##HTTP:
*概念:Hyper Text Transfer Protocol 超文本传输协议
*传输协议:定义了,客户端和服务器端通信是,发送数据的格式
*特点:
1.基于TCP/IP的高级协议
2.默认端口号:80
3.基于请求/响应模型的:一次请求对应一次响应
4.无状态的:每次请求之间相互独立,不能交互数据
*历史版本(了解):
*1.0:每一次请求响应都会建立新的链接
*1.1:复用链接
*请求消息数据格式
1.请求行
请求方式 请求url 请求协议/版本
GET /login.html HTTP/1.1
*请求方式:
*HTTP协议中有七种请求方式,常用的有2种
*GET:
1.请求的参数在请求行中,在url后
2.请求的url长度有限制的
3.不太安全
*POST:
1.请求的参数在请求体中
2.请求的url长度没有限制的
3.相对安全
2.请求头:客户端浏览器告诉服务器一些信息
请求头名称:请求头值
*常见的请求头:
1.User-Agent:浏览器告诉服务器,我访问你使用的浏览器版本信息
*可以再服务器端获取该头的信息,解决浏览器的兼容性问题
2.Referer:http://localhost/login.html
*告诉服务器,我(当前请求)从哪里来
*作用:
1.防盗链
2.统计工作
3.请求空行
空行,就是用于分割POST请求的请求头和请求体的
4.请求体(正文):
*封装POST请求消息的请求参数的
##Request:
1、request对象和response对象的原理
1.request和response对象是由服务器创建的。我们来使用他们
2.request对象是来获取请求消息,response对象是来设置响应消息
2、request对象继承体系结构:
ServletRequest -- 接口
继承
HttpServletRequest -- 接口
实现
org.apache.catalina.connector.RequestFacade 类(tomcat)
3、request功能:
1.获取请求消息数据
1.获取请求行数据
*GET /day/demo1? name=zhangsan HTTP/1.1
*方法:
1.获取请求方式:GET
*String getMethod()
2.(*)获取虚拟目录:/day14
*String getContextPath()
3.获取Servlet路径:/demo1
*String getServletPath()
4.获取get方式请求参数:name=zhangsan
*String getQueryString()
5.(*)获取请求URI:/day14/demo1
*String getRequestURI()
*StringBuffer getRequestURL() :http://localhost/day14/demo1
*URL:统一资源定位符:http://localhost/day14/demo1
*URI:统一资源标识符:/day14/demo1
6.获取协议及版本:HTTP/1.1
*String getProtocol()
7.获取客户机的IP地址:
*String getRemoteAddr()
package Study_Request;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.获取请求方式:GET
String method = request.getMethod();
System.out.println(method);
//2.获取虚拟目录:
String contextPath = request.getContextPath();
System.out.println(contextPath);
//3.获取Servlet路径
String servletPath = request.getServletPath();
System.out.println(servletPath);
//4.获取get方式请求参数:
String queryString = request.getQueryString();
System.out.println(queryString);
//5.获取请求URI
String requestURI = request.getRequestURI();
StringBuffer requestURL = request.getRequestURL();
System.out.println(requestURI);
System.out.println(requestURL);
//6.获取协议及版本
String protocol = request.getProtocol();
System.out.println(protocol);
//7.获取客户机的IP地址
String remoteAddr = request.getRemoteAddr();
System.out.println(remoteAddr);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
2.获取请求头数据
*方法:
*(*)String getHeader(String name):通过请求头的名称获取请求头的值
*Enumeration<String> getHeaderNames():获取所有的请求头名称
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//演示获取请求投数据
//1.获区所有请求头名称
Enumeration<String> headerNames = request.getHeaderNames();
//2.遍历
while(headerNames.hasMoreElements()){
String name = headerNames.nextElement();
//根据名称获取请求头的值
String value = request.getHeader(name);
System.out.println(name+"----<"+value);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//演示获取请求头数据:user-agent
String agent = request.getHeader("user-agent");
//判断agent的浏览器版本
if(agent.contains("Chrome")){
//谷歌
System.out.println("谷歌来了.....");
}else if(agent.contains("Edge")){
System.out.println("Edge来了....");
}
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//演示获取请求头数据:referer
String referer = request.getHeader("referer");
System.out.println(referer);
//防盗链
if(referer != null){
if(referer.contains("/web_br")){
//正藏访问
System.out.println("播放电影");
}else {
//倒链
System.out.println("滚一边去,别盗版我的");
}
}
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
3.获取请求体数据:
*请求体:只有POST请求方式,才有请求体,在请求体中封装了POST请求的请求参数
*步骤:
1.获取流对象:
*BufferedReader getReader():获取字符输入流,只能操作字符数据
*ServletInputStream getInputStream():获取字节输入流,可以操作所有类型数据
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="/requestDemo1" method="post">
<input type="text" name="username"><br>
<input type="text" name="password"><br>
<input type="submit" value="注册">
</form>
</body>
</html>
package Study_Request;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取请求消息体
//1.获取字符流
BufferedReader br = request.getReader();
//2.读取数据
String line = null;
while((line = br.readLine()) != null){
System.out.println(line);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
2.再从流对象中拿数据
2.其他功能:
1.获取请求参数通用方式
1.String getParameter(String name):根据参数名称获取参数值
2.String[ ] getParameterValues (String name):根据参数名称获取参数值得数组
3.Enumeration<String> getParamterNames():获取所有请求的参数名称
4.Map<String,String[ ]> getParameterMap():获取所有参数的map集合
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="/requestDemo2" method="get">
<input type="text" name="username"><br>
<input type="text" name="password"><br>
<input type="checkbox" name="hobby" value="study">学习
<input type="checkbox" name="hobby" value="play">游戏
<input type="submit" value="注册">
</form>
</body>
</html>
package Study_Request;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;
@WebServlet("/requestDemo2")
public class RequestDemo2 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//post获取请求参数
/* //根据参数名称获取参数值
String username = request.getParameter("username");
System.out.println("post");
System.out.println(username);*/
/* //根据参数名称获取参数值得数组
String[] hobbies = request.getParameterValues("hobby");
for (String hobby : hobbies) {
System.out.println(hobby);
}*/
/* //获取所有请求的参数名称
Enumeration<String> parameterNames = request.getParameterNames();
while (parameterNames.hasMoreElements()){
String s = parameterNames.nextElement();
System.out.println(s);
String value = request.getParameter(s);
System.out.println(value);
System.out.println("-----------------------------");
}*/
//获取所有参数的map集合
Map<String, String[]> parameterMap = request.getParameterMap();
//遍历
Set<String> keyset = parameterMap.keySet();
for (String name : keyset) {
//获取键获取值
String[] values = parameterMap.get(name);
System.out.println(name);
for (String value : values) {
System.out.println(value);
}
System.out.println("--------------------------------");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//get 获取请求参数
/* //根据参数名称获取参数值
String username = request.getParameter("username");
System.out.println("get");
System.out.println(username);*/
this.doPost(request,response);
}
}
*中文乱码问题:
*get方式:tomcat 8 已经将get方式乱码问题解决了
*post方式:会乱码
*解决:在获取参数前,设置request的编码为:
request.setCharacterEncoding("UTF-8")
2.请求转发:一种在服务器内部的资源跳转方式
1.步骤:
1.通过request对象获取请求转发器对象:
RequestDispatcher getRequestDispatcher(String path)
2.使用RequestDispatcher对象来进行转发:
forward(ServletRequest request,ServletResponse reponse)
2.特点:
1.浏览器地址栏路径不发生变化
2.只能转发到当前服务器内部资源中
3.转发是一次请求
package Study_Request;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("demo4444被访问了..............");
//转发资源到demo5
request.getRequestDispatcher("/requestDemo5").forward(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
package Study_Request;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/requestDemo5")
public class RequestDemo5 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("demo5555被访问了...................");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
3.共享数据 :
*域对象:一个有作用范围的对象,可以在范围内共享数据
*request域:代表一次请求的范围,一般用于请求转发的多个资源中共享数据
*方法:
1.void setAttribute(String name,Object obj):存储数据
2.Object getAttitude(String name):通过键获取值
3.void removeAttribute(String name):通过键移除键值对
4.获取ServletContext:
*ServletContext getServletContext()
## 案例:用户登录
*用户登录案例需求:
1.编写login.html登录页面
username&password 两个输入框
2.使用Druid数据库链接池技术,操作mysql,day14数据库中user表
3.使用JdbcTemplete技术封装JDBC
4.登录成功跳转到SuccessServlet展示:登录成功! 用户名欢迎您
5.登录失败跳转到FailServlet展示:登录失败,用户名或密码错误
分析: