zkoss/zk

/* PartialByteStream.java

    Purpose:
        
    Description:
        
    History:
        Tue Oct 23 12:03:38 CST 2018, Created by rudyhuang

Copyright (C) 2018 Potix Corporation. All Rights Reserved.
*/
package org.zkoss.web.servlet.http;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.servlet.http.HttpServletResponse;

/*package*/ class PartialByteStream extends ByteArrayOutputStream {
    private final int _from, _to;
    private int _ofs, _cnt;

    /*package*/ PartialByteStream(int from, int to) {
        super(4096);
        _from = from;
        _to = to;
    }

    /*package*/ void responseTo(HttpServletResponse response) throws IOException {
        //Note: after all content are written, _ofs is the total number
        //while _cnt the number of bytes being written.
        response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
        response.setContentLength(_cnt);

        int from = _from <= _ofs ? _from : _ofs - 1;
        int to = _to >= 0 && _to <= _ofs ? _to : _ofs - 1;
        response.setHeader("Content-Range", "bytes " + from + "-" + to + "/" + _ofs);

        writeTo(response.getOutputStream());
    }

    public synchronized void write(int b) {
        int ofs = _ofs++;
        if (ofs >= _from && (_to < 0 || ofs <= _to)) {
            ++_cnt;
            super.write(b);
        }
    }

    public synchronized void write(byte[] b, int ofs, int len) {
        while (--len >= 0)
            write(b[ofs++]);
    }
}