Spring MVC的Post请求参数中文乱码的原因&处理

一、项目配置：

1. Spring 4.4.1-RELEASE
2. Jetty 9.3.5
3. JDK 1.8
4. Servlet 3.1.0
5. web.xml文件中没有配置编解码Filter

二、实际遇到的问题：
客户端(比如java)发送post请求访问接口，数据放在body里面，每个参数utf-8编码。
从body里面取出的中文参数是乱码。

---

下面是发送请求的代码和服务端接收请求的代码。

• 客户端代码。
  这是一个真实的第三方访问API的案例，这段代码请求到PHP系统正常，请求到java系统就会出现乱码。
  但是中文参数放到URL中解码正常，放到请求体中就是乱码。
  通过httpclient4.1发送Post请求如下：
  public static void postData(String sign, String timestamp) { // 创建默认的httpClient实例.
  CloseableHttpClient httpclient=null;
  String result="";
  try {
  httpclient = HttpClients.createDefault();
  String url = "http://example/api/entry";
  HttpPost httpPost = new HttpPost(url); //设置请求和传输超时时间
  RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(6000).setConnectTimeout(6000).build();
  httpPost.setConfig(requestConfig);
  MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
  entity.addPart("app_id", new StringBody("c5eb3ba8c0e7326559", Charset.forName("utf-8")));
  entity.addPart("method", new StringBody("kdt.item.add", Charset.forName("utf-8")));
  entity.addPart("timestamp", new StringBody(timestamp));
  entity.addPart("format", new StringBody("json", Charset.forName("utf-8")));
  entity.addPart("v", new StringBody("1.0", Charset.forName("utf-8")));
  entity.addPart("sign", new StringBody(sign, Charset.forName("utf-8")));
  entity.addPart("sign_method", new StringBody("md5", Charset.forName("utf-8")));
  entity.addPart("cid", new StringBody("5000000", Charset.forName("utf-8")));
  entity.addPart("tag_ids", new StringBody("0", Charset.forName("utf-8")));
  entity.addPart("price", new StringBody("0.01", Charset.forName("utf-8")));
  entity.addPart("title", new StringBody("测试", Charset.forName("utf-8")));
  entity.addPart("desc", new StringBody("test1", Charset.forName("utf-8"))); //是否是虚拟商品。0为否，1为是。目前不支持虚拟商品
  entity.addPart("is_virtual", new StringBody("0", Charset.forName("utf-8")));
  entity.addPart("post_fee", new StringBody("0.0", Charset.forName("utf-8"))); //Sku的属性串。格式：pText:vText;pText:vText，多个sku之间用逗号分隔，如：颜色:黄色;尺寸:M,颜色:黄色;尺寸:S。pText和vText文本中不可以存在冒号和分号以及逗号
  entity.addPart("sku_properties", new StringBody("color:white", Charset.forName("utf-8")));
  entity.addPart("sku_quantities", new StringBody("998,999", Charset.forName("utf-8")));
  entity.addPart("sku_prices", new StringBody("0.01,0.02", Charset.forName("utf-8")));
  entity.addPart("sku_outer_ids", new StringBody("null,null", Charset.forName("utf-8"))); //该商品的外部购买地址。当用户购买环境不支持微信或微博支付时会跳转到此地址
  entity.addPart("buy_url", new StringBody("http://img.cdn.sb.hongware.com/1461836641703511.gif", Charset.forName("utf-8")));
  entity.addPart("quantity", new StringBody("1998", Charset.forName("utf-8"))); //宝贝修改的时候需要这个参数
  httpPost.setEntity(entity);
  CloseableHttpResponse response = httpclient.execute(httpPost);
  try {
  HttpEntity httpEntity = response.getEntity();
  System.out.println(httpEntity.getContent());
  InputStream content = httpEntity.getContent();
  BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(content));
  String line;
  while ( (line=bufferedReader.readLine()) != null) {
  System.out.println(line);
  }
  } catch (Exception e) {
  e.printStackTrace();
  } finally {
  response.close();
  }
  } catch (Exception e) {
  e.printStackTrace();
  } finally {
  try {
  httpclient.close();
  } catch (Exception e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
  }
  }
  }

• 服务端代码如下
  为了简化演示，我把参数提取代码Map parameterMap = request.getParameterMap()冗余在这个入口函数中，以便说明问题：
  @RequestMapping(value = "/api/entry", produces = "application/json;charset=utf-8")
  public DeferredResult