Java Tutorial/Servlet/Introduction

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Версия от 17:44, 31 мая 2010; (обсуждение)
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Get all Server Related Parameters

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
  public void service(ServletRequest req, ServletResponse res)       
                             throws ServletException, IOException {  
    res.setContentType("text/plain");                                
    PrintWriter out = res.getWriter();                               
    ServletContext context = getServletContext();
    out.println("req.getServerName(): " + req.getServerName());      
    out.println("req.getServerPort(): " + req.getServerPort());      
    out.println("context.getServerInfo(): " + context.getServerInfo());
    out.println("getServerInfo() name: " +                           
                 getServerInfoName(context.getServerInfo()));
    out.println("getServerInfo() version: " +                        
                 getServerInfoVersion(context.getServerInfo()));
    out.println("context.getAttributeNames():");
    Enumeration e = context.getAttributeNames();
    while (e.hasMoreElements()) {
      String name = (String) e.nextElement();
      out.println("  context.getAttribute(\"" + name + "\"): " +
                     context.getAttribute(name));
    }
  }
  private String getServerInfoName(String serverInfo) {
    int slash = serverInfo.indexOf("/");
    if (slash == -1) return serverInfo;
    else return serverInfo.substring(0, slash);
  }
  private String getServerInfoVersion(String serverInfo) {
    // Version info is everything between the slash and the space
    int slash = serverInfo.indexOf("/");
    if (slash == -1) return null;
    int space = serverInfo.indexOf(" ", slash);
    if (space == -1) space = serverInfo.length();
    return serverInfo.substring(slash + 1, space);
  }
}





List All Init Parameters in Servlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
  public void service(ServletRequest req, ServletResponse res)
                             throws ServletException, IOException {
    res.setContentType("text/plain");
    PrintWriter out = res.getWriter();
    out.println("Init Parameters:");
    Enumeration e = getInitParameterNames();
    while (e.hasMoreElements()) {
      String name = (String) e.nextElement();
      out.println(name + ": " + getInitParameter(name));
    }
  }
}





Servlet Converter from Kilometers to Miles

/**
*  Copyright (c) 2002 by Phil Hanna
*  All rights reserved.
*  
*  You may study, use, modify, and distribute this
*  software for any purpose provided that this
*  copyright notice appears in all copies.
*  
*  This software is provided without warranty
*  either expressed or implied.
*/
import java.text.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet {
   
   /**
   * Numeric format used to display temperatures
   */
   private static final DecimalFormat FMT
      = new DecimalFormat("#0.00");
   /**
   * Factor to convert from km/l to mi/gal
   */
   private static final double CONVERSION_FACTOR = 2.352145;
   /**
   * Handles a GET request
   */
   public void doGet(
         HttpServletRequest request,
         HttpServletResponse response)
      throws ServletException, IOException
   {
      // Set up for creating HTML output
      response.setContentType("text/html");
      PrintWriter out = response.getWriter();
      // Generate heading
      out.println
         ( "<html>"
         + "<head>"
         + "<title>Fuel Efficiency Conversion Chart</title>"
         + "</head>"
         + "<body>"
         + "<center>"
         + "<h1>Fuel Efficiency Conversion Chart</h1>"
         + "<table border="1" cellpadding="3" cellspacing="0">"
         + "<tr>"
         + "<TH>Kilometers per Liter</th>"
         + "<TH>Miles per Gallon</th>"
         + "</tr>"
         );
      // Generate table
      for (double kmpl = 5; kmpl <= 20; kmpl += 1.0) {
         double mpg = kmpl * CONVERSION_FACTOR;
         out.println
            ( "<tr>"
            + "<td align="right">" + FMT.format(kmpl) + "</td>"
            + "<td align="right">" + FMT.format(mpg) + "</td>"
            + "</tr>"
            );
      }
      // Generate footer
      out.println
         ( "</table>"
         + "</center>"
         + "</body>"
         + "</html>"
         );
   }
}





Setup Servlet Environment

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet 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>");
  }
}





Your First Servlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet 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>");
  }
}


Источник — «http://jexp.ru/index.php?title=Java_Tutorial/Servlet/Introduction&oldid=4891»