UrlRetriever.java Accepts an URL from the command line, parses the host, port, and URI components from the URL and then retrieves the document. Requires the following classes:
import java.util.*;
/** This parses the input to get a host, port, and file, then
* passes these three values to the UriRetriever class to
* grab the URL from the Web.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class UrlRetriever {
public static void main(String[] args) {
checkUsage(args);
StringTokenizer tok = new StringTokenizer(args[0]);
String protocol = tok.nextToken(":");
checkProtocol(protocol);
String host = tok.nextToken(":/");
String uri;
int port = 80;
try {
uri = tok.nextToken("");
if (uri.charAt(0) == ':') {
tok = new StringTokenizer(uri);
port = Integer.parseInt(tok.nextToken(":/"));
uri = tok.nextToken("");
}
} catch(NoSuchElementException nsee) {
uri = "/";
}
UriRetriever uriClient = new UriRetriever(host, port, uri);
uriClient.connect();
}
/** Warn user if the URL was forgotten. */
private static void checkUsage(String[] args) {
if (args.length != 1) {
System.out.println("Usage: UrlRetriever ");
System.exit(-1);
}
}
/** Tell user that this can only handle HTTP. */
private static void checkProtocol(String protocol) {
if (!protocol.equals("http")) {
System.out.println("Don't understand protocol " + protocol);
System.exit(-1);
}
}
}
UriRetriever.java Given a host, port, and URI, retrieves the document from the HTTP server.
import java.net.*;
import java.io.*;
/** Retrieve a URL given the host, port, and file as three
* separate command-line arguments. A later class
* (UrlRetriever) supports a single URL instead.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class UriRetriever extends NetworkClient {
private String uri;
public static void main(String[] args) {
UriRetriever uriClient
= new UriRetriever(args[0], Integer.parseInt(args[1]),
args[2]);
uriClient.connect();
}
public UriRetriever(String host, int port, String uri) {
super(host, port);
this.uri = uri;
}
/** Send one GET line, then read the results one line at a
* time, printing each to standard output.
*/
// It is safe to use blocking IO (readLine), since
// HTTP servers close connection when done, resulting
// in a null value for readLine.
protected void handleConnection(Socket uriSocket)
throws IOException {
PrintWriter out = SocketUtil.getWriter(uriSocket);
BufferedReader in = SocketUtil.getReader(uriSocket);
out.println("GET " + uri + " HTTP/1.0rn");
String line;
while ((line = in.readLine()) != null) {
System.out.println("> " + line);
}
}
}
NetworkClient.java
import java.net.*;
import java.io.*;
/** A starting point for network clients. You'll need to
* override handleConnection, but in many cases connect can
* remain unchanged. It uses SocketUtil to simplify the
* creation of the PrintWriter and BufferedReader.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class NetworkClient {
protected String host;
protected int port;
/** Register host and port. The connection won't
* actually be established until you call
* connect.
*/
public NetworkClient(String host, int port) {
this.host = host;
this.port = port;
}
/** Establishes the connection, then passes the socket
* to handleConnection.
*/
public void connect() {
try {
Socket client = new Socket(host, port);
handleConnection(client);
} catch(UnknownHostException uhe) {
System.out.println("Unknown host: " + host);
uhe.printStackTrace();
} catch(IOException ioe) {
System.out.println("IOException: " + ioe);
ioe.printStackTrace();
}
}
/** This is the method you will override when
* making a network client for your task.
* The default version sends a single line
* ("Generic Network Client") to the server,
* reads one line of response, prints it, then exits.
*/
protected void handleConnection(Socket client)
throws IOException {
PrintWriter out = SocketUtil.getWriter(client);
BufferedReader in = SocketUtil.getReader(client);
out.println("Generic Network Client");
System.out.println
("Generic Network Client:n" +
"Made connection to " + host +
" and got '" + in.readLine() + "' in response");
client.close();
}
/** The hostname of the server we're contacting. */
public String getHost() {
return(host);
}
/** The port connection will be made on. */
public int getPort() {
return(port);
}
}
SocketUtil.java Provides utilities for wrapping a BufferedReader and PrintWriter around the Socket's input and output streams, respectively.
import java.net.*;
import java.io.*;
/** A shorthand way to create BufferedReaders and
* PrintWriters associated with a Socket.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* .
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public class SocketUtil {
/** Make a BufferedReader to get incoming data. */
public static BufferedReader getReader(Socket s)
throws IOException {
return(new BufferedReader(
new InputStreamReader(s.getInputStream())));
}
/** Make a PrintWriter to send outgoing data.
* This PrintWriter will automatically flush stream
* when println is called.
*/
public static PrintWriter getWriter(Socket s)
throws IOException {
// Second argument of true means autoflush.
return(new PrintWriter(s.getOutputStream(), true));
}
}
Note: Brought from our old site: http://www.salearningschool.com/example_codes/ on Jan 2nd, 2017 From: http://sitestree.com/?p=10231
Categories:Programming Code Examples, Java/J2EE/J2ME, Network Programming
Tags:Java/J2EE/J2MENetwork Programming
Post Data:2017-01-02 16:04:28
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