream, pOutputStream, new byte[8192]);
     * </pre>
     * @param pInputStream The input stream, which is being read.
     * It is guaranteed, that {@link InputStream#close()} is called
     * on the stream.
     * @param pOutputStream The output stream, to which data should
     * be written. May be null, in which case the input streams
     * contents are simply discarded.
     * @param pClose True guarantees, that {@link OutputStream#close()}
     * is called on the stream. False indicates, that only
     * {@link OutputStream#flush()} should be called finally.
     *
     * @return Number of bytes, which have been copied.
     * @throws IOException An I/O error occurred.
     */
    public static long copy(InputStream pInputStream,
            OutputStream pOutputStream, boolean pClose)
            throws IOException {
        return copy(pInputStream, pOutputStream, pClose,
                new byte[DEFAULT_BUFFER_SIZE]);
    }

    /**
     * Copies the contents of the given {@link InputStream}
     * to the given {@link OutputStream}.
     * @param pIn The input stream, which is being read.
     *   It is guaranteed, that {@link InputStream#close()} is called
     *   on the stream.
     * @param pOut The output stream, to which data should
     *   be written. May be null, in which case the input streams
     *   contents are simply discarded.
     * @param pClose True guarantees, that {@link OutputStream#close()}
     *   is called on the stream. False indicates, that only
     *   {@link OutputStream#flush()} should be called finally.
     * @param pBuffer Temporary buffer, which is to be used for
     *   copying data.
     * @return Number of bytes, which have been copied.
     * @throws IOException An I/O error occurred.
     */
    public static long copy(InputStream pIn,
            OutputStream pOut, boolean pClose,
            byte[] pBuffer)
    throws IOException {
        OutputStream out = pOut;
        InputStream in = pIn;
        try {
            long total = 0;
            for (;;) {
                int res = in.read(pBuffer);
                if (res == -1) {
                    break;
                }
                if (res > 0) {
                    total += res;
                    if (out != null) {
                        out.write(pBuffer, 0, res);
                    }
                }
            }
            if (out != null) {
                if (pClose) {
                    out.close();
                } else {
                    out.flush();
                }
                out = null;
            }
            in.close();
            in = null;
            return total;
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (Throwable t) {
                    /* Ignore me */
                }
            }
            if (pClose  &&  out != null) {
                try {
                    out.close();
                } catch (Throwable t) {
                    /* Ignore me */
                }
            }
        }
    }

    /**
     * This convenience method allows to read a
     * {@link org.apache.commons.fileupload.FileItemStream}'s
     * content into a string. The platform's default character encoding
     * is used for converting bytes into characters.
     * @param pStream The input stream to read.
     * @see #asString(InputStream, String)
     * @return The streams contents, as a string.
     * @throws IOException An I/O error occurred.
     */
    public static String asString(InputStream pStream) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        copy(pStream, baos, true);
        return baos.toString();
    }

    /**
     * This convenience method allows to read a
     * {@link org.apache.commons.fileupload.FileItemStream}'s
     * content into a string, using the given character encoding.
     * @param pStream The input stream to read.
     * @param pEncoding The character encoding, typically "UTF-8".
     * @see #asString(InputStream)
     * @return The streams contents, as a string.
     * @throws IOException An I/O error occurred.
     */
    public static String asString(InputStream pStream, String pEncoding)
            throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        copy(pStream, baos, true);
        return baos.toString(pEncoding);
    }
}