handler.java

exploring Java 2ed edition 附带的例子程序

package exploringjava.protocolhandlers.crypt;

import java.io.*;
import java.net.*;

public class Handler extends URLStreamHandler {

	protected void parseURL(URL url, String spec, int start, int limit) {
		int slash = spec.indexOf('/');
		String crypType = spec.substring(start, slash-1);
		super.parseURL(url, spec, slash, limit);
		setURL( url, "crypt:"+crypType, 
			url.getHost(), url.getPort(), url.getFile(), url.getRef() );
	}

	protected URLConnection openConnection(URL url) throws IOException {
		String crypType = url.getProtocol().substring(6);
		return new CryptURLConnection( url, crypType );
	}
}

class CryptURLConnection extends URLConnection {
	static int defaultPort = 80;
	CryptInputStream cis;

	public String getContentType() {
		return guessContentTypeFromName( url.getFile() );
	}

	CryptURLConnection ( URL url, String crypType ) throws IOException {
		super( url );
		try {
			String classname = "exploringjava.protocolhandlers.crypt." 
				+ crypType + "CryptInputStream";
			cis = (CryptInputStream)Class.forName(classname).newInstance();
		} catch ( Exception e ) { 
			throw new IOException("Crypt Class Not Found: "+e);
		}
	}

	public void connect() throws IOException { 
		int port = ( url.getPort() == -1 ) ? defaultPort : url.getPort();
		Socket s = new Socket( url.getHost(), port );

		// Send the filename in plaintext
		OutputStream server = s.getOutputStream();
		new PrintWriter( new OutputStreamWriter( server, "8859_1" ), true
			).println( "GET " + url.getFile() );

		// Initialize the CryptInputStream
		cis.set( s.getInputStream(), server );
		connected = true;
	}

	public InputStream getInputStream() throws IOException {
		if (!connected)
			connect();
		return ( cis );	
	}
}