URL openStream

OReilly.Java.I.O.2nd.Edition
5.1. URLs

		InputStream in = null;
		try {
			URL u = new URL("http://www.oreilly.com/");
			in = u.openStream();
			for (int c = in.read(); c != -1; c = in.read()) {
				System.out.write(c);
			}
		} catch (MalformedURLException ex) {

		} finally {
			if (in != null)
				in.close();
		}

Most [b]network[/b] connections, even on LANs, are [b]slower and less reliable[/b] sources of data than files. Connections across the Internet are even [b]slower and less reliable[/b], and connections through a modem are slower and less reliable still. [b]One way to enhance performance under these conditions is to buffer the data: to read as much data as you can into a temporary storage array inside the class[/b], then parcel it out as needed. In the next chapter, you'll learn about the [b]BufferedInputStream[/b] class that does exactly this.

Untrusted code running [b]under the control of a security manager[/b] e.g., [b]applets[/b] that run inside a web browser are normally allowed to connect [b]only to the host they were downloaded from[/b]. This host can be determined from the URL returned by the getCodeBase( ) method of the Applet class. Attempts to [b]connect to other hosts throw security exceptions[/b]. You can create URLs that point to other hosts, but you may not download data from them using openStream( ) or any other method. (This security restriction for applets applies to any network connection, regardless of how you get it.)


5.2. URL Connections

[b]URL connections are closely related to URLs[/b], as their name implies. Indeed, you get a reference to a URLConnection by using the openConnection( ) method of a URL object; in many ways, the URL class is only a wrapper around the URLConnection class. URL connections [b]provide more control over the communication between the client and the server[/b].