import java.util.regex.Matcher;

import java.util.regex.Pattern;   

/**

 * <p>

 * Title: HTML相关的正则表达式工具类

 * </p>

 * <p>

 * Description: 包括过滤HTML标记，转换HTML标记，替换特定HTML标记

 * </p>

 * <p>

 * Copyright: Copyright (c) 2006

 * </p>

 *

 * @author hejian

 * @version 1.0

 * @createtime 2006-10-16

 */  

public class HtmlRegexpUtil {

    private final static String regxpForHtml = "<([^>]*)>"; // 过滤所有以<开头以>结尾的标签   

    private final static String regxpForImgTag = "<\\s*img\\s+([^>]*)\\s*>"; // 找出IMG标签   

    private final static String regxpForImaTagSrcAttrib = "src=\"([^\"]+)\""; // 找出IMG标签的SRC属性   

    /**

     *

     */

    public HtmlRegexpUtil() {

        // TODO Auto-generated constructor stub

    }   

    /**

     *

     * 基本功能：替换标记以正常显示

     * <p>

     *

     * @param input

     * @return String

     */

    public String replaceTag(String input) {

        if (!hasSpecialChars(input)) {

            return input;

        }

        StringBuffer filtered = new StringBuffer(input.length());

        char c;

        for (int i = 0; i <= input.length() - 1; i++) {

            c = input.charAt(i);

            switch (c) {

            case '<':

                filtered.append("&lt;");

                break;

            case '>':

                filtered.append("&gt;");

                break;

            case '"':

                filtered.append("&quot;");

                break;

            case '&':

                filtered.append("&amp;");

                break;

            default:

                filtered.append(c);

            }   

        }

        return (filtered.toString());

    }   

    /**

     *

     * 基本功能：判断标记是否存在

     * <p>

     *

     * @param input

     * @return boolean

     */

    public boolean hasSpecialChars(String input) {

        boolean flag = false;

        if ((input != null) && (input.length() > 0)) {

            char c;

            for (int i = 0; i <= input.length() - 1; i++) {

                c = input.charAt(i);

                switch (c) {

                case '>':

                    flag = true;

                    break;

                case '<':

                    flag = true;

                    break;

                case '"':

                    flag = true;

                    break;

                case '&':

                    flag = true;

                    break;

                }

            }

        }

        return flag;

    }   

    /**

     *

     * 基本功能：过滤所有以"<"开头以">"结尾的标签

     * <p>

     *

     * @param str

     * @return String

     */

    public static String filterHtml(String str) {

        Pattern pattern = Pattern.compile(regxpForHtml);

        Matcher matcher = pattern.matcher(str);

        StringBuffer sb = new StringBuffer();

        boolean result1 = matcher.find();

        while (result1) {

            matcher.appendReplacement(sb, "");

            result1 = matcher.find();

        }

        matcher.appendTail(sb);

        return sb.toString();

    }   

    /**

     *

     * 基本功能：过滤指定标签

     * <p>

     *

     * @param str

     * @param tag

     *            指定标签

     * @return String

     */

    public static String fiterHtmlTag(String str, String tag) {

        String regxp = "<\\s*" + tag + "\\s+([^>]*)\\s*>";

        Pattern pattern = Pattern.compile(regxp);

        Matcher matcher = pattern.matcher(str);

        StringBuffer sb = new StringBuffer();

        boolean result1 = matcher.find();

        while (result1) {

            matcher.appendReplacement(sb, "");

            result1 = matcher.find();

        }

        matcher.appendTail(sb);

        return sb.toString();

    }   

    /**

     *

     * 基本功能：替换指定的标签

     * <p>

     *

     * @param str

     * @param beforeTag

     *            要替换的标签

     * @param tagAttrib

     *            要替换的标签属性值

     * @param startTag

     *            新标签开始标记

     * @param endTag

     *            新标签结束标记

     * @return String

     * @如：替换img标签的src属性值为[img]属性值[/img]

     */

    public static String replaceHtmlTag(String str, String beforeTag,

            String tagAttrib, String startTag, String endTag) {

        String regxpForTag = "<\\s*" + beforeTag + "\\s+([^>]*)\\s*>";

        String regxpForTagAttrib = tagAttrib + "=\"([^\"]+)\"";

        Pattern patternForTag = Pattern.compile(regxpForTag);

        Pattern patternForAttrib = Pattern.compile(regxpForTagAttrib);

        Matcher matcherForTag = patternForTag.matcher(str);

        StringBuffer sb = new StringBuffer();

        boolean result = matcherForTag.find();

        while (result) {

            StringBuffer sbreplace = new StringBuffer();

            Matcher matcherForAttrib = patternForAttrib.matcher(matcherForTag

                    .group(1));

            if (matcherForAttrib.find()) {

                matcherForAttrib.appendReplacement(sbreplace, startTag

                        + matcherForAttrib.group(1) + endTag);

            }

            matcherForTag.appendReplacement(sb, sbreplace.toString());

            result = matcherForTag.find();

        }

        matcherForTag.appendTail(sb);

        return sb.toString();

    }

}