Servlet获取AJAX POST请求中参数以form data和request payload形式传输的方法

RequestURL:http://127.0.0.1:8080/test/test.do?name=mikan&address=street
Request Method:GET
Status Code:200 OK
Request Headers
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding:gzip,deflate,sdch
Accept-Language:zh-CN,zh;q=0.8,en;q=0.6
AlexaToolbar-ALX_NS_PH:AlexaToolbar/alxg-3.2
Connection:keep-alive
Cookie:JSESSIONID=74AC93F9F572980B6FC10474CD8EDD8D
Host:127.0.0.1:8080
Referer:http://127.0.0.1:8080/test/index.jsp
User-Agent:Mozilla/5.0 (Windows NT 6.1)AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.149 Safari/537.36
Query String Parameters
name:mikan
address:street
Response Headers
Content-Length:2
Date:Sun, 11 May 2014 10:42:38 GMT
Server:Apache-Coyote/1.1

RequestURL:http://127.0.0.1:8080/test/test.do
Request Method:POST
Status Code:200 OK
Request Headers
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding:gzip,deflate,sdch
Accept-Language:zh-CN,zh;q=0.8,en;q=0.6
AlexaToolbar-ALX_NS_PH:AlexaToolbar/alxg-3.2
Cache-Control:max-age=0
Connection:keep-alive
Content-Length:25
Content-Type:application/x-www-form-urlencoded
Cookie:JSESSIONID=74AC93F9F572980B6FC10474CD8EDD8D
Host:127.0.0.1:8080
Origin:http://127.0.0.1:8080
Referer:http://127.0.0.1:8080/test/index.jsp
User-Agent:Mozilla/5.0 (Windows NT 6.1)AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.149 Safari/537.36
Form Data
name:mikan
address:street
Response Headers
Content-Length:2
Date:Sun, 11 May 2014 11:05:33 GMT
Server:Apache-Coyote/1.1

function getXMLHttpRequest() {
     var xhr;
     if(window.ActiveXObject) {
          xhr= new ActiveXObject("Microsoft.XMLHTTP");
     }else if (window.XMLHttpRequest) {
          xhr= new XMLHttpRequest();
     }else {
          xhr= null;
     }
     return xhr;
}
function save() {
     var xhr = getXMLHttpRequest();
     xhr.open("post","http://127.0.0.1:8080/test/test.do");
     var data = "name=mikan&address=street...";
     xhr.send(data);
     xhr.onreadystatechange= function() {
          if(xhr.readyState == 4 && xhr.status == 200) {
              alert("returned:"+ xhr.responseText);
          }
     };
}

RequestURL:http://127.0.0.1:8080/test/test.do
Request Method:POST
Status Code:200 OK
Request Headers
Accept:*/*
Accept-Encoding:gzip,deflate,sdch
Accept-Language:zh-CN,zh;q=0.8,en;q=0.6
AlexaToolbar-ALX_NS_PH:AlexaToolbar/alxg-3.2
Connection:keep-alive
Content-Length:28
Content-Type:text/plain;charset=UTF-8
Cookie:JSESSIONID=C40C7823648E952E7C6F7D2E687A0A89
Host:127.0.0.1:8080
Origin:http://127.0.0.1:8080
Referer:http://127.0.0.1:8080/test/index.jsp
User-Agent:Mozilla/5.0 (Windows NT 6.1)AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.149 Safari/537.36
Request Payload
name=mikan&address=street
Response Headers
Content-Length:2
Date:Sun, 11 May 2014 11:49:23 GMT
Server:Apache-Coyote/1.1

protectedvoid parseParameters() {
      //省略部分代码......
      parameters.handleQueryParameters();// 这里是处理url中的参数
      //省略部分代码......
      if ("multipart/form-data".equals(contentType)) { // 这里是处理文件上传请求
        parseParts();
        success = true;
        return;
      }
      if(!("application/x-www-form-urlencoded".equals(contentType))) {// 这里如果是非POST请求直接返回，不再进行处理
        success = true;
        return;
      }
      //下面的代码才是处理POST请求参数
      //省略部分代码......
      try {
        if (readPostBody(formData, len)!= len) { // 读取请求体数据
          return;
        }
      } catch (IOException e) {
        // Client disconnect
        if(context.getLogger().isDebugEnabled()) {
          context.getLogger().debug(
              sm.getString("coyoteRequest.parseParameters"),e);
        }
        return;
      }
      parameters.processParameters(formData, 0, len); // 处理POST请求参数，把它放到requestparameter map中（即request.getParameterMap获取到的Map，request.getParameter(name)也是从这个Map中获取的）
      // 省略部分代码......
}
protected int readPostBody(byte body[], int len)
    throws IOException {
    int offset = 0;
    do {
      int inputLen = getStream().read(body, offset, len - offset);
      if (inputLen <= 0) {
        return offset;
      }
      offset += inputLen;
    } while ((len - offset) > 0);
    return len;
}

privateString getRequestPayload(HttpServletRequest req) {
     StringBuildersb = new StringBuilder();
     try(BufferedReaderreader = req.getReader();) {
          char[]buff = new char[1024];
          intlen;
          while((len = reader.read(buff)) != -1) {
              sb.append(buff,0, len);
          }
     }catch (IOException e) {
          e.printStackTrace();
     }
     returnsb.toString();
}

xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");