Javadoubts

Java HttpServletrRequest

Java HttpServletRequest interface extends the ServletRequest interface.

HttpServletRequest breaks the complete request in below part:

• Request URI
• Parameters
• Attributes
• ServletInputStream

requestURI

The requestURI comes out of request URL as shown below:

For example:

Below is the sample HTTP servlet URL

http://localhost:8080/Myproject/address/info/top.html?studentId=1

In HTTP servlet we get parse below info from Java HttpServletRequest

String uri = request.getRequestURI();
String contextPath = request.getContextPath();
String servletPath = request.getServletPath();
String pathInfo = request.getPathInfo();
String queryStr = request.getQueryString();

OUTPUT:

GetRequestURI → /Myproject/address/info/top.html

GetContextPath → /Myproject

GetServletPath → /address

GetPathInfo → /info/top.html

GetQueryString → info=intro

Parameter:

HttpsServletRequest provides methods to access request parameter (or query String).

Below are list of methods:

getParameter(String parameterName) → This method help us to get request parameter(or query string) value.

request.getParameter(“studentId”)

OUTPUT: 1

getParameterNames() → This method help us to get all request parameter(or query string) Names.

String[] paramNames = request.getParameterNames();

OUTPUT: [“studentId”]

getParameterValues() → This method help us to get all request parameter(or query string) values.

String[] paramValues = request.getParameterValues();

OUTPUT: [“1”]

getHeader() → The HttpServletRequest object also contains request headers as a key and value pairs. Request header contains information related to referrer, content type, content length, etc.

Below is the code snippet to collect header in Servlet class.

String contentType = request.getHeader(“Content-Type”);

OUTPUT: application/json

getSession() → This method returns the current session associated with the request.

getSession(true) →It will create brand new session if not session exist.

getSession(false) →This method will return null if no session exist.

Syntax:
HttpSession session = request.getSession();

session.setAttribute(“studentId”, request.getParameter(“studentId”));

InputStream

getInputStream() → HTTP POST request allows us to send huge data to server as part of request body. HTTP POST request data can be collect as part of InputStream as shown below:

Syntax:

 InputStream requestBodyInput = request.getInputStream();