/** *//**
* author by http://www.bt285.cn http://www.5a520.cn
*/
package instream;   
  
import java.io.IOException;   
import java.io.InputStream;   
import java.net.HttpURLConnection;   
import java.net.URL;   
  
public final class HttpReader {   
    public static final int MAX_RETRY = 10;   
    private static long content_length;   
    private URL url;   
    private HttpURLConnection httpConnection;   
    private InputStream in_stream;   
    private long cur_pos;           //用于决定seek方法中是否执行文件定位   
    private int connect_timeout;   
    private int read_timeout;   
       
    public HttpReader(URL u) {   
        this(u, 5000, 5000);   
    }   
       
    public HttpReader(URL u, int connect_timeout, int read_timeout) {   
        this.connect_timeout = connect_timeout;   
        this.read_timeout = read_timeout;   
        url = u;   
        if (content_length == 0) {   
            int retry = 0;   
            while (retry < HttpReader.MAX_RETRY)   
                try {   
                    this.seek(0);   
                    content_length = httpConnection.getContentLength();   
                    break;   
                } catch (Exception e) {   
                    retry++;   
                }   
        }   
    }   
       
    public static long getContentLength() {   
        return content_length;   
    }   
       
    public int read(byte[] b, int off, int len) throws IOException {   
        int r = in_stream.read(b, off, len);   
        cur_pos += r;   
        return r;   
    }   
       
    public int getData(byte[] b, int off, int len) throws IOException {   
        int r, rema = len;   
        while (rema > 0) {   
            if ((r = in_stream.read(b, off, rema)) == -1) {   
                return -1;   
            }   
            rema -= r;   
            off += r;   
            cur_pos += r;   
        }   
        return len;   
    }   
       
    public void close() {   
        if (httpConnection != null) {   
            httpConnection.disconnect();   
            httpConnection = null;   
        }   
        if (in_stream != null) {   
            try {   
                in_stream.close();   
            } catch (IOException e) {}   
            in_stream = null;   
        }   
        url = null;   
    }   
       
    /**//*  
     * 抛出异常通知再试  
     * 响应码503可能是由某种暂时的原因引起的,例如同一IP频繁的连接请求可能遭服务器拒绝  
     */  
    public void seek(long start_pos) throws IOException {   
        if (start_pos == cur_pos && in_stream != null)   
            return;   
        if (httpConnection != null) {   
            httpConnection.disconnect();   
            httpConnection = null;   
        }   
        if (in_stream != null) {   
            in_stream.close();   
            in_stream = null;   
        }   
        httpConnection = (HttpURLConnection) url.openConnection();   
        httpConnection.setConnectTimeout(connect_timeout);   
        httpConnection.setReadTimeout(read_timeout);   
        String sProperty = "bytes=" + start_pos + "-";   
        httpConnection.setRequestProperty("Range", sProperty);   
        //httpConnection.setRequestProperty("Connection", "Keep-Alive");   
        int responseCode = httpConnection.getResponseCode();   
        if (responseCode < 200 || responseCode >= 300) {   
            try {   
                Thread.sleep(500);   
            } catch (InterruptedException e) {   
                e.printStackTrace();   
            }   
            throw new IOException("HTTP responseCode="+responseCode);   
        }   
  
        in_stream = httpConnection.getInputStream();   
        cur_pos = start_pos;   
    }   
  
}

package instream;   
  
public interface IWriterCallBack {   
    public boolean tryWriting(Writer w) throws InterruptedException;   
    public void updateBuffer(int i, int len);   
    public void updateWriterCount();   
    public void terminateWriters();   
}