String.replaceAll 正則表達式特殊字符橫線-

需求，把以下字符替換成空格：

!#$%&()[]*+-@?{|}~¢£¤¥¦§©ª«¬­®¯°±²³µ¶¹º»¼«½¾¿×~‘’`_\\^þÞ¡¨!<>\'*˝´\"ſß÷ΓΔΘΛΞΠΣΦΨΩγδθΛΦЂЃЉЊЋЍЏБДЖЗИЙЛФЦШЧЩЪЫЬЭЮЯ‐–—―‘’‚「」„†‡…•‰‹›‽₂₁₀ⁿ⁾⁽⁼⁻⁺⁹⁸⁷⁶⁵⁴⁰⁄₃₄₅₆₇₈₉₊₋₌₎₍€℅ℓ№℗⅟⅞⅝⅜⅛⅚⅙⅘⅗⅖⅕⅔⅓℮Ω™℠←↑→↓↔↕↖↗↘↙∂∆∏∑−∙√fflffiflfiff◊≥≤≠≈∫∞ѲҐΏГПѝѢ

天然考慮使用String的replaceAll來替換，jdk中此方法的定義以下：

/**
     * Replaces each substring of this string that matches the given <a
     * href="../util/regex/Pattern.html#sum">regular expression</a> with the
     * given replacement.
     *
     * <p> An invocation of this method of the form
     * <i>str</i>{@code .replaceAll(}<i>regex</i>{@code ,} <i>repl</i>{@code )}
     * yields exactly the same result as the expression
     *
     * <blockquote>
     * <code>
     * {@link java.util.regex.Pattern}.{@link
     * java.util.regex.Pattern#compile compile}(<i>regex</i>).{@link
     * java.util.regex.Pattern#matcher(java.lang.CharSequence) matcher}(<i>str</i>).{@link
     * java.util.regex.Matcher#replaceAll replaceAll}(<i>repl</i>)
     * </code>
     * </blockquote>
     *
     *<p>
     * Note that backslashes ({@code \}) and dollar signs ({@code $}) in the
     * replacement string may cause the results to be different than if it were
     * being treated as a literal replacement string; see
     * {@link java.util.regex.Matcher#replaceAll Matcher.replaceAll}.
     * Use {@link java.util.regex.Matcher#quoteReplacement} to suppress the special
     * meaning of these characters, if desired.
     *
     * @param   regex
     *          the regular expression to which this string is to be matched
     * @param   replacement
     *          the string to be substituted for each match
     *
     * @return  The resulting {@code String}
     *
     * @throws  PatternSyntaxException
     *          if the regular expression's syntax is invalid
     *
     * @see java.util.regex.Pattern
     *
     * @since 1.4
     * @spec JSR-51
     */
    public String replaceAll(String regex, String replacement) {
        return Pattern.compile(regex).matcher(this).replaceAll(replacement);
    }

第一個參數是正則表達式，把須要替換的字符放到[]中，而後放入第一個參數，這還沒完，須要把這些字符中的屬於正則表達式的特殊字符轉義一下。

特殊字符可見以下連接：連接

把特殊字符抽取出來，單獨替換，代碼以下：

result = result.replaceAll("[\\$\\(\\)\\*\\+\\.\\[\\]\\?\\\\^\\{\\}\\|]", " ");
        result = result.replaceAll("[!#%&-@~¢£¤¥¦§©ª«¬\u00AD®¯°±²³µ¶¹º»¼«½¾¿×~‘’`_þÞ¡¨!<>'˝´\"ſß÷ΓΔΘΛΞΠΣΦΨΩγδθΛΦЂЃЉЊЋЍЏБДЖЗИЙЛФЦШЧЩЪЫЬЭЮЯ‐–—―‘’‚「」„†‡…•‰‹›‽₂₁₀ⁿ⁾⁽⁼⁻⁺⁹⁸⁷⁶⁵⁴⁰⁄₃₄₅₆₇₈₉₊₋₌₎₍€℅ℓ№℗⅟⅞⅝⅜⅛⅚⅙⅘⅗⅖⅕⅔⅓℮Ω™℠←↑→↓↔↕↖↗↘↙∂∆∏∑−∙√fflffiflfiff◊≥≤≠≈∫∞ѲҐΏГПѝѢ]", " ");

寫完了以後測試發現數字也能夠被替換掉，這就奇怪了，使用二分法來篩選究竟是哪塊除了問題，最後定位到&-@，原來橫線也是特殊字符，只要ASCII碼在&（38）和@（64）之間的（好比數字、括號、星號、加號）都會知足正則表達式。把它也抽取出來轉義就行了，以下：

result = result.replaceAll("[\\$\\(\\)\\*\\+\\.\\[\\]\\?\\\\^\\{\\}\\|\\-]", " ");
        result = result.replaceAll("[!#%&@~¢£¤¥¦§©ª«¬\u00AD®¯°±²³µ¶¹º»¼«½¾¿×~‘’`_þÞ¡¨!<>'˝´\"ſß÷ΓΔΘΛΞΠΣΦΨΩγδθΛΦЂЃЉЊЋЍЏБДЖЗИЙЛФЦШЧЩЪЫЬЭЮЯ‐–—―‘’‚「」„†‡…•‰‹›‽₂₁₀ⁿ⁾⁽⁼⁻⁺⁹⁸⁷⁶⁵⁴⁰⁄₃₄₅₆₇₈₉₊₋₌₎₍€℅ℓ№℗⅟⅞⅝⅜⅛⅚⅙⅘⅗⅖⅕⅔⅓℮Ω™℠←↑→↓↔↕↖↗↘↙∂∆∏∑−∙√fflffiflfiff◊≥≤≠≈∫∞ѲҐΏГПѝѢ]", " ");