Go语言如何实现PHP的字典排序和签名生成？

$params = [
    'y' => 1,
    'x' => '有中文有符!@ 2号空格http://aaa.com',
    'a' => '{"a1":222,"a2":"u4e2du6587"}',
];
$signkey = 'abc';
ksort($params);
$encodedparams = http_build_query($params);
echo md5($encodedparams . $signkey);  //输出  18cebcb0d00d0c48904fd4b06ed0319d

import hashlib, urllib.parse
def sort_by_key(dict_var):
    sorted_tuple = sorted(dict_var.items(), key = lambda x:x[0])
    sorted_dict = {}
    for tuple_item in sorted_tuple:
        sorted_dict[tuple_item[0]] = tuple_item[1]
    return sorted_dict

sign_key = 'abc'
params = {
    'y': 1,
    'x': '有中文有符!@ 2号空格http://aaa.com',
    'a': '{"a1":222,"a2":"u4e2du6587"}',
}
params = sort_by_key(params)

md5 = hashlib.md5()
sign_str = '%s%s' % (urllib.parse.urlencode(params), sign_key)
md5.update(sign_str.encode('utf-8'))
sign = md5.hexdigest()
print(sign)  #输出 bb59a6422816bd2e9111ec3fb54e2106  ，跟上面不同主要是因为 a2 的值序列化跟php的不一样

package main

import (
    "crypto/md5"
    "encoding/hex"
    "fmt"
    "net/url"
    "sort"
)

func main() {
    params := map[string]string{
        "x": "有中文有符!@ 2号空格http://aaa.com",
        "y": "1",
        "a": "{"a1":222,"a2":"\u4e2d\u6587"}",
    }

    keys := make([]string, 0, len(params))
    for k := range params {
        keys = append(keys, k)
    }
    sort.Strings(keys)

    data := url.Values{}
    for _, k := range keys {
        data.Add(k, params[k])
    }

    encodedParams := data.Encode()
    signKey := "abc"
    signData := encodedParams + signKey
    hash := md5.New()
    hash.Write([]byte(signData))
    bytes := hash.Sum(nil)
    sign := hex.EncodeToString(bytes)

    fmt.Println(sign) //输出 18cebcb0d00d0c48904fd4b06ed0319d
}