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 *
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 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * http://glassfish.java.net/public/CDDL+GPL_1_1.html
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 * GPL Classpath Exception:
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 */
package org.glassfish.jersey.message.internal;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.Charset;
import java.security.AccessController;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.ws.rs.core.MediaType;

import org.glassfish.jersey.internal.util.PropertiesHelper;
import org.glassfish.jersey.message.MessageProperties;

/**
 * A utility class for reading and writing using byte and character streams.
 * <p>
 * If a byte or character array is utilized then the size of the array
 * is by default the value of {@value org.glassfish.jersey.message.MessageProperties#IO_DEFAULT_BUFFER_SIZE}.
 * This value can be set using the system property
 * {@value org.glassfish.jersey.message.MessageProperties#IO_BUFFER_SIZE}.
 *
 * @author Paul Sandoz
 */
public final class ReaderWriter {

    private static final Logger LOGGER = Logger.getLogger(ReaderWriter.class.getName());
    /**
     * The UTF-8 Charset.
     */
    public static final Charset UTF8 = Charset.forName("UTF-8");
    /**
     * The buffer size for arrays of byte and character.
     */
    public static final int BUFFER_SIZE = getBufferSize();

    private static int getBufferSize() {
        // TODO should we unify this buffer size and CommittingOutputStream buffer size (controlled by CommonProperties.OUTBOUND_CONTENT_LENGTH_BUFFER)?
        final String value = AccessController.doPrivileged(PropertiesHelper.getSystemProperty(MessageProperties.IO_BUFFER_SIZE));
        if (value != null) {
            try {
                final int i = Integer.parseInt(value);
                if (i <= 0) {
                    throw new NumberFormatException("Value not positive.");
                }
                return i;
            } catch (NumberFormatException e) {
                LOGGER.log(Level.CONFIG,
                        "Value of " + MessageProperties.IO_BUFFER_SIZE
                        + " property is not a valid positive integer [" + value + "]."
                        + " Reverting to default [" + MessageProperties.IO_DEFAULT_BUFFER_SIZE + "].",
                        e);
            }
        }
        return MessageProperties.IO_DEFAULT_BUFFER_SIZE;
    }

    /**
     * Read bytes from an input stream and write them to an output stream.
     *
     * @param in the input stream to read from.
     * @param out the output stream to write to.
     * @throws IOException if there is an error reading or writing bytes.
     */
    public static void writeTo(InputStream in, OutputStream out) throws IOException {
        int read;
        final byte[] data = new byte[BUFFER_SIZE];
        while ((read = in.read(data)) != -1) {
            out.write(data, 0, read);
        }
    }

    /**
     * Read characters from an input stream and write them to an output stream.
     *
     * @param in the reader to read from.
     * @param out the writer to write to.
     * @throws IOException if there is an error reading or writing characters.
     */
    public static void writeTo(Reader in, Writer out) throws IOException {
        int read;
        final char[] data = new char[BUFFER_SIZE];
        while ((read = in.read(data)) != -1) {
            out.write(data, 0, read);
        }
    }

    /**
     * Get the character set from a media type.
     * <p>
     * The character set is obtained from the media type parameter "charset".
     * If the parameter is not present the {@link #UTF8} charset is utilized.
     *
     * @param m the media type.
     * @return the character set.
     */
    public static Charset getCharset(MediaType m) {
        String name = (m == null) ? null : m.getParameters().get("charset");
        return (name == null) ? UTF8 : Charset.forName(name);
    }

    /**
     * Read the bytes of an input stream and convert to a string.
     *
     * @param in the input stream to read from.
     * @param type the media type that determines the character set defining
     *        how to decode bytes to charaters.
     * @return the string.
     * @throws IOException if there is an error reading from the input stream.
     */
    public static String readFromAsString(InputStream in,
            MediaType type) throws IOException {
        return readFromAsString(new InputStreamReader(in, getCharset(type)));
    }

    /**
     * Read the characters of a reader and convert to a string.
     *
     * @param reader the reader
     * @return the string
     * @throws IOException if there is an error reading from the reader.
     */
    public static String readFromAsString(Reader reader) throws IOException {
        StringBuilder sb = new StringBuilder();
        char[] c = new char[BUFFER_SIZE];
        int l;
        while ((l = reader.read(c)) != -1) {
            sb.append(c, 0, l);
        }
        return sb.toString();
    }

    /**
     * Convert a string to bytes and write those bytes to an output stream.
     *
     * @param s the string to convert to bytes.
     * @param out the output stream to write to.
     * @param type the media type that determines the character set defining
     *        how to decode bytes to characters.
     * @throws IOException
     */
    public static void writeToAsString(String s, OutputStream out,
            MediaType type) throws IOException {
        Writer osw = new BufferedWriter(new OutputStreamWriter(out,
                getCharset(type)));
        osw.write(s, 0, s.length()); // MUCH faster than BufferedWriter.write(s) on JDK 1.6
        osw.flush();
    }

    /**
     * Prevents instantiation.
     */
    private ReaderWriter() {
    }
}
