Description
As examined in past chapter, when a Web server reacts to a HTTP request to the client, the response regularly comprises of a status line, some response headers, and the record. The response will be as follows.
HTTP/1.1 200 OK Content-Type: text/html Header2: ... ... HeaderN: ... (Blank Line) <!doctype ...> <html> <head>...</head> <body> ... </body> </html>
The status line comprises of the HTTP variant (HTTP/1.1 in the illustration), a status code (200 in the case), and a short message relating to the status code (OK in the case).
Methods
Servlet Response, Following are the regularly using methods of Http Servlet Response.
| Methods | Description |
|---|---|
| String encodeRedirectURL(String url) | Encodes the predetermined URL for use in the sendRedirect method. |
| boolean isCommitted() | It returns boolean when response is commited. |
| void addCookie(Cookie cookie) | It is utilized to add the cookie to the response. |
| void setContentType(String type) | To set the content type while sending to the client from the server. |
Example
MyServletDemo.java
Enter the name and click on the login button, following is the output will be displayed.
package servletresponse;
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
public class MyServletDemo extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res)
throws ServletException,IOException
{
res.setContentType("text/html");
PrintWriter pwriter=res.getWriter();
String name=req.getParameter("uname");
pwriter.println("User Details Page:");
pwriter.println("Hello "+name);
pwriter.close();
}
}
The doGet() Method. A GET request results from an normal request for a URL or from a HTML web form that has no METHOD determined and it ought to be taken care of by doGet() technique.
web.xml
<web-app> <servlet> <servlet-name>DemoServlet</servlet-name> <servlet-class>servletresponse.MyServletDemo</servlet-class> </servlet> <servlet-mapping> <servlet-name>DemoServlet</servlet-name> <url-pattern>/mydetails</url-pattern> </servlet-mapping> </web-app>
Make sure that servlet name should be same as that is DemoServlet in both the tags. URL pattern should be match with below HTML page action form.
index.html
<form action="./mydetails" method="get"> User name: <input type="text" name="uname"> <input type="submit" value="login"> </form>
Here the developer just created the User name and submit button that is login.
Output
The following output is generated by compiling the above code.
- ServletResponse available in javax.servlet package where as HttpServletResponse available in javax.servlet.http package and it’s a sub interface of ServletResponse.
- ServletResponse will have methods as getWriter() etc. and HttpServletResponse also have methods like encodeURL() and sendRedirect() etc and it will hire the methods from ServletResponse.
- ServletResponse is a protocol independent and HttpServletResponse is a protocol dependent.
Key Points
- Servlet Response – While compiling the program some time an error 500 will occur which means it’s a server error.
- Servlet Response – In the servlet class, package name with class name needs to be written