1、请求 HttpServletRequest 响应 HttpServletResponse

请求头、请求行、请求体（请求参数）。

package net.pp.servlet;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.swing.*;
import java.io.IOException;
import java.util.Enumeration;public class HelloService extends HttpServlet{@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException{//请求 HttpServletRequest//获取请求行System.out.println("接收到get请求");System.out.println("请求方式：" +request.getMethod());System.out.println("URL：" +request.getRequestURL());System.out.println("发出请求客户端IP地址："  +request.getRemoteAddr());System.out.println("服务点接收请求的IP地址：" +request.getLocalAddr());System.out.println("访问客户端的端口号：" +request.getRemotePort());System.out.println("WEB应用路径：" +request.getContextPath());System.out.println("HTTP协议和版本" +request.getProtocol());//获取请求头Enumeration<String> headerNames = request.getHeaderNames();while (headerNames.hasMoreElements()){String element = headerNames.nextElement();System.out.println(element+"："+request.getHeader(element));}//获取请求参数String name = request.getParameter("name");String passWord = request.getParameter("passWord");System.out.println("用户名：" + name);System.out.println("密码：" + passWord);//响应 HttpServletResponseString result = "恭喜您登陆成功";//法一：ServletOutputStream outputStream = response.getOutputStream();outputStream.write(result.getBytes());//法二：response.setContentType("text/html;charset=utf-8");//将iso转化为utf-8,否则会出现码PrintWriter writer = response.getWriter();writer.write(result);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{System.out.println("接收到post请求");}}

get.html

<center><h2>发起HTTP get请求</h2><form action="hi" method="get"><p>账号：<input type="text" name="name" /></p><p>密码：<input type="text" name="passWord" /></p><input type="submit" value="提交" /></form></center>

结果如下：

2、ServletContext对象

ServletContext对象是它对应的Web应用环境的相关配置信息

应用：

1）获取整个Web项目初始化参数；

2）在多个Servlet中共享数据；

3）读取Web项目中的资源文件。

1.获取整个Web项目初始化参数；

ServletTest2.java

package net.pp.servlet;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(name = "ServletTest2", urlPatterns = "/test2")
public class ServletTest2 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//利用getServletContext()获取全局变量String encoding = this.getServletContext().getInitParameter("encoding");this.getServletContext().getInitParameterNames();System.out.println(encoding);}
}

结果是：

2.在多个Servlet中共享数据

ServleTest3.java

package net.pp.servlet;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(name = "ServletTest3", urlPatterns = "/test3")
public class ServletTest3 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String data = "pengpeng";this.getServletContext().setAttribute("name", data);}
}

ServleTest4.java

package net.pp.servlet;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(name = "ServletTest4", urlPatterns = "/test4")
public class ServletTest4 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String name = (String) this.getServletContext().getAttribute("name");System.out.println(name);}
}

结果是：

3）读取Web项目中的资源文件

ServletTest5.java

package net.pp.servlet;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.io.InputStream;
import java.util.Properties;@WebServlet(name = "ServletTest5", urlPatterns = "/test5")
public class ServletTest5 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {InputStream resourceAsStream = this.getServletContext().getResourceAsStream("/db.properties");Properties properties = new Properties();properties.load(resourceAsStream);String name = properties.getProperty("name");String password = properties.getProperty("passWord");String url = properties.getProperty("url");System.out.println(url);System.out.println(name);System.out.println(password);}
}

db,properties

url=jdbc:mysql://localhost:3306
name = mysql of pengpeng
passWord = 888888

结果是：

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Servlet请求和响应

1、请求 HttpServletRequest 响应 HttpServletResponse

2、ServletContext对象

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