Downloadutilse tool class without error

package cn.itcast.utils;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Base64;


public class DownLoadUtils {

    public static String getFileName(String agent, String filename) throws UnsupportedEncodingException {
        if (agent.contains("MSIE")) {
            // IE browser 
            filename = URLEncoder.encode(filename, "utf-8");
            filename = filename.replace("+", " ");
        } else if (agent.contains("Firefox")) {
            //  Firefox 
            Base64.Encoder encoder = Base64.getEncoder();
            filename = "=?utf-8?B?" +encoder.encodeToString(filename.getBytes("utf-8")) + "?=";
        } else {
            //  Other browsers 
            filename = URLEncoder.encode(filename, "utf-8");
        }
        return filename;
    }
}