package com.twelvemonkeys.io;
import com.twelvemonkeys.lang.Validate;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
/**
* An {@code InputStream} that reads bytes from a {@code String}.
*
* This class properly converts characters into bytes using a {@code Charset},
* unlike the deprecated {@link java.io.StringBufferInputStream}.
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
* @author last modified by $Author: haraldk$
* @version $Id: StringInputStream.java,v 1.0 03.09.13 10:19 haraldk Exp$
*/
public final class StringInputStream extends InputStream {
private final CharBuffer chars;
private final CharsetEncoder encoder;
private final ByteBuffer buffer;
public StringInputStream(final String string, final Charset charset) {
this(Validate.notNull(string, "string"), 0, string.length(), charset);
}
public StringInputStream(final String string, int offset, int length, final Charset charset) {
chars = CharBuffer.wrap(Validate.notNull(string, "string"), offset, offset + length);
encoder = Validate.notNull(charset, "charset").newEncoder();
buffer = ByteBuffer.allocate(256);
buffer.flip();
}
private boolean fillBuffer() {
buffer.clear();
encoder.encode(chars, buffer, chars.hasRemaining()); // TODO: Do we have to care about the result?
buffer.flip();
return buffer.hasRemaining();
}
private boolean ensureBuffer() {
return buffer.hasRemaining() || (chars.hasRemaining() && fillBuffer());
}
@Override
public int read() throws IOException {
if (!ensureBuffer()) {
return -1;
}
return buffer.get() & 0xff;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if (!ensureBuffer()) {
return -1;
}
int count = Math.min(buffer.remaining(), len);
buffer.get(b, off, count);
return count;
}
@Override
public long skip(long len) throws IOException {
if (!ensureBuffer()) {
return -1;
}
int count = (int) Math.min(buffer.remaining(), len);
int position = buffer.position();
buffer.position(position + count);
return count;
}
@Override
public int available() throws IOException {
return buffer.remaining();
}
}