一、Request原理和继承体系
. request对象和response对象的原理
1. request和response对象是由服务器创建的。我们来使用它们
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)二、Request功能
1、获取请求行数据
. 获取请求消息数据
1. 获取请求行数据
* GET /day14/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(): /day14/demo1
* StringBuffer getRequestURL() :http://localhost/day14/demo1
* URL:统一资源定位符 ： http://localhost/day14/demo1 中华人民共和国
* URI：统一资源标识符 : /day14/demo1 共和国
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 cn.itcast.web.request;
import com.sun.scenario.effect.impl.sw.sse.SSEBlend_SRC_OUTPeer;
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("/requestDemo1")
public class RequestDemo1 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取请求方式
String method = request.getMethod();
System.out.println(method);
//获取虚拟目录
String contextPath = request.getContextPath();
System.out.println(contextPath);
//获取Servlet路径
String servletPath = request.getServletPath();
System.out.println(servletPath);
//获取get方式请求参数
String queryString = request.getQueryString();
System.out.println(queryString);
//获取请求URI
String requestURI = request.getRequestURI();
System.out.println(requestURI);
StringBuffer requestURL = request.getRequestURL();
System.out.println(requestURL);
//获取协议及版本
String protocol = request.getProtocol();
System.out.println(protocol);
//获取客户机的IP地址
String remoteAddr = request.getRemoteAddr();
System.out.println(remoteAddr);
}
}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
----------------------------------
@WebServlet("/requestDemo2")
public class RequestDemo2 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
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...");
} else if(agent.contains("Firefox")) {
System.out.println("火狐...");
}
}
}
----------------------------------
@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
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("/day14")) {
System.out.println("正常的");
}else {
System.out.println("盗链");
}
}
}
}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
* 在文件上传知识点后讲解
2. 再从流对象中拿数据
-----------------------------------
@WebServlet("/requestDemo5")
public class RequestDemo5 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取请求消息体--请求参数
//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 {
}
}4、获取请求参数
. 获取请求参数通用方式：不论get还是post请求方式都可以使用下列方法来获取请求参数
1. String getParameter(String name):根据参数名称获取参数值 username=zs&password=123
2. String[] getParameterValues(String name):根据参数名称获取参数值的数组 hobby=xx&hobby=game
3. Enumeration<String> getParameterNames():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
--------------------------------
package cn.itcast.web.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;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;
@WebServlet("/requestDemo6")
public class RequestDemo6 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的数组
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 name = parameterNames.nextElement();
System.out.println(name);
String value = request.getParameter(name);
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) {
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("post");
// System.out.println(username);
this.doPost(request,response);
}
}5、中文乱码问题
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request.setCharacterEncoding("utf-8");6、请求转发
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 response)
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
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()
------------------------------------
@WebServlet("/requestDemo8")
public class RequestDemo8 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("demo8888被访问了。。。");
//转发到demo9资源
/*
RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");
requestDispatcher.forward(request,response);
*/
//存储数据到request域中
request.setAttribute("msg","hello");
request.getRequestDispatcher("/requestDemo9").forward(request,response);
//request.getRequestDispatcher("http://www.itcast.cn").forward(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
@WebServlet("/requestDemo9")
public class RequestDemo9 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取数据
Object msg = request.getAttribute("msg");
System.out.println(msg);
System.out.println("demo9999被访问了。。。");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
---------------------------
获取ServletContext
@WebServlet("/requestDemo10")
public class RequestDemo10 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext servletContext = request.getServletContext();
System.out.println(servletContext);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}