实现和 jdk\bin\native2ascii.exe 同样的功能
public static String convert(String str){String tmp;StringBuffer sb = new StringBuffer();char c;for (int i = 0; i < str.length(); i++) {c = str.charAt(i);if(c > 255){sb.append("\\u");tmp = Integer.toHexString(c);if(tmp.length() == 3){sb.append("0");}sb.append(tmp);}else{sb.append(c);}}return sb.toString();}