newsdbarticle.java

java高级使用教程 全书一共分六章

// NewsDbArticle - netnews database article
//
// Copyright (C) 1996 by Jef Poskanzer <[e-mail]>.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme.Nnrpd;

import java.io.*;
import java.util.*;
import java.net.*;
import Acme.Utils;

/// Netnews database article.
// <P>
// This represents a news database article.
// <P>
// <A HREF="/resources/classes/Acme/Nnrpd/NewsDbArticle.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>

public class NewsDbArticle
    {

    private long dbStamp;
    private String text;
    private int headLen, bodyStart;	// these generally differ by only 1
    private Hashtable headers = new Hashtable();

    /// Constructor.
    // @exception NewsDbException if something goes wrong
    public NewsDbArticle( long dbStamp, String text ) throws NewsDbException
	{
	this.dbStamp = dbStamp;
	this.text = text;

	// Figure out headLen/bodyStart.
	int lflf = text.indexOf( "\n\n" );
	if ( lflf != -1 )
	    {
	    headLen = lflf + 1;
	    bodyStart = lflf + 2;
	    }
	else
	    throw new NewsDbException( "can't find end of header" );
	}

    /// Get the database stamp.
    // This is used internally when dealing with multiple news databases,
    // to make sure that an obect returned from one is not passed to another.
    protected long getDbStamp()
	{
	return dbStamp;
	}

    /// Get the article text.
    public String getText()
	{
	return text;
	}

    /// Get the length of the article header.
    public int getHeadLen()
	{
	return headLen;
	}

    /// Get the start position of the article body.
    public int getBodyStart()
	{
	return bodyStart;
	}

    /// Get a header field.
    public String getHeader( String name )
	{
	String val = (String) headers.get( name );
	if ( val == null )
	    {
	    val = getHeader( text, name );
	    if ( val == null )
		return null;
	    headers.put( name, val );
	    }
	return val;
	}

    /// Extract the named header from the text of a netnews article.
    // Does a case-insensitive search for "<BOL>name:"
    // Stops searching at the end of the headers.
    // Returns null if the header was not found.
    public static String getHeader( String text, String name )
	{
	boolean bol = true;
	int nameLen = name.length();
	int textLen = text.length();
	if ( name.charAt( nameLen - 1 ) != ':' )
	    {
	    name = name + ":";
	    ++nameLen;
	    }
	char[] nameChars = name.toLowerCase().toCharArray();
	char ch;
	int nameIdx = 0;
	for ( int textIdx = 0; textIdx < textLen; ++textIdx )
	    {
	    ch = Character.toLowerCase( text.charAt( textIdx ) );
	    if ( ch == '\n' )
		{
		if ( bol )
		    break;
		bol = true;
		nameIdx = 0;
		continue;
		}
	    if ( nameIdx == 0 && ! bol )
		continue;
	    bol = false;
	    if ( ch == nameChars[nameIdx] )
		{
		++nameIdx;
		if ( nameIdx >= nameLen )
		    {
		    // Found it.
		    ++textIdx;
		    int startIdx =
			textIdx + Utils.strSpan( text, " \t", textIdx );
		    int endIdx = text.indexOf( '\n', startIdx );
		    return text.substring( startIdx, endIdx );
		    }
		}
	    else
		nameIdx = 0;
	    }
	return null;
	}

    }