Servlet Response Send Error : Response « Servlet « Java Tutorial

1. Java Tutorial
2. Servlet
3. Response

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

public class MyServlet extends HttpServlet {
  
  public void doGet(HttpServletRequest req, HttpServletResponse res)
                               throws ServletException, IOException {
    res.setBufferSize(8 * 1024); // 8K buffer
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();

    int size = res.getBufferSize(); // returns 8096 or greater

    // Record the default size, in the log
    log("The default buffer size is " + size);

    out.println("The client won't see this");
    res.reset();
    out.println("And this won't be seen if sendError() is called");
    if (req.getParameter("important_parameter") == null) {
      res.sendError(res.SC_BAD_REQUEST, "important_parameter needed");
    }
  }
}

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
    "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

<web-app>
    <servlet><servlet-name>MyServletName</servlet-name>
             <servlet-class>MyServlet</servlet-class>

             
    </servlet>
    
    <servlet-mapping><servlet-name>MyServletName</servlet-name>
        <url-pattern>/index.html</url-pattern>
    </servlet-mapping>
</web-app>

25.13.Response
	25.13.1.	Servlet Response Send Redirect
	25.13.2.	Servlet Response Send Error
	25.13.3.	Servlet OutputStream
	25.13.4.	Get Servlet OutputStream from Servlet Response
	25.13.5.	HTTP Response