ConnectionImpl.java

package com.coderising.download.impl;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Arrays;

import com.coderising.download.api.Connection;
	
 class ConnectionImpl implements Connection{
	 static final int BUFFER_SIZE = 1024;
	 URL url;
	 ConnectionImpl(String theUrl) {
		try {
			url=new URL(theUrl);
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	@Override
	public byte[] read(int startPos, int endPos) throws IOException {
		HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
		//?????
		httpConn.setRequestProperty("Range", "bytes=" + startPos + "-"
                + endPos);
		InputStream is = httpConn.getInputStream();
		 byte[] buff = new byte[BUFFER_SIZE];
		 int totalLen = endPos - startPos + 1;
		 ByteArrayOutputStream baos = new ByteArrayOutputStream();    
		 while(baos.size()<totalLen){
			int len = is.read();
			if(len<0){
				break;
			}
			//????
			baos.write(buff,0, len);  
		 }
		 if(baos.size() > totalLen){
	        	byte[] data = baos.toByteArray();
	        	return Arrays.copyOf(data, totalLen);
	        }
		return baos.toByteArray();
	}

	@Override
	public int getContentLength() {
		URLConnection openConnection;
		try {
			openConnection = url.openConnection();
			return openConnection.getContentLength();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return 0;
	}

	@Override
	public void close() {
		
		
	}

}