java实现urlencode

https://www.cnblogs.com/del88/p/6496825.html

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    public static String urlEncode(String url) throws UnsupportedEncodingException {

        if(url == null) {

            return null;

        }

        final String reserved_char = ";/?:@=&";

        String ret = "";

        for(int i=0; i < url.length(); i++) {

            String cs = String.valueOf( url.charAt(i) );

            if(reserved_char.contains(cs)){

                ret += cs;

            }else{

                ret += URLEncoder.encode(cs, "utf-8");

            }

        }

        return ret.replace("+", "%20");

    }