convert Reader to InputStream : Reader « File « Java Tutorial






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import java.io.*;


/**
* This class convert Reader to InputStream. It works by converting
* the characters to the encoding specified in constructor parameter.
*
* @author   Petr Hamernik, David Strupl
*/
public class ReaderInputStream extends InputStream {
    /** Input Reader class. */
    private Reader reader;
    private PipedOutputStream pos;
    private PipedInputStream pis;
    private OutputStreamWriter osw;

    /** Creates new input stream from the given reader.
     * Uses the platform default encoding.
    * @param reader Input reader
    */
    public ReaderInputStream(Reader reader) throws IOException {
        this.reader = reader;
        pos = new PipedOutputStream();
        pis = new PipedInputStream(pos);
        osw = new OutputStreamWriter(pos);
    }

    /** Creates new input stream from the given reader and encoding.
     * @param reader Input reader
     * @param encoding
     */
    public ReaderInputStream(Reader reader, String encoding)
    throws IOException {
        this.reader = reader;
        pos = new PipedOutputStream();
        pis = new PipedInputStream(pos);
        osw = new OutputStreamWriter(pos, encoding);
    }

    public int read() throws IOException {
        if (pis.available() > 0) {
            return pis.read();
        }

        int c = reader.read();

        if (c == -1) {
            return c;
        }

        osw.write(c);
        osw.flush();
        pos.flush();

        return pis.read();
    }

    public int read(byte[] b, int off, int len) throws IOException {
        if (len == 0) {
            return 0;
        }

        int c = read();

        if (c == -1) {
            return -1;
        }

        b[off] = (byte) c;

        int i = 1;

        // Don't try to fill up the buffer if the reader is waiting.
        for (; (i < len) && reader.ready(); i++) {
            c = read();

            if (c == -1) {
                return i;
            }

            b[off + i] = (byte) c;
        }

        return i;
    }

    public int available() throws IOException {
        int i = pis.available();

        if (i > 0) {
            return i;
        }

        if (reader.ready()) {
            // Char must produce at least one byte.
            return 1;
        } else {
            return 0;
        }
    }

    public void close() throws IOException {
        reader.close();
        osw.close();
        pis.close();
    }
}








11.29.Reader
11.29.1.Read and return the entire contents of the supplied Reader. This method always closes the reader when finished reading.
11.29.2.Read from Reader and write to Writer until there is no more input from reader.
11.29.3.Reads characters available from the Reader and returns these characters as a String object.
11.29.4.Transfers all characters that can be read from one Reader to another Reader
11.29.5.Writes all characters from a Reader to a file using the default character encoding.
11.29.6.convert Reader to InputStream
11.29.7.Compare the contents of two Readers to determine if they are equal or not.
11.29.8.An InputStream backed by a Reader
11.29.9.Reader: Reading Text (Characters)
11.29.10.UTF8 Reader
11.29.11.CRLF Terminated Reader