package com.itheima.web;


import javax.servlet.*;
import java.io.IOException;
public class ServletDemo01 implements Servlet {

    @Override
    //服务方法: 处理请求的
    public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {
        System.out.println("hello world...");
    }


    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }



    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
		  http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
           version="2.5">

    <!--配置Servlet-->
    <servlet>
        <!--servlet-name: 名字 随便取; 一般就是类名-->
        <servlet-name>ServletDemo01</servlet-name>
        <!--servlet-class:Servlet这个类的全限定名-->
        <servlet-class>com.itheima.web.ServletDemo01</servlet-class>
    </servlet>
    <servlet-mapping>
        <!--servlet-name: 必须和servlet标签里面的servlet-name一样-->
        <servlet-name>ServletDemo01</servlet-name>
        <!--url-pattern: 配置访问的路径-->
        <url-pattern>/demo01</url-pattern>
    </servlet-mapping>

</web-app>

package com.itheima.web;

import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;
@WebServlet("/demo02")
public class ServletDemo02 implements Servlet{

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("hello world...");
    }


    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }



    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

package cn.itcast.web;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;

@WebServlet(name = "GenericDemoServlet",urlPatterns = "/generic")
public class GenericDemoServlet extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("GenericDemoServlet执行.......");
    }
}

/**
 * 包名:com.itheima.servlet
 *
 * @author Leevi
 * 日期2020-07-11  15:39
 * Servlet的常用的编写方法:
 * 1. 写一个类继承HttpServlet，重写doGet和doPost方法
 *    1.1 doGet()方法，是处理来自客户端的get请求
 *    1.2 doPost()方法，是处理来自客户端的post请求
 *
 *    通常情况下:服务器端针对同一个请求(不同的请求方式)不会做不同的处理,所以我们会选择在doGet中调用doPost
 * 2. 配置servlet的映射路径
 */
@WebServlet("/demo02")
public class ServletDemo02 extends HttpServlet{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("编写很多代码处理这次post请求");
    }
}

package com.itheima.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;

/**
 *
 * @author Leevi
 * 日期2020-07-11  15:59
 */
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 使用request获取请求参数
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        //2. 校验用户名和密码
        if ("jay".equals(username) && "123456".equals(password)) {
            //登录成功
            response.getWriter().write("login success");
        }else {
            //登录失败
            response.getWriter().write("login failed");
        }
    }
}

package com.itheima.servlet;

import javax.servlet.ServletContext;
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;

/**
- 包名:${PACKAGE_NAME}
*
- @author Leevi
  - 日期2020-07-11  16:11
  - 目标: 在ServletDemo02中获取servletDemo01中的一个变量的值
  - 1. 获取ServletContext对象:
  - getServletContext()
*/
@WebServlet("/demo01")
public class ServletDemo01 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
    @Override
   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = "周杰棍";
        //1. 获取ServletContext对象
        ServletContext servletContext = getServletContext();
        //2. 往容器ServletContext中存值
        servletContext.setAttribute("name",name);
    }
}

package com.itheima.servlet;

import javax.servlet.ServletContext;
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;
/**

- 包名:${PACKAGE_NAME}
*
- @author Leevi
- 日期2020-07-11  16:11
*/
@WebServlet("/demo02")
public class ServletDemo02 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 获取那个容器ServletContext
        ServletContext servletContext = getServletContext();
        //2. 从容器ServletContext中获取数据
        String name = (String) servletContext.getAttribute("name");

        System.out.println("在ServletDemo02中获取的name是:" + name);
    }
}  

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//根据文件名获得文件的mini类型
//1.获得ServletContext
//2.调用getMimeType()方法
String file01 = "a.mp3";
String file02 = "b.png";
String mimeType01 = getServletContext().getMimeType(file01);
String mimeType02 = getServletContext().getMimeType(file02);

response.getWriter().print("ServletDemo05..."+mimeType01+":"+mimeType02);

}

/**
 * 包名:${PACKAGE_NAME}
 * @author Leevi
 * 日期2020-07-11  16:41
 * 使用ServletContext获取web里面的资源文件的真实路径
 * 目标: 使用字节输入流，读取mm.jpg这张图片
 *     方法1: FileInputStream
 *     方法2: ClassLoader
 *     方法3: 使用ServletContext
 *
 * 在web项目中，将文件转换成流，有两种方式
 * 1. 如果文件在resources里面，使用类加载器
 * 2. 如果文件在web里面，使用ServletContext
 */
@WebServlet("/demo04")
public class ServletDemo04 extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //方法1: 使用FileInputStream,此时使用磁盘路径
        //InputStream is = new FileInputStream("C:/JavaEE_Relation/JavaEE98/itheima98_web/day24_servletcontext_03/web/mm.jpg");
        //方法2: 使用ClassLoader将文件转换成流
        //InputStream is = ServletDemo04.class.getClassLoader().getResourceAsStream("../../mm.jpg");

        //方法3: 使用ServletContext可以获取web里面的资源的真实路径
        ServletContext servletContext = getServletContext();
        //String realPath = servletContext.getRealPath("mm.jpg");

        InputStream is = servletContext.getResourceAsStream("mm.jpg");
        System.out.println(is);
    }
}

package com.itheima.servlet;

import javax.servlet.ServletContext;
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;

/**
 * 包名:${PACKAGE_NAME}
 *
 * @author Leevi
 * 日期2020-07-11  17:04
 * 每次接收到请求，则往容器中的计数器上面+1
 */
@WebServlet("/count")
public class CountServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 获取容器中计数器原本的次数
        ServletContext servletContext = getServletContext();
        Object count = servletContext.getAttribute("count");

        //判断ServletContext中是否有计数器
        if (count == null) {
            //说明当前是第一次访问
            //就往ServletContext中添加一个计数器
            servletContext.setAttribute("count",1);
        }else {
            //说明我不是第一次访问，那么就要对原来的计数器+1，再存进去
            int number = ((int) count) + 1;
            servletContext.setAttribute("count",number);
        }
        //2. 向客户端响应WelCome
        response.getWriter().write("WelCome!!!");
    }
}

package com.itheima.servlet;

import javax.servlet.ServletContext;
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;

/**
 * 包名:${PACKAGE_NAME}
 *
 * @author Leevi
 * 日期2020-07-11  17:04
 */
@WebServlet("/show")
public class ShowServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //从容器中获取计数器的值
        ServletContext servletContext = getServletContext();

        int count = (int) servletContext.getAttribute("count");

        //将count响应给客户端
        response.getWriter().print("access count is:"+count);
    }
}