utils.java

html过滤 html过滤 html过滤

/*  Copyright (c) 2006-2007, Vladimir Nikic
    All rights reserved.
	
    Redistribution and use of this software in source and binary forms, 
    with or without modification, are permitted provided that the following 
    conditions are met:
	
    * Redistributions of source code must retain the above
      copyright notice, this list of conditions and the
      following disclaimer.
	
    * 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.
	
    * The name of HtmlCleaner may not be used to endorse or promote 
      products derived from this software without specific prior
      written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
	
    You can contact Vladimir Nikic by sending e-mail to
    [e-mail]. Please include the word "HtmlCleaner" in the
    subject line.
*/

package org.htmlcleaner;

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

/**
 * <p>Common utilities.</p>
 *
 * Created by: Vladimir Nikic<br/>
 * Date: November, 2006.
 */
public class Utils {

    /**
     * Trims specified string from left.
     * @param s
     */
    public static String ltrim(String s) {
        if (s == null) {
            return null;
        }

        int index = 0;
        int len = s.length();

        while ( index < len && Character.isWhitespace(s.charAt(index)) ) {
            index++;
        }

        return (index >= len) ? "" : s.substring(index);
    }

    /**
     * Trims specified string from right.
     * @param s
     */
    public static String rtrim(String s) {
        if (s == null) {
            return null;
        }

        int len = s.length();
        int index = len;

        while ( index > 0 && Character.isWhitespace(s.charAt(index-1)) ) {
            index--;
        }

        return (index <= 0) ? "" : s.substring(0, index);
    }
    
    /**
     * Reads content from the specified URL with specified charset into string
     * @param url
     * @param charset
     * @throws IOException
     */
    public static StringBuffer readUrl(URL url, String charset) throws IOException {
        StringBuffer buffer = new StringBuffer(1024);

        Object content = url.getContent();
        if (content instanceof InputStream) {
            InputStreamReader reader = new InputStreamReader((InputStream)content, charset);
            char[] charArray = new char[1024];

            int charsRead = 0;
            do {
                charsRead = reader.read(charArray);
                if (charsRead >= 0) {
                    buffer.append(charArray, 0, charsRead);
                }
            } while (charsRead > 0);
        }

        return buffer;
    }

    public static boolean isHexadecimalDigit(char ch) {
        return Character.isDigit(ch) ||
               ch == 'A' || ch == 'a' || ch == 'B' || ch == 'b' || ch == 'C' || ch == 'c' ||
               ch == 'D' || ch == 'd' || ch == 'E' || ch == 'e' || ch == 'F' || ch == 'f';
    }
    
    /**
     * Escapes XML string.
     */
    public static String escapeXml(String s, boolean advanced, boolean recognizeUnicodeChars, boolean translateSpecialEntities) {
    	if (s != null) {
    		int len = s.length();
    		StringBuffer result = new StringBuffer(len);
    		
    		for (int i = 0; i < len; i++) {
    			char ch = s.charAt(i);
    			
    			if (ch == '&') {
    				if ( recognizeUnicodeChars && (i < len-1) && (s.charAt(i+1) == '#') ) {
    					int charIndex = i + 2;
    					String unicode = "";
    					while ( charIndex < len &&
                                (isHexadecimalDigit(s.charAt(charIndex)) || s.charAt(charIndex) == 'x' || s.charAt(charIndex) == 'X') 
                              ) {
    						unicode += s.charAt(charIndex);
    						charIndex++;
    					}
    					if (charIndex == len || !"".equals(unicode)) {
    						try {
    							char unicodeChar = unicode.toLowerCase().startsWith("x") ?
                                                        (char)Integer.parseInt(unicode.substring(1), 16) :                                
                                                        (char)Integer.parseInt(unicode);
    							if ( "&<>\'\"".indexOf(unicodeChar) < 0 ) {
	    							int replaceChunkSize = (charIndex < len && s.charAt(charIndex) == ';') ? unicode.length()+1 : unicode.length();
	    							result.append( String.valueOf(unicodeChar) );
	    							i += replaceChunkSize + 1;
    							} else {
        							i = charIndex;
        							result.append("&amp;#" + unicode + ";");
    							}
    						} catch (NumberFormatException e) {
    							i = charIndex;
    							result.append("&amp;#" + unicode + ";");
    						}
    					} else {
    						result.append("&amp;");
    					}
    				} else {
    					if (translateSpecialEntities) {
    						// get following sequence of most 10 characters
    						String seq = s.substring(i, i+Math.min(10, len-i));
    						int semiIndex = seq.indexOf(';');
    						if (semiIndex > 0) {
    							String entity = seq.substring(1, semiIndex);
    							Integer code = (Integer) SpecialEntities.entities.get(entity);
    							if (code != null) {
    								int entityLen = entity.length();
    								result.append( (char)code.intValue() );
    								i += entityLen + 1;
    								continue;
    							}
    						}
    					}
    					
    					if (advanced) {
                            String sub = s.substring(i);
                            if ( sub.startsWith("&amp;") ) {
                                result.append("&amp;");
                                i += 4;
                            } else if ( sub.startsWith("&apos;") ) {
                                result.append("&apos;");
                                i += 5;
                            } else if ( sub.startsWith("&gt;") ) {
                                result.append("&gt;");
                                i += 3;
                            } else if ( sub.startsWith("&lt;") ) {
                                result.append("&lt;");
                                i += 3;
                            } else if ( sub.startsWith("&quot;") ) {
                                result.append("&quot;");
                                i += 5;
                            } else {
                                result.append("&amp;");
                            }
    						
    						continue;
    					}
    					
    					result.append("&amp;");
    				}
    			} else if (ch == '\'') {
    				result.append("&apos;");
    			} else if (ch == '>') {
    				result.append("&gt;");
    			} else if (ch == '<') {
    				result.append("&lt;");
    			} else if (ch == '\"') {
    				result.append("&quot;");
    			} else {
    				result.append(ch);
    			}
    		}
    		
    		return result.toString();
    	}
    	
    	return null;
    }

}