java encodeuri 中文

String string = attachmentURL;
Pattern p = Pattern.compile("[\u4e00-\u9fa5]+");


Matcher m = p.matcher(string);
StringBuffer b = new StringBuffer();
while (m.find()) {
    m.appendReplacement(b, URLEncoder.encode(m.group(0), "utf-8"));
}
m.appendTail(b);
System.out.println(b.toString());
String resultURL = b.toString();