edu.lternet.pasta.common.HTMLUtility.java Source code

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Here is the source code for edu.lternet.pasta.common.HTMLUtility.java

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/*
 * Copyright 2011-2013 the University of New Mexico.
 *
 * This work was supported by National Science Foundation Cooperative
 * Agreements #DEB-0832652 and #DEB-0936498.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 */

package edu.lternet.pasta.common;

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.IOException;

public class HTMLUtility {

    /**
      * Detects whether a string contains non-valid HTML control characters.
      *
      * @param in The String we want to check for invalid HTML characters.
      * @return true if one or more invalid characters were found, else false
      */
    public static boolean hasNonValidHTMLCharacter(String in) {
        boolean hasInvalid = false;
        char current; // current character

        if (in == null || ("".equals(in)))
            return false; // vacancy test

        for (int i = 0; i < in.length(); i++) {
            current = in.charAt(i);

            if (isInvalidHTMLCharacter(current)) {
                hasInvalid = true;
                break;
            }
        }

        return hasInvalid;
    }

    /**
     * This method helps to ensure that the output String has only valid HTML
     * characters by stripping out invalid control characters.
     *
     * @param in The String whose non-valid characters we want to remove.
     * @return The input String, stripped of non-valid characters.
     */
    public static String stripNonValidHTMLCharacters(String in) {

        char[] charBuf = null;

        if (in != null && !in.isEmpty()) {

            charBuf = in.toCharArray();
            int charBufSize = charBuf.length;

            for (int i = 0; i < charBufSize; i++) {

                if (isInvalidHTMLCharacter(charBuf[i])) {
                    charBuf[i] = '\uFFFD'; // Replace illegal character with replacement character
                }

            }

        }

        return new String(charBuf);

    }

    /*
      * Looks at a character to determine whether it's invalid for HTML.
      */
    private static boolean isInvalidHTMLCharacter(char c) {
        boolean invalid = false;

        // C0 control characters
        if ((int) c >= 0 && (int) c <= 31) {
            // Allowed characters tab (9), linefeed (10), and carriage return (13)
            if ((int) c != 9 && (int) c != 10 && (int) c != 13) {
                invalid = true;
            }
        }

        // DEL character
        else if ((int) c == 127) {
            invalid = true;
        }

        // C1 control characters
        else if ((int) c >= 128 && (int) c <= 159) {
            invalid = true;
        }

        // UTF-16 surrogate halves
        else if ((int) c >= 55296 && (int) c <= 57343) {
            invalid = true;
        }

        return invalid;
    }

    public static void main(String[] args) {

        File badIn = new File("/Users/servilla/tmp/bad.txt");
        File goodOut = new File("/Users/servilla/tmp/good.txt");

        String bad = null;

        try {
            bad = FileUtils.readFileToString(badIn, "UTF-8");
        } catch (IOException e) {
            System.err.println("HTMLUtility: " + e.getMessage());
            e.printStackTrace();
        }

        String good = stripNonValidHTMLCharacters(bad);

        try {
            FileUtils.writeStringToFile(goodOut, good, "UTF-8");
        } catch (IOException e) {
            System.err.println("HTMLUtility: " + e.getMessage());
            e.printStackTrace();
        }

    }

}