JS/JSP中文参数乱码

==========a标签参数乱码

 
String a = "";
try {
    a = new String(username.getBytes("ISO-8859-1"),"utf-8");
} catch (UnsupportedEncodingException e) {
    e.printStackTrace();
}

==========js异步方法参数乱码
// 两次转码
URLEncoder.encode("编码的是这里","GB2312")
// 两次解码
URLDecoder.decode(str,"GB2312")