从包装的HTTP请求中检索查询字符串参数和JSON主体(使用ServletRequestWrapper)

Question

将HTTP Post请求中的查询字符串和JSON正文发送到服务器是可能的，这是我已经理解的。为此，我们需要覆盖HttpServletRequest estWrapper类的getReader和getInputstream方法。我已经在本链接中进行了研究。在Stack Overflow中也看到了类似的答案。

所以现在我有一个登录操作，其中没有正文，只有post中的查询字符串params。当我试图读取它们时，getParameter()的输出为null。在我的包装器中，我打印了捕获的主体，它正确显示了从客户端机器接收到的正确数据。

读取查询字符串（获取参数（））和 JSON 正文 （gson.fromJson） 的琐碎方法，这些方法在从未包装的 HttpRequest 读取时使用，也可以在包装的 HTTP 请求上使用吗？我在这里错过了什么？

servlet的POST方法

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    System.out.println("from doPost");

    RequestWrapper wrappedrequest = new RequestWrapper(request);

    request = wrappedrequest;

    String action= request.getParameter("action");

    if(action.equals("update")) {
        Gson gson = new Gson();

        Order cart = gson.fromJson(request.getReader(), Order.class);
            CartDao dao= new CartDao(cart);

            dao.addData();

        }else if(action.equals("login")) {
            loginDao ld = new loginDao(request);
            int roleId = ld.authenticate();

            if(roleId!=-1) {

                System.out.println("Role ID Got is "+ roleId);
                HttpSession session = ld.loadSession(roleId);
                System.out.println("Init page for logging in user is = "+ session.getAttribute("initPage").toString());
                CartDao dao= new CartDao();
                JsonArray responseJson=  dao.getOrderList();

                request.setAttribute("ResponseJson", responseJson);

                RequestDispatcher rq = request.getRequestDispatcher(session.getAttribute("initPage").toString());
                rq.forward(request, response);


            }else {
                request.setAttribute("errmsg", "Invalid username/password");
                RequestDispatcher rq = request.getRequestDispatcher("login.jsp");
                rq.forward(request, response);
            }

        }else {

            System.out.println("No Action");
        }

}

请求包装器

public class RequestWrapper extends HttpServletRequestWrapper {

private String _body;

public RequestWrapper(HttpServletRequest request) throws IOException {
    super(request);
    _body = "";
    BufferedReader bufferedReader = request.getReader();           
    String line;
    while ((line = bufferedReader.readLine()) != null){
        _body += line; //when i print this it shows proper data got from client machine

    }
}

@Override
public ServletInputStream getInputStream() throws IOException {
    final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(_body.getBytes());
    return new ServletInputStream() {
        public int read() throws IOException {
            return byteArrayInputStream.read();
        }

        @Override
        public boolean isFinished() {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public boolean isReady() {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public void setReadListener(ReadListener arg0) {
            // TODO Auto-generated method stub

        }
    };
}

@Override
public BufferedReader getReader() throws IOException {
    return new BufferedReader(new InputStreamReader(this.getInputStream()));
}

Answer 1

最后我自己破解了这个。我所要做的就是读取查询字符串并将其保存在映射中，然后通过获取getParameter overriden方法中的键来返回值。主体通过读取输入流保存，并在调用重写的getReader时返回。这可以调用任意次数。：）虽然这很管用，但如果有人能详细解释一下为什么会管用，那就太好了。

具有魔力的星号代码如下所示，

public class RequestWrapper extends HttpServletRequestWrapper {



private String _body;
private String _queryString;

public RequestWrapper(HttpServletRequest request) throws IOException {
    super(request);
    _body = "";
    BufferedReader bufferedReader = request.getReader();           
    String line;
    while ((line = bufferedReader.readLine()) != null){
        _body += line;
    }

     _queryString = request.getQueryString();

     System.out.println(_body + _queryString);
}
}