public class FontUtil {

    public static void main(String[] args) {
        System.out.println(chinaToUnicode("未登陸！"));
        System.out.println(decodeUnicode("\u672a\u767b\u9646\uff01"));
    }
    
     /** 
     * 把中文轉成Unicode碼 
     *  
     * @param str 
     * @return 
     */  
    public
 
 static String chinaToUnicode(String str) {  
        String result = "";  
        for (int i = 0; i < str.length(); i++) {  
            int chr1 = (char) str.charAt(i);  
            if (chr1 >= 19968 && chr1 <= 171941) {// 漢字範圍 \u4e00-\u9fa5 (中文)  
                result += "\\u" + Integer.toHexString(chr1);  
            } 
 
else {  
                result += str.charAt(i);  
            }  
        }  
        return result;  
    }  
  
    /** 
     * 判斷是否為中文字符 
     *  
     * @param c 
     * @return 
     */  
    public 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;  
    }  
    
    
    //Unicode轉中文  
    public static String decodeUnicode(final String unicode) {     
         StringBuffer string = new StringBuffer();  
         
         String[] hex = unicode.split("\\\\u");  
   
         for (int i = 0; i < hex.length; i++) {  
               
             try {  
                 // 漢字範圍 \u4e00-\u9fa5 (中文)  
                 if(hex[i].length()>=4){//取前四個，判斷是否是漢字  
                     String chinese = hex[i].substring(0, 4);  
                     try {  
                         int chr = Integer.parseInt(chinese, 16);  
                         boolean isChinese = isChinese((char) chr);  
                         //轉化成功，判斷是否在  漢字範圍內  
                         if (isChinese){//在漢字範圍內  
                             // 追加成string  
                             string.append((char) chr);  
                             //並且追加  後面的字符  
                             String behindString = hex[i].substring(4);  
                             string.append(behindString);  
                         }else {  
                             string.append(hex[i]);  
                         }  
                     } catch (NumberFormatException e1) {  
                         string.append(hex[i]);  
                     }  
                       
                 }else{  
                     string.append(hex[i]);  
                 }  
             } catch (NumberFormatException e) {  
                 string.append(hex[i]);  
             }  
         }  
   
         return string.toString();  
    }  
    
}

java 中文與unicode互轉