解决HttpClient工具中application/x-www-form-urlencoded表单提交时，请求参数中文乱码问题

一、参数乱码现象

当我去请求第三方接口时，接口接收格式为Form表单的时候，使用HttpClient工具类。这时，对于封装进HttpPost对象里的请求参数,如果有中文参数，会出现乱码的现象。

二、代码现象复现

controller层

@RestController
@RequestMapping(value = "/http")
public class HttpClientController {

    @GetMapping(value = "/get")
    public PrePayResultVO getHttpClientDemo() {

        String url = "https://xxxx.xxxx.com/xxxx/Xxxxx";
        Map map = new HashMap<>();
        map.put("cardId", "1234567890");
        map.put("carNumber", "粤LX255Q");
        map.put("parkCode", "1234567890");
        map.put("startTime", "2018-09-18");
        map.put("endTime", "2018-10-18");
        map.put("defferMoney", "0.01");

        JSONObject jsonObject = HttpClientUtils.postForForm(url, map);
        PrePayResultVO prePayResultVO =JSONObject.parseObject(jsonObject.toString(), PrePayResultVO.class);
        return prePayResultVO;
    }
}

httpClientUtils

public static JSONObject postForForm(String url, Map<String, String> parms) {
        HttpPost httpPost = new HttpPost(url);
        ArrayList<BasicNameValuePair> list = new ArrayList<>();
        parms.forEach((key, value) -> list.add(new BasicNameValuePair(key, value)));
        CloseableHttpClient httpClient = HttpClients.createDefault();
        try {
            if (Objects.nonNull(parms) && parms.size() >0) {
                httpPost.setEntity(new UrlEncodedFormEntity(list, "UTF-8"));
            }
            InputStream content = httpPost.getEntity().getContent();
            InputStreamReader inputStreamReader = new InputStreamReader(content, "UTF-8");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String readLine = bufferedReader.readLine();
            System.out.println("readLine===================================" + readLine);
            HttpResponse response = httpClient.execute(httpPost);
            HttpEntity entity = response.getEntity();
            JSONObject jsonObject = JSON.parseObject(EntityUtils.toString(entity, "UTF-8"));
            return jsonObject;
        }catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (Objects.nonNull(httpClient)){
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }

打印结果

由此可见，本应打印中的请求参数 “粤LX255Q”，却变成了 “%E7%B2%A4LX255Q” 这种格式的字符串。

三、产生原因

在我们发起请求时，浏览器首先会将这些中文字符进行编码然后再发送给服务器。实际上，浏览器会将它们转换为 application/x-www-form-urlencoded MIME 字符串。

四、解决方法

 public static JSONObject postForForm(String url, Map<String, String> parms) {
        HttpPost httpPost = new HttpPost(url);
        ArrayList<BasicNameValuePair> list = new ArrayList<>();
        parms.forEach((key, value) -> list.add(new BasicNameValuePair(key, value)));
        CloseableHttpClient httpClient = HttpClients.createDefault();
        try {
            if (Objects.nonNull(parms) && parms.size() >0) {
                httpPost.setEntity(new UrlEncodedFormEntity(list, "UTF-8"));
            }
            InputStream content = httpPost.getEntity().getContent();
            InputStreamReader inputStreamReader = new InputStreamReader(content, "UTF-8");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String readLine = bufferedReader.readLine();
            String s = URLDecoder.decode(readLine, "UTF-8");
            System.out.println("readLine===================================" + readLine);
            System.out.println("s==========================================" + s);
            HttpResponse response = httpClient.execute(httpPost);
            HttpEntity entity = response.getEntity();
            JSONObject jsonObject = JSON.parseObject(EntityUtils.toString(entity, "UTF-8"));
            return jsonObject;
        }catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (Objects.nonNull(httpClient)){
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }

在获取请求参数时，再对其使用URLDecoder将application/x-www-form-rulencoded MIME字符串转换为对应编码的普通字符串。

打印结果

五、URLDecoder和URLEncoder的使用总结

• URLDecoder类包含一个decode(String s,String enc)静态方法，它可以将application/x-www-form-urlencoded MIME字符串转成普通字符串；

• URLEncoder类包含一个encode(String s,String enc)静态方法，它可以将普通字符串转换成application/x-www-form-urlencoded MIME字符串。

public static void main(String[] args) throws UnsupportedEncodingException {
        String name = "千夜";

        String decode = URLDecoder.decode("%E5%8D%83%E5%A4%9C", "UTF-8");
        System.out.println("application/x-www-form-urlencoded MIME字符串转成普通字符串===============" + decode);
        String encode = URLEncoder.encode(name, "UTF-8");
        System.out.println("普通字符串转换成application/x-www-form-urlencoded MIME字符串=============" +encode);
    }