Java Tutorial/Servlet/Introduction
Содержание
Get all Server Related Parameters
<source lang="java">
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);
}
}</source>
List All Init Parameters in Servlet
<source lang="java">
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));
}
}
}</source>
Servlet Converter from Kilometers to Miles
<source lang="java">
/**
- 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>"
+ "Fuel Efficiency Conversion Chart
" + "| Kilometers per Liter | " + "Miles per Gallon | " + "
|---|---|
| " + FMT.format(kmpl) + " | " + "" + FMT.format(mpg) + " | " + "
+ "</body>"
+ "</html>"
);
}
}</source>
Setup Servlet Environment
<source lang="java">
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("Hello World");
out.println("</BODY></HTML>");
}
}</source>
Your First Servlet
<source lang="java">
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("Hello World");
out.println("</BODY></HTML>");
}
}</source>
