With Java Servlet API, it is quite easy to send and receive HTTP headers. Below code examples shows the details.
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Reading Headers
A servlet can read HTTP headers sent by a client request using HttpServletRequest interface. This interface has two methods for this.
String getHeader(String headerName);
int getintHeader(String headerName);
Both these methods are similar except getIntHeader() method is used to return value of headers with int type values. Below code shows how value of "Content-type" header is read from the user request. (HttpServlet.doGet() method is used in the example).
import javax.servlet.http.*;
import java.io.*;
public class MyServlet extends HttpServlet {
public void doGet(re, res) throws IOException{
String contentType = request.getHeader("Content-type");
//....
}
}
Creating/Writing Headers
A servlet can create a header and send back to the client using HttpServletResponse interface; using the following setter methods.
void setHeader(String headerName, String headerValue);
int setintHeader(String headerName, int headerValue);
Below code shows how a new header named "My_Header" is created and set on response.
import javax.servlet.http.*;
import java.io.*;
public class MyServlet extends HttpServlet {
public void doGet(re, res) throws IOException{
response.setHeader("My_Header", "new Header value");
//....
}
}
Now the client (generally the browser) will receive this new header.
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