x_tar.java

exploring Java 2ed edition 附带的例子程序

package exploringjava.contenthandlers.application;

import java.net.*;
import java.io.*;
import java.util.Date;

public class x_tar extends ContentHandler {
	static int 
		RECORDLEN = 512, 
		NAMEOFF = 0, NAMELEN = 100,
		SIZEOFF = 124, SIZELEN = 12,
		MTIMEOFF = 136, MTIMELEN = 12;

	public Object getContent(URLConnection uc) throws IOException {
		InputStream is = uc.getInputStream();
		StringBuffer output = new StringBuffer( "Tape Archive Listing:\n\n" );
		byte [] header = new byte[RECORDLEN];
		int count = 0;

		while ( (is.read(header) == RECORDLEN) && (header[NAMEOFF] != 0) ) {

			String name = new String(header, NAMEOFF, NAMELEN, "8859_1").trim();
			String s = new String(header, SIZEOFF, SIZELEN, "8859_1").trim();
			int size = Integer.parseInt(s, 8);
			s = new String(header, MTIMEOFF, MTIMELEN, "8859_1").trim();
			long l = Integer.parseInt(s, 8);
			Date mtime = new Date( l*1000 );

			output.append( size + " " + mtime + " " + name + "\n" );

			count += is.skip( size ) + RECORDLEN;
			if ( count % RECORDLEN != 0 )
				count += is.skip ( RECORDLEN - count % RECORDLEN);
		}

		if ( count == 0 )
			output.append("Not a valid TAR file\n");

		return( output.toString() );
	}
}