Request Implicit Object in JSP by R4R Team

Request Implicit Object in JSP with examples:
Here we will discuss request implicit object in JSP. It is mainly used to get the data on a JSP page which has been entered by user on the previous JSP page.

Methods of request Implicit Object:


getParameter(String name) - This method is used to get the value of a request’s parameter. For example at login page user enters user-id and password and once the credentials are verified the login page gets redirected to user information page, then using request.getParameter we can get the value of user-id and password which user has input at the login page.

String Uid= request.getParameter("user-id");

String Pass= request.getParameter("password");
getParameterNames() - It returns enumeration of all the parameter names associated to the request.

Enumeration e= request.getParameterNames();
getParameterValues(String name) – It returns the array of parameter values.

String[] allpasswords = request.getParameterValues("password");
getAttribute(String name) – Used to get the attribute value. request.getAttribute(“admin”) would give you the value of attribute admin.
getAttributeNames() – It is generally used to get the attribute names associated to the current session. It returns the enumeration of attribute names present in session.
Enumerator e = request.getAttributeNames();
setAttribute(String,Object) – It assigns an object’s value to the attribute. For example I have an attribute password and a String object str which has a value “admin” then calling request.setAttribute(“password”, str) would assign a value admin to the attribute password.
removeAttribute(String) – By using this method a attribute can be removed and cannot be used further. For e.g. If you have a statement request.removeAttribute(“userid”) on a JSP page then the userid attribute would be completely removed and request.getAttribute(“userid”) would return NULL if used after the removeAttribute method.
getCookies() – It returns an array of cookie objects received from the client. This method is mainly used when dealing with cookies in JSP.
getHeader(String name) – This method is used to get the header information of the request.
getHeaderNames() – Returns enumerator of all header names. Below code snippet would display all the header names associated with the request.

Enumeration e = request.getHeaderNames();

while (enumeration.hasMoreElements()) {

String str = (String)e.nextElement();

out.println(str);

}
getRequestURI() – This method (request.getRequestURI()) returns the URL of current JSP page.
getMethod() - It returns HTTP request method. request.getMethod(). For example it will return GET for a Get request and POST for a Post Request.
getQueryString() – Used for getting the query string associated to the JSP page URL. It is the string associted to the URL after question mark sign (?).

Request Implicit Object Example:

In the below example we are receiving the input from user in index.html page and displaying the same information in userinfo.jsp page using request implicit object.

index.html

<html>

<head>

<title>Enter UserName and Password</title>

</head>

<body>

<form action="userinfo.jsp">

Enter User Name: <input type="text" name="uname" /> <br><br>

Enter Password: <input type="text" name="pass" /> <br><br>

<input type="submit" value="Submit Details"/>

</form>

</body>

</html>

userinfo.jsp:

<%@ page import = " java.util.* " %>

<html>

<body>

<%

String username=request.getParameter("uname");

String password=request.getParameter("pass");

out.print("Name: "+username+" Password: "+password);

%>

</body>

</html>

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