Limit input for EditText with InputFilter

Posted on | In |

项目中经常遇到EditText需要限制输入的情况，虽然EditText本身inputType自带了很多类型，如果遇到需要自定义输入限制时可以使用InputFilter接口，

例如需要限制输入表情符号，可以这样：

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public static class EmojiFilter implements InputFilter {

    @Override
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest,
                               int dstart, int dend) {
        if (source.length() >= 2) {
            if (containsEmoji(source.toString())) {
                return "";
            }
        }
        return null;
    }
}

/**
 * 检测是否有emoji表情
 *
 * @param source
 * @return
 */
public static boolean containsEmoji(String source) {
    int len = source.length();
    for (int i = 0; i < len; i++) {
        char codePoint = source.charAt(i);
        if (!isEmojiCharacter(codePoint)) { //如果不能匹配,则该字符是Emoji表情
            return true;
        }
    }
    return false;
}

/**
 * 判断是否是Emoji
 *
 * @param codePoint 比较的单个字符
 * @return
 */
private static boolean isEmojiCharacter(char codePoint) {
    return (codePoint == 0x0) || (codePoint == 0x9) || (codePoint == 0xA) || (codePoint == 0xD) || ((codePoint >= 0x20) && (codePoint <= 0xD7FF)) || ((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) || ((codePoint >= 0x10000));
}

protected void addInputFilter(InputFilter filter) {
    if (filter == null) {
        throw new IllegalArgumentException();
    }
    InputFilter[] filters = getFilters();
    InputFilter[] detFilters = new InputFilter[(filters == null ? 0 : filters.length) + 1];
    if (filters != null) {
        System.arraycopy(filters, 0, detFilters, 0, filters.length);
    }
    detFilters[detFilters.length - 1] = filter;
    setFilters(detFilters);
}

然后使用addInputFilter添加到EditText中即可。

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