Sending a Normal Response

Let’s begin our discussion of servlet responses with another look at the first servlet in this book, the HelloWorld servlet, shown in Example 5.1. We hope it looks a lot simpler to you now than it did back in Chapter 2.

Example 5-1. Hello again

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class HelloWorld extends HttpServlet {

  public void doGet(HttpServletRequest req, HttpServletResponse res)
                               throws ServletException, IOException {

    res.setContentType("text/html");
    PrintWriter out = res.getWriter();

    out.println("<HTML>");
    out.println("<HEAD><TITLE>Hello World</TITLE></HEAD>");
    out.println("<BODY>");
    out.println("<BIG>Hello World</BIG>");
    out.println("</BODY></HTML>");
  }
}

This servlet uses two methods and a class that have been only briefly mentioned before. The setContentType() method of ServletResponse sets the content type of the response to be the specified type:

public void ServletResponse.setContentType(String type)

In an HTTP servlet, this method sets the Content-Type HTTP header.

The getWriter() method returns a PrintWriter for writing character-based response data:

public PrintWriter ServletResponse.getWriter() throws IOException

The writer encodes the characters according to whatever charset is given in the content type. If no charset is specified, as is generally the case, the writer uses the ISO-8859-1 (Latin-1) encoding appropriate for Western European languages. Charsets are covered in depth in Chapter ...

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