一、Request继承体系
1、Tomcat需要解析请求数据，封装为request对象，并且创建request对象传递到service方法中
2、使用request对象，查阅JavaEE API文档的HttServletRequest接口
代码示例查看request全类名：
import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.annotation.*; import java.io.IOException; @WebServlet("/demo2") public class ServletDemo2 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println(request); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); } }
访问demo2路径：
控制台输出全类名：
二、Request获取请求数据
请求数据分为3部分：
1、请求行：
GET/request-demo/req1?username=zhangsan HTTP/1.1
String getMethod()：获取请求方式：GET
String getContextPath()：获取虚拟目录（项目访问路径）：/request-demo
StringBuffer getRequestURL：获取URL（统一资源定位符）：http://localhost:8080/request-demo/req1
String getRequestURL()：获取URL（统一资源标识符）：/request-demo/req1
String getQueryString()：获取请求参数（GET方式）：username=zhangsan&password=123
以上方法代码示例：
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("/req1") public class RequestDemo1 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //String getMethod() ：获取请求方式：GET String method = req.getMethod(); System.out.println(method);//GET //String getContextPath()：获取虚拟目录(项目访问路径):/request-demo String contextPath = req.getContextPath(); System.out.println(contextPath); //StringBuffer getRequestURL:获取URL(统一资源定位符)：http://localhost:8080/request-demo StringBuffer url = req.getRequestURL(); System.out.println(url.toString()); //String getRequestURI()：获取URL(统一资源标识符)：/request-demo/req1 String uri = req.getRequestURI(); System.out.println(uri); //String getQueryString()：获取请求参数（GEI方式）：username=zhangsan String queryString = req.getQueryString(); System.out.println(queryString); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { } }
访问req1路径：
控制台输出：
2、请求头：
User-Agent：Mozilla/5.0 Chrome/91.0.4472.106
String getHeader(String name)：根据请求头名称，获取值
以上方法代码示例：
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("/req1") public class RequestDemo1 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //获取请求头：user-agent:浏览器版本信息 String agent = req.getHeader("user-agent"); System.out.println(agent); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { } }
访问req1路径：
控制台输出：
3、请求体：
username=superbaby&password=123
ServletInputStream getInputStream()：获取字节输入流
BufferedReader getReader()：获取字符输入流
post请求需要表单，req.html代码：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action="/Tomcate-demo2/req4" method="get"> <input type="text" name="username"><br> <input type="password" name="password"><br> <input type="submit"> </form> </body> </html>
获取post请求参数代码：
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("/req1") public class RequestDemo1 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //获取post请求体，请求参数 //1、获取字符输入流 BufferedReader br = req.getReader(); //2、读取数量 String line = br.readLine(); System.out.println(line); } }
访问req.html，并输出参数提交：
控制台输出：
