ConnectionImpl.java

package com.github.HarryHook.coding2017.download.impl;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;

import com.github.HarryHook.coding2017.download.api.Connection;

public class ConnectionImpl implements Connection {

    private String url;

    public ConnectionImpl(String url) {

	this.url = url;
    }

    @Override
    public byte[] read(int startPos, int endPos) throws IOException {

	URL url = new URL(this.url);
	HttpURLConnection conn = (HttpURLConnection) url.openConnection();
	// conn.setRequestMethod("GET");
	// 设置500毫秒为超时值
	// conn.setReadTimeout(5000);
	conn.setRequestProperty("Range", "bytes=" + startPos + "-" + endPos);
	BufferedInputStream in = new BufferedInputStream(conn.getInputStream());
	ByteArrayOutputStream out = new ByteArrayOutputStream(1024);

	byte[] buffer = new byte[1024];
	int size = 0;
	while ((size = in.read(buffer)) != -1) {
	    out.write(buffer, 0, size);
	}
	byte[] b = out.toByteArray();
	out.close();
	in.close();

	return b;
    }

    @Override
    public int getContentLength() {

	try {
	    URL url1 = new URL(url);
	    HttpURLConnection conn = (HttpURLConnection) url1.openConnection();
	    return conn.getContentLength();

	} catch (Exception e) {

	    e.printStackTrace();
	}

	return -1;
    }

    @Override
    public void close() {

    }

}