java 检测字符串中文乱码

1.检测是否为乱码

public static boolean isMessyCode(String strName) {
        Pattern p = Pattern.compile("\\s*|\t*|\r*|\n*");
        Matcher m = p.matcher(strName);
        String after = m.replaceAll("");
        String temp = after.replaceAll("\\p{P}", "");
        char[] ch = temp.trim().toCharArray();
        float chLength = 0 ;
        float count = 0;
        for (int i = 0; i < ch.length; i++) {
            char c = ch[i];
            if (!Character.isLetterOrDigit(c)) {
                if (!isChinese(c)) {
                    count = count + 1;
                }
                chLength++;
            }
        }
        float result = count / chLength ;
        if (result > 0.4) {
            return true;
        } else {
            return false;
        }
    }

2.检查字符是否为中文

private static boolean isChinese(char c) {
        Character.UnicodeBlock ub = Character.UnicodeBlock.of(c);
        if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
                || ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
                || ub == Character.UnicodeBlock.GENERAL_PUNCTUATION
                || ub == Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION
                || ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS) {
            return true;
        }
        return false;
    }

3.中文转换编码

public static String toChinese(String msg){
        if(isMessyCode(msg)){
            try {
                return new String(msg.getBytes("ISO8859-1"), "UTF-8");
            } catch (Exception e) {
            }
        }
        return msg ;
    }

Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS ： 4E00-9FBF：CJK 统一表意符号
Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS ：F900-FAFF：CJK
兼容象形文字 Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A
：3400-4DBF：CJK 统一表意符号扩展 A

CJK的意思是“Chinese，Japanese，Korea”的简写 ，实际上就是指中日韩三国的象形文字的Unicode编码
Character.UnicodeBlock.GENERAL_PUNCTUATION ：2000-206F：常用标点
Character.UnicodeBlock.CJK_SYMBOLS_AND_PUNCTUATION ：3000-303F：CJK 符号和标点
Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS ：FF00-FFEF：半角及全角形式

Character.isLetter(c)：判断字符是否是字母

Character.isDigit(c)：判断字符是否是数字