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java ee web工程师培训-凯发ag旗舰厅登录网址下载
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java ee web工程师培训-jdbc servlet jsp整合开发之14.servlet请求头信息
小编觉得挺不错的,现在分享给大家,帮大家做个参考.
–典型的请求头信息
–读取http请求头
–使用表格显示所有请求头信息
–理解各种请求头的含义
–区分不同的浏览器类型 ##############michael分割线################### • 典型的请求头信息 • 读取http请求头
–使用httpservletrequest中的方法
• 一般方法
–getheader (header名称不区分大小写)
–getheaders
–getheadernames
• 专门方法
–getcookies
–getauthtype
–getremoteuser
–getcontentlength
–getcontenttype
–getdateheader
–getintheader
• 相关信息
–getmethod
–getrequesturi
–getquerystring
–getprotocol • 使用表格显示有请求头信息 login.html <!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>login.htmltitle>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<!--rel="stylesheet" type="text/css" href="./styles.css">-->
head>
<body>
<form name="f1" id="f1" action="/servlet_requestheader/servlet/requestheaderservlet" method="post">
<table border="0">
<tr>
<td>login:td>
<td><input type="text" name="login" id="login">td>
tr>
<tr>
<td>password:td>
<td><input type="password" name="password" id="password">td>
tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="login">td>
tr>
table>
form>
body>
html>
requestheaderservlet.java package com.michael.servlet;
import java.io.ioexception;
import java.io.printwriter;
import java.util.enumeration;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class requestheaderservlet extends httpservlet {
/**
* constructor of the object.
*/
public requestheaderservlet() {
super();
}
/**
* destruction of the servlet.
*/
public void destroy() {
super.destroy(); // just puts "destroy" string in log
// put your code here
}
/**
* the doget method of the servlet.
*
* this method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request,response);
}
/**
* the dopost method of the servlet.
*
* this method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
enumeration names = request.getheadernames();
response.setcontenttype("text/html");
printwriter out = response.getwriter();
out
.println("//w3c//dtd html 4.01 transitional//en\">");
out.println("");
out.println("a servlet ");
out.println(" ");
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
while(names.hasmoreelements()){
string name = (string) names.nextelement();
string value = request.getheader(name);
out.println("");
out.println("");
out.println("");
out.println("");
}
out.println("
");
out.println(" ");
out.println("");
out.flush();
out.close();
}
/**
* initialization of the servlet.
*
* @throws servletexception if an error occure
*/
public void init() throws servletexception {
// put your code here
}
}
看下效果 • 理解各种请求头的含义
– accept
• 标识浏览器能处理mime类型
• 能发送不同的内容到不同的客户端. 例如，png文件有好的压缩特性，但是在浏览器中支持的不是很广泛。
• 一个servlet可以检查是否支持png文件格式，如果支持
– 否则
–
– accept-encoding
• 标识浏览器能处理的编码类型
– authorization
• 授权信息，通常出现在对服务器发送的www-authenticate头的应答中
– connection
• 表示是否需要持久连接。如果servlet看到这里的值为“keep-alive”，或者看到请求使用的是http 1.1（http 1.1默认进行持久连接），它就可以利用持久连接的优点，当页面包含多个元素时（例如applet，图片），显著地减少下载所需要的时间。要实现这一点，servlet需要在应答中发送一个content-length头，最简单的实现方法是：先把内容写入bytearrayoutputstream，然后在正式写出内容之前计算它的大小。
– cookie
• 参考java ee web工程师培训-jdbc servlet jsp整合开发之16.cookie –host
• 包含一个url，用户从该url代表的页面出发访问当前请求的页面
–if-modified-since
• 只有当所请求的内容，在指定的日期之后，又经过修改才返回它，否则返回304“not modified”应答
–referer
• 包含一个url，用户从该url代表的页面出发访问当前请求的页面。
–user-agent
• 浏览器类型，如果servlet返回的内容与浏览器类型有关则该值非常有用。 • 区分不同的浏览器类型 browsertypeservlet.java package com.michael.servlet;
import java.io.ioexception;
import java.io.printwriter;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class browsertypeservlet extends httpservlet {
/**
* constructor of the object.
*/
public browsertypeservlet() {
super();
}
/**
* destruction of the servlet.
*/
public void destroy() {
super.destroy(); // just puts "destroy" string in log
// put your code here
}
/**
* the doget method of the servlet.
*
* this method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request,response);
}
/**
* the dopost method of the servlet.
*
* this method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
string browsername = request.getheader("user-agent");
string result="";
if(browsername.indexof("msie")!=-1){
result = "您当前使用的浏览器是ie!";
}else{
result = "您当前使用的浏览器是firefox!";
}
response.setcontenttype("text/html;charset=gbk");
printwriter out = response.getwriter();
out
.println("//w3c//dtd html 4.01 transitional//en\">");
out.println("");
out.println("a servlet ");
out.println(" ");
out.println(result);
out.println(" ");
out.println("");
out.flush();
out.close();
}
/**
* initialization of the servlet.
*
* @throws servletexception if an error occure
*/
public void init() throws servletexception {
// put your code here
}
}
测试 ok! ##############michael分割线###################
–读取http请求头
–使用表格显示所有请求头信息
–理解各种请求头的含义
–区分不同的浏览器类型 ##############michael分割线################### • 典型的请求头信息 • 读取http请求头
–使用httpservletrequest中的方法
• 一般方法
–getheader (header名称不区分大小写)
–getheaders
–getheadernames
• 专门方法
–getcookies
–getauthtype
–getremoteuser
–getcontentlength
–getcontenttype
–getdateheader
–getintheader
• 相关信息
–getmethod
–getrequesturi
–getquerystring
–getprotocol • 使用表格显示有请求头信息 login.html <!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>login.htmltitle>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<!--rel="stylesheet" type="text/css" href="./styles.css">-->
head>
<body>
<form name="f1" id="f1" action="/servlet_requestheader/servlet/requestheaderservlet" method="post">
<table border="0">
<tr>
<td>login:td>
<td><input type="text" name="login" id="login">td>
tr>
<tr>
<td>password:td>
<td><input type="password" name="password" id="password">td>
tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="login">td>
tr>
table>
form>
body>
html>
requestheaderservlet.java package com.michael.servlet;
import java.io.ioexception;
import java.io.printwriter;
import java.util.enumeration;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class requestheaderservlet extends httpservlet {
/**
* constructor of the object.
*/
public requestheaderservlet() {
super();
}
/**
* destruction of the servlet.
*/
public void destroy() {
super.destroy(); // just puts "destroy" string in log
// put your code here
}
/**
* the doget method of the servlet.
*
* this method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request,response);
}
/**
* the dopost method of the servlet.
*
* this method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
enumeration names = request.getheadernames();
response.setcontenttype("text/html");
printwriter out = response.getwriter();
out
.println("//w3c//dtd html 4.01 transitional//en\">");
out.println("");
out.println("
out.println(" ");
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
while(names.hasmoreelements()){
string name = (string) names.nextelement();
string value = request.getheader(name);
out.println("");
out.println("");
out.println("");
out.println("");
}
out.println("
| "); out.println("requestheader name"); out.println(" | "); out.println("requestheader value"); out.println(" |
|---|---|
| "); out.println(name); out.println(" | "); out.println(value); out.println(" |
out.println(" ");
out.println("");
out.flush();
out.close();
}
/**
* initialization of the servlet.
*
* @throws servletexception if an error occure
*/
public void init() throws servletexception {
// put your code here
}
}
看下效果 • 理解各种请求头的含义
– accept
• 标识浏览器能处理mime类型
• 能发送不同的内容到不同的客户端. 例如，png文件有好的压缩特性，但是在浏览器中支持的不是很广泛。
• 一个servlet可以检查是否支持png文件格式，如果支持
– 否则
–
– accept-encoding
• 标识浏览器能处理的编码类型
– authorization
• 授权信息，通常出现在对服务器发送的www-authenticate头的应答中
– connection
• 表示是否需要持久连接。如果servlet看到这里的值为“keep-alive”，或者看到请求使用的是http 1.1（http 1.1默认进行持久连接），它就可以利用持久连接的优点，当页面包含多个元素时（例如applet，图片），显著地减少下载所需要的时间。要实现这一点，servlet需要在应答中发送一个content-length头，最简单的实现方法是：先把内容写入bytearrayoutputstream，然后在正式写出内容之前计算它的大小。
– cookie
• 参考java ee web工程师培训-jdbc servlet jsp整合开发之16.cookie –host
• 包含一个url，用户从该url代表的页面出发访问当前请求的页面
–if-modified-since
• 只有当所请求的内容，在指定的日期之后，又经过修改才返回它，否则返回304“not modified”应答
–referer
• 包含一个url，用户从该url代表的页面出发访问当前请求的页面。
–user-agent
• 浏览器类型，如果servlet返回的内容与浏览器类型有关则该值非常有用。 • 区分不同的浏览器类型 browsertypeservlet.java package com.michael.servlet;
import java.io.ioexception;
import java.io.printwriter;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class browsertypeservlet extends httpservlet {
/**
* constructor of the object.
*/
public browsertypeservlet() {
super();
}
/**
* destruction of the servlet.
*/
public void destroy() {
super.destroy(); // just puts "destroy" string in log
// put your code here
}
/**
* the doget method of the servlet.
*
* this method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void doget(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
dopost(request,response);
}
/**
* the dopost method of the servlet.
*
* this method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws servletexception if an error occurred
* @throws ioexception if an error occurred
*/
public void dopost(httpservletrequest request, httpservletresponse response)
throws servletexception, ioexception {
string browsername = request.getheader("user-agent");
string result="";
if(browsername.indexof("msie")!=-1){
result = "您当前使用的浏览器是ie!";
}else{
result = "您当前使用的浏览器是firefox!";
}
response.setcontenttype("text/html;charset=gbk");
printwriter out = response.getwriter();
out
.println("//w3c//dtd html 4.01 transitional//en\">");
out.println("");
out.println("
out.println(" ");
out.println(result);
out.println(" ");
out.println("");
out.flush();
out.close();
}
/**
* initialization of the servlet.
*
* @throws servletexception if an error occure
*/
public void init() throws servletexception {
// put your code here
}
}
测试 ok! ##############michael分割线###################
总结
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