try {
// Check the arguments
if (args.length != 2)
throw new IllegalArgumentException("Wrong number of args");
// Get an output stream to write the URL contents to
OutputStream to_file = new FileOutputStream(args[1]);
// Now use the URI class to parse the user-specified URL into
// its various parts. java.net.URI is new in Java 1.4; it is like
// URL, but has more powerful parsing, and does not have built-in
// networking capability.
URI uri = new URI(args[0]);
String protocol = uri.getScheme();
String host = uri.getHost();
int port = uri.getPort();
String path = uri.getRawPath();
if (path == null || path.length() == 0) path = "/";
String query = uri.getRawQuery();
if (query != null && query.length() > 0)
path += "?" + query;
Socket socket; // The socket we'll use to communicate
if (protocol.equals("http")) {
// This is a normal http protocol, create a normal socket
if (port == -1) port = 80; // Default http port
socket = new Socket(host, port);
}
else if (protocol.equals("https")) {
// For HTTPS we need to create a secure socket
if (port == -1) port = 443;
SocketFactory factory = SSLSocketFactory.getDefault();
SSLSocket ssock = (SSLSocket) factory.createSocket(host, port);
// Get the server's certificate
SSLSession session = ssock.getSession();
X509Certificate cert = null;
try {
cert = (X509Certificate)session.getPeerCertificates()[0];
}
catch(SSLPeerUnverifiedException e) {
// This means there was no certificate, or the certificate
// was not valid.
System.err.println(session.getPeerHost() +
" did not present a valid certificate");
System.exit(1);
}
// Print certificate details
System.out.println(session.getPeerHost() +
" has presented a certificate belonging to:\t" +
"[" + cert.getSubjectDN() + "]\n" +
"The certificate was issued by: \t" +
"[" + cert.getIssuerDN() + "]");
// We could ask the user here to confirm that they trust
// the certificate owner and issuer before proceeding...
socket = ssock;
}
else {
throw new IllegalArgumentException("URL must use http: or " +
"https: protocol");
}
/*
* We now have a regular socket or an SSL socket. HTTP and HTTPS
* are the same from here on.
*/
// Get input and output streams for the socket
InputStream from_server = socket.getInputStream();
PrintWriter to_server = new PrintWriter(socket.getOutputStream());
// Send the HTTP GET command to the Web server, specifying the file
// We specify HTTP 1.0 instead of 1.1 because we don't know how
// to handle Transfer-Encoding: chunked in the response
to_server.print("GET " + path + " HTTP/1.0\r\n" +
"Host: " + host + "\r\n" +
"Connection: close\r\n\r\n");
to_server.flush(); // Send it right now!
// Here is a buffer we use for reading from the server
byte[] buffer = new byte[8 * 1024];
int bytes_read;
// Now read the HTTP headers the server returns, and print these
// to the console. Read from the server until we've got at
// least 4K bytes or until we get EOF. Assume that we'll find
// the end of the headers somewhere in the first 4K bytes.
int numbytes = 0;
while(true) {
bytes_read = from_server.read(buffer, numbytes,
buffer.length-numbytes);
if (bytes_read == -1) break;
numbytes += bytes_read;
if (numbytes >= 4 * 1024) break;
}
// Loop through the bytes, looking for the \r\n\r\n pattern
// (13, 10, 13, 10) that marks the end of the headers
int i = 0;
while(i <= numbytes-4) {
if (buffer[i++] == 13 && buffer[i++] == 10 &&
buffer[i++] == 13 && buffer[i++] == 10) break;
}
// If we didn't find the end of the headers, abort
if (i > numbytes-4) {
throw new IOException("End of headers not found in first " +
numbytes + " bytes");
}
// Now convert the headers to a Latin-1 string (omitting the final
// blank line) and then print them out to the console
String headers = new String(buffer, 0, i-2, "ISO-8859-1");
System.out.print(headers);
// Any bytes we read after the headers get written to the file.
to_file.write(buffer, i, numbytes-i);
// Now read the rest of the bytes and write to the file
while((bytes_read = from_server.read(buffer)) != -1)
to_file.write(buffer, 0, bytes_read);
// When the server closes the connection, we close our stuff, too
socket.close();
to_file.close();
}
catch (Exception e) { // Report any errors that arise
System.err.println(e);
System.err.println("Usage: java HttpClient <URL> [<filename>]");
}
