学习笔记，仅供参考，有错必纠

文章目录

• ​​request​​

• ​​Request的功能​​

• ​​举个例子​​

• ​​获取请求参数通用方式(get,post都可用)​​

• ​​举个例子​​

• ​​中文乱码问题​​
• ​​请求转发​​

• ​​请求转发的特点​​
• ​​举个例子​​

request

Request的功能

//1.获取请求方式
String getMethod()
//2.获取虚拟目录
String getContextPath()
//3.获取Servlet路径
String getServletPath()
//4.获取Get方式请求参数
String getQueryString()
//5.获取请求UrI
//String    getRequestURI()
//5.获取请求UrL
//String    getRequestURL()
//6.获取协议及版本
String getProtocol()
//7.获取客户机IP地址
String getRemoteAddr()

举个例子

利用postman向如下url发送post请求：

http://localhost:8080/ServletDemo/demo05?name=goatbishop

控制台输出如下结果：

获取请求方式 : GET
获取虚拟目录 : /ServletDemo
获取Servlet路径 /demo05
获取Get请求参数 : name=goatbishop
获取请求URI : /ServletDemo/demo05
获取请求URL  : http://localhost:8080/ServletDemo/demo05
获取协议及版本 : HTTP/1.1
获取客户机IP地址 : 0:0:0:0:0:0:0:1
获取请求头数据 : PostmanRuntime/7.25.0

获取请求参数通用方式(get,post都可用)

根据参数名称获取参数值：

String getParameter(String name)

根据参数名称获取参数值数组，通常用于复选框之类：

String[] getParametervalues(String name)

举个例子

• 例子1

package com.servlet.demo;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/demo06")
public class Demo06 extends HttpServlet{
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
//    super.doPost(req, resp);
    this.doGet(req, resp);
  }
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
//    super.doGet(req, resp);
    //获取参数名为user_name的参数值
    System.out.println(req.getParameter("user_name"));
  }
}

向http://localhost:8080/ServletDemo/demo06?user_name=goatbishop发送POST请求：

控制台输出：

goatbishop

• 例子2

package com.servlet.demo;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/demo07")
public class Demo07 extends HttpServlet{
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
    String[] bunny = req.getParameterValues("bunny");
    for (String b : bunny) {
      System.out.println(b);
    }
    
  }
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
    this.doGet(req, resp);
    
  }
  
}

向http://localhost:8080/ServletDemo/demo07?bunny=Huang&bunny=Bai发起请求：

控制台输出：

Huang
Bai

中文乱码问题

Tomcat8已经把get方式的中文乱码问题解决了

Post方式乱码解决：

//在获取参数前设置request的编码,使之和页面保持一致

Request.setCharacterEncoding(“utf-8”)

请求转发

图式：

请求转发是一种在服务器内部的资源跳转方式：

req.getRequestDispatcher(String path).forward(ServletRequest request,ServletResponse response);

请求转发的特点

• 浏览器地址栏路径不发生变化
• 只能转发到当前服务器内部资源
• 转发是一次请求

举个例子

Demo08.html

package com.servlet.demo;


import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/demo08")
public class Demo08 extends HttpServlet{
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
//    super.doGet(req, resp);
    System.out.println("这是demo08");
    req.getRequestDispatcher("/demo09").forward(req, resp);
    
  }
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
//    super.doPost(req, resp);
    this.doGet(req, resp);
    
  }
  
}

Demo09.html：

package com.servlet.demo;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/demo09")
public class Demo09 extends HttpServlet{
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
//    super.doGet(req, resp);
    System.out.println("这是demo09");
  }
  
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    // TODO Auto-generated method stub
//    super.doPost(req, resp);
    this.doGet(req, resp);
  }
}

向http://localhost:8080/ServletDemo/demo08发起POST请求，得到控制台输出：

这是demo08
这是demo09