java项目实践-tomcat实现用户登录-day17

标签：java tomcat request System day17 println import servlet javax

1. 安装
2. 初识tomcat
2. 创建tomcat项目
3. 启动之前
3. java jsp
4. Request Response对象的其他属性
5. 用户登录小功能

1. 安装

tomcat.apache.org
下载链接：https://tomcat.apache.org/download-80.cgi

2. 初识tomcat

bin
start.bat -->localhost:8080 （JDK依赖）
shutdowm.bat
conf
server.xml --8080默认值
lib 目录jar包
jsp.jar 重要
serverlet.jar 重要
webapps目录
web项目打成war包

运行startup.bat 并在浏览器中访问 localhost:8080

说明已经能正常使用

2. 创建tomcat项目

new project
注意 javaEE 需要勾选 web application

new Class MyServlet

导包

继承HttpServlet 并重写方法

package com.msb;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 11:34
 * @Description: com.msb
 * @version: 1.0
 */
public class MyServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().write("my first web project");
        System.out.println("my first web project");
    }
}

web.xml定义

<?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">


    <servlet>
        <servlet-name>mysevlet</servlet-name>
        <servlet-class>com.msb.MyServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>mysevlet</servlet-name>
        <url-pattern>/first</url-pattern>
    </servlet-mapping>
</web-app>

3. 启动之前

-->

启动webserver

package com.msb;

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;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 15:03
 * @Description: ${PACKAGE_NAME}
 * @version: 1.0
 */
@WebServlet(name = "MyServlet2")
public class MyServlet2 extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().write("second hehe !");
    }
}

web.xml文件配置增加

    <servlet>
        <servlet-name>mysevlet2</servlet-name>
        <servlet-class>com.msb.MyServlet2</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>mysevlet2</servlet-name>
        <url-pattern>/second</url-pattern>
    </servlet-mapping>

再访问
http://localhost:8080/firstweb/second

创建servles实例
调用init()方法
调用service方法
输出相应
调用destory方法

web.xml其他配置
load-on-startup 1 启动tomcat的时候就会创建serverlet对象 1表示优先级

3. java jsp

增加method.jsp并访问

<%--
  Created by IntelliJ IDEA.
  User: chenw
  Date: 2023/10/15
  Time: 15:28
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <form action="/firstweb/method", method="post">
        用户名：<input   type="text"  name="username"   value=""   /><br/>
        密码：<input     type="text"   name="password"  value="" /><br/>
        <input type="submit", value="登录">

    </form>

</body>
</html>

http://localhost:8080/firstweb/method.jsp

package com.msb;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 15:22
 * @Description: ${PACKAGE_NAME}
 * @version: 1.0
 */
public class MethodServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("/method post");
        response.getWriter().write("hello");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("/method get");

    }
}

4. Request Response对象的其他属性

package com.msb;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sound.midi.Soundbank;
import java.io.IOException;
import java.net.URI;
import java.util.Enumeration;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 15:56
 * @Description: ${PACKAGE_NAME}
 * @version: 1.0
 */
public class TestRequestServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("test request post 请求");
        String name = request.getParameter("name");
        String pwd = request.getParameter("pwd");
        System.out.println("name:"+name);
        System.out.println("pwd:"+pwd);

        String remoteAddr = request.getRemoteAddr();
        System.out.println("remoteAddr:"+remoteAddr);

        String remoteHost = request.getRemoteHost();
        System.out.println("remoteHost:"+remoteHost);

        int remotePort = request.getRemotePort();
        System.out.println("remotePort:"+remotePort);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("test request get 请求");

        String method = request.getMethod();
        System.out.println("method： "+method);

        String requestURI = request.getRequestURI();
        System.out.println("uri:" + requestURI);

        StringBuffer requestURL = request.getRequestURL();
        System.out.println("url:"+requestURL);

        //协议
        String scheme = request.getScheme();
        System.out.println("schema:"+scheme);


        // 请求头 User-Agent的value
        String ua = request.getHeader("Yser-Agent");
        System.out.println("ua:"+ua);

        Enumeration<String> headerNames = request.getHeaderNames();// 所有header key
        while (headerNames.hasMoreElements()){
            String s = headerNames.nextElement();
            String header = request.getHeader(s);
            System.out.println("key:"+s);
            System.out.println("header:"+ header);
        }

        response.getWriter().write("hello");

    }
}

5. 用户登录小功能

用户登录流程：

用户GET请求返回原生的页面
客户端填写相应的数据发起POST请求
服务端逻辑校验处理
服务端返回处理的结果

导包：
setting--project struture--module--jar
添加 tomcat安装位置lib下面的servlet_api.jar

package com.msb;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 19:52
 * @Description: ${PACKAGE_NAME}
 * @version: 1.0
 */
public class PageServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("Post method");
        response.getWriter().write("welcome !");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("get method !!!!");
        response.setContentType("text/html");

        PrintWriter writer = response.getWriter();
        writer.write("<html>");
        writer.write("<header>");
        writer.write("</header>");
        writer.write("<body>");
        writer.write("<form action='/user/login', method='post'>");

        writer.write("username:<input type='login' name='name' value=''></br>");
        writer.write("password:<input type='login' name='pwd' value=''></br>");
        writer.write("<input type='submit'  value='login'>");

        writer.write("</form>");
        writer.write("</body>");
        writer.write("</html>");
    }
}

<?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">
    <servlet>
        <servlet-name>PageServlet</servlet-name>
        <servlet-class>com.msb.PageServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>PageServlet</servlet-name>
        <url-pattern>/login</url-pattern>
    </servlet-mapping>

</web-app>

mysql for java驱动下载地址：
https://downloads.mysql.com/archives/c-j/

数据库：

项目结构：

LoginServlet

package com.msb.control;

import com.msb.entity.User;
import com.msb.service.UserService;
import com.msb.service.impl.UserServiceImpl;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 20:29
 * @Description: ${PACKAGE_NAME}
 * @version: 1.0
 */
public class LoginServlet extends HttpServlet {

    UserService userService = new UserServiceImpl();

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("post method !");
        String name = request.getParameter("name");
        String pwd= request.getParameter("pwd");

        User user = new User(name, pwd);
        User u = null;
        try {
            u = userService.checkUser(user);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        if (u!=null){
            response.getWriter().write("welcome:" + u.getName());
        }else{
            System.out.println(403);
            response.setStatus(403, "not permitted");
        }


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

UserDaoImpl

package com.msb.dao.impl;

import com.msb.dao.UserDao;
import com.msb.entity.User;

import java.sql.*;
import java.util.Map;

/**
 * @Auther: jack.chen
 * @Date: 2023/10/15 - 10 - 15 - 20:28
 * @Description: com.msb.dao.impl
 * @version: 1.0
 */
public class UserDaoImpl implements UserDao {
    @Override
    public User checkUser(User user) throws ClassNotFoundException, SQLException {
        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        User u = null;

//        System.out.println("user:" + user.toString());

        // 加载包
        Class.forName("com.mysql.cj.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/jackdb", "root", "");

        pstmt = conn.prepareStatement("select * from `user` where username = ? and pwd =?");

        pstmt.setString(1, user.getName());
        pstmt.setString(2, user.getPwd());

        rs = pstmt.executeQuery();
        while (rs.next()){
            u = new User(rs.getInt("id"), rs.getString("username"), rs.getString("pwd"));
        }
        return u;
    }

}

调用路径：
control --> service --> dao

终于搞定：

经验：

mysql java驱动
navicate 的使用
mysql的使用

标签：java,tomcat,request,System,day17,println,import,servlet,javax
From： https://www.cnblogs.com/cavalier-chen/p/17766377.html