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 com.coderising.download.api.Connection;
public class ConnectionImpl implements Connection{
private URL url;
private HttpURLConnection connection;
public ConnectionImpl(String url) {
try {
this.url = new URL(url);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private HttpURLConnection initConnection(){
HttpURLConnection con = null;
try {
con = (HttpURLConnection)url.openConnection();
con.setConnectTimeout(2000);
con.setRequestMethod("GET");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}
@Override
public byte[] read(int startPos, int endPos) throws IOException {
connection = initConnection();
connection.setRequestProperty("Range", "bytes=" + startPos + "-" + endPos); //nullPointException
InputStream input = connection.getInputStream();
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int i=0;
byte[] bt = new byte[1024];
while((i=input.read(bt))!=-1){
bos.write(bt,0,i);
}
return bos.toByteArray();
}
@Override
public int getContentLength() {
HttpURLConnection con = initConnection();
try {
if (con.getResponseCode() == 200){
//服务器返回内容的长度,本质就是文件的长度
return con.getContentLength();
}
} catch (IOException e) {
e.printStackTrace();
}
return 0;
}
@Override
public void close() {
this.connection=null;
}
}