JavaWeb-Servlet(一)

<!--    servlet声明-->
    <servlet>
        <servlet-name> Servlet名字（自己定义的） </servlet-name>
        <servlet-class> 此处写完整的类名 </servlet-class>
    </servlet>
<!--    servlet访问方式的声明-->
    <servlet-mapping>
        <servlet-name>Servlet名字（自己定义的）</servlet-name>
        <url-pattern>访问路径</url-pattern>
    </servlet-mapping>

package com.company;
import javax.servlet.*;
import java.io.IOException;
public class Main  implements Servlet {
//    创建一个ServletConfig对象可以用来接收init传递的servletConfig
    private ServletConfig servletConfig;
//    初始化，在Servlet创建时候自动执行，特点是只会执行一次
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
//        通过数据范围上升一级实现能够获取ServletConfig信息
        this.servletConfig = servletConfig;
    }
//    获取Servlet类的相关配置数据
    @Override
    public ServletConfig getServletConfig() {
        return servletConfig;
    }
//    提供服务方法，特点是在每一次用户访问时候都能调用方法
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("执行服务方法");
    }
//    获取消息
    @Override
    public String getServletInfo() {
        return null;
    }
//    结束生命周期，在服务器关闭时候执行destroy方法
    @Override
    public void destroy() {
    }
}

package com.company;
import javax.servlet.*;
import java.io.IOException;
public class ServletDemo implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
    }
    @Override
    public ServletConfig getServletConfig() {
        return null;
    }
    //  使用service服务的方法，其他暂时不用管
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("Hello Servlet");
        System.out.println("Test");
    }
    @Override
    public String getServletInfo() {
        return null;
    }
    @Override
    public void destroy() {
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
<!--配置-->
    <display-name>HelloServlet</display-name>
<!--    servlet声明-->
    <servlet>
<!--        随便创建想要的Servlet名字-->
        <servlet-name> ServletDemo </servlet-name>
<!--        找到servlet对应的类，输入 包.具体类名-->
        <servlet-class> com.company.ServletDemo </servlet-class>
    </servlet>
<!--    servlet访问方式的声明-->
    <servlet-mapping>
<!--        映射Servlet名-->
        <servlet-name>ServletDemo</servlet-name>
<!--        映射路径配置一般就用 "/"+映射类名-->
        <url-pattern>/ServletDemo</url-pattern>
    </servlet-mapping>
</web-app>

package com.company;
import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
public class GenServlet extends GenericServlet {
//    除了service方法其他都不需要覆写
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("我是service方法");
//        判断请求方式
        String method = servletRequest.getMethod();
        if (method.equals("GET")){
        }else if (method.equals("POST")){
        }
    }
}

package com.company;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
//多路径设置
@WebServlet({"/Hello","/Dome","/kimi"})
public class HttpServlet extends javax.servlet.http.HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("GET!!!!!!!!!");
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("POST!!!!!!!!!!!!");
    }
}

GET /index.html HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36
Accept-Language: en-US,en;q=0.9

HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 1234
Cache-Control: max-age=3600
<!DOCTYPE html>
<html>
<head>
  <title>Welcome</title>
</head>
<body>
  <h1>Hello, World!</h1>
  <p>This is a sample HTML page.</p>
</body>
</html>