com.github.antelopeframework.web.EscapedXmlUtil Maven / Gradle / Ivy

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package com.github.antelopeframework.web;

import java.io.IOException;

import javax.servlet.jsp.JspWriter;

/**
 * {@link org.apache.taglibs.standard.tag.common.core.Util}
 * @author yangzhi
 *
 */
public class EscapedXmlUtil {
	public static final int HIGHEST_SPECIAL = '>';
    public static char[][] specialCharactersRepresentation = new char[HIGHEST_SPECIAL + 1][];
    static {
        specialCharactersRepresentation['&'] = "&".toCharArray();
        specialCharactersRepresentation['<'] = "<".toCharArray();
        specialCharactersRepresentation['>'] = ">".toCharArray();
        specialCharactersRepresentation['"'] = """.toCharArray();
        specialCharactersRepresentation['\''] = "'".toCharArray();
    }
    
    /**
     * 
     * @param buffer
     * @return
     */
    public static String escapeXml(String buffer) {
    	if (buffer == null) {
    		return null;
    	}
    	
        int start = 0;
        int length = buffer.length();
        char[] arrayBuffer = buffer.toCharArray();
        StringBuffer escapedBuffer = null;

        for (int i = 0; i < length; i++) {
            char c = arrayBuffer[i];
            if (c <= HIGHEST_SPECIAL) {
                char[] escaped = specialCharactersRepresentation[c];
                if (escaped != null) {
                    // create StringBuffer to hold escaped xml string
                    if (start == 0) {
                        escapedBuffer = new StringBuffer(length + 5);
                    }
                    // add unescaped portion
                    if (start < i) {
                        escapedBuffer.append(arrayBuffer,start,i-start);
                    }
                    start = i + 1;
                    // add escaped xml
                    escapedBuffer.append(escaped);
                }
            }
        }
        // no xml escaping was necessary
        if (start == 0) {
            return buffer;
        }
        // add rest of unescaped portion
        if (start < length) {
            escapedBuffer.append(arrayBuffer,start,length-start);
        }
        return escapedBuffer.toString();
    }
    
    /**
     * 
     * @param buffer
     * @param length
     * @param w
     * @throws IOException
     */
	public static void write(char[] buffer, int length, JspWriter w) throws IOException {
		int start = 0;

		for (int i = 0; i < length; i++) {
			char c = buffer[i];
			if (c <= HIGHEST_SPECIAL) {
				char[] escaped = specialCharactersRepresentation[c];
				if (escaped != null) {
					// add unescaped portion
					if (start < i) {
						w.write(buffer, start, i - start);
					}
					// add escaped xml
					w.write(escaped);
					start = i + 1;
				}
			}
		}
		// add rest of unescaped portion
		if (start < length) {
			w.write(buffer, start, length - start);
		}
	}
	
}