Ant example source code file (ReaderInputStream.java)

This example Ant source code file (ReaderInputStream.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

closed, closed, illegalargumentexception, inputstream, io, ioexception, ioexception, reader, readerinputstream, stream, stream, string, string

The ReaderInputStream.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.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;

/**
 * Adapts a <code>Reader as an InputStream.
 * Adapted from <code>StringInputStream.
 *
 */
public class ReaderInputStream extends InputStream {

    /** Source Reader */
    private Reader in;

    private String encoding = System.getProperty("file.encoding");

    private byte[] slack;

    private int begin;

    /**
     * Construct a <code>ReaderInputStream
     * for the specified <code>Reader.
     *
     * @param reader   <code>Reader.  Must not be null.
     */
    public ReaderInputStream(Reader reader) {
        in = reader;
    }

    /**
     * Construct a <code>ReaderInputStream
     * for the specified <code>Reader,
     * with the specified encoding.
     *
     * @param reader     non-null <code>Reader.
     * @param encoding   non-null <code>String encoding.
     */
    public ReaderInputStream(Reader reader, String encoding) {
        this(reader);
        if (encoding == null) {
            throw new IllegalArgumentException("encoding must not be null");
        } else {
            this.encoding = encoding;
        }
    }

    /**
     * Reads from the <code>Reader, returning the same value.
     *
     * @return the value of the next character in the <code>Reader.
     *
     * @exception IOException if the original <code>Reader fails to be read
     */
    public synchronized int read() throws IOException {
        if (in == null) {
            throw new IOException("Stream Closed");
        }

        byte result;
        if (slack != null && begin < slack.length) {
            result = slack[begin];
            if (++begin == slack.length) {
                slack = null;
            }
        } else {
            byte[] buf = new byte[1];
            if (read(buf, 0, 1) <= 0) {
                return -1;
            } else {
                result = buf[0];
            }
        }

        return result & 0xFF;
    }

    /**
     * Reads from the <code>Reader into a byte array
     *
     * @param b  the byte array to read into
     * @param off the offset in the byte array
     * @param len the length in the byte array to fill
     * @return the actual number read into the byte array, -1 at
     *         the end of the stream
     * @exception IOException if an error occurs
     */
    public synchronized int read(byte[] b, int off, int len)
        throws IOException {
        if (in == null) {
            throw new IOException("Stream Closed");
        }
        if (len == 0) {
            return 0;
        }
        while (slack == null) {
            char[] buf = new char[len]; // might read too much
            int n = in.read(buf);
            if (n == -1) {
                return -1;
            }
            if (n > 0) {
                slack = new String(buf, 0, n).getBytes(encoding);
                begin = 0;
            }
        }

        if (len > slack.length - begin) {
            len = slack.length - begin;
        }

        System.arraycopy(slack, begin, b, off, len);

        if ((begin += len) >= slack.length) {
            slack = null;
        }

        return len;
    }

    /**
     * Marks the read limit of the StringReader.
     *
     * @param limit the maximum limit of bytes that can be read before the
     *              mark position becomes invalid
     */
    public synchronized void mark(final int limit) {
        try {
            in.mark(limit);
        } catch (IOException ioe) {
            throw new RuntimeException(ioe.getMessage());
        }
    }


    /**
     * @return   the current number of bytes ready for reading
     * @exception IOException if an error occurs
     */
    public synchronized int available() throws IOException {
        if (in == null) {
            throw new IOException("Stream Closed");
        }
        if (slack != null) {
            return slack.length - begin;
        }
        if (in.ready()) {
            return 1;
        } else {
            return 0;
        }
    }

    /**
     * @return false - mark is not supported
     */
    public boolean markSupported () {
        return false;   // would be imprecise
    }

    /**
     * Resets the StringReader.
     *
     * @exception IOException if the StringReader fails to be reset
     */
    public synchronized void reset() throws IOException {
        if (in == null) {
            throw new IOException("Stream Closed");
        }
        slack = null;
        in.reset();
    }

    /**
     * Closes the Stringreader.
     *
     * @exception IOException if the original StringReader fails to be closed
     */
    public synchronized void close() throws IOException {
        if (in != null) {
            in.close();
            slack = null;
            in = null;
        }
    }
}