2021.2.23---2.28--JavaEE1 项目管理机制笔记

学习内容》：

//========学习内容=========
Tomcat容器
Servlet初识
Servlet练习（1）
Servlet练习（导包+字符集）
Servlet练习（登录及查询）
Servlet练习（查询及存款）
Servlet管理机制（1）
Servlet管理机制（2）

《代码内容》：
主要思路—->做一个银行系统——使用MVC分层架构的思想，实现—登录，查询，存款，取款，转账功能。
//===================================================================================//

src—->
controller->
CunAndQuController

package controller;
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;
public class CunAndQuBalController extends HttpServlet {
    @Override
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        response.setCharacterEncoding("UTF-8");
        PrintWriter out = response.getWriter();
        out.write("<html>");
        out.write("<head>");
        out.write("<meta charset='UTF-8'>");
        out.write("</head>");
        out.write("<body>");
        out.write("<form action='docun' method='post'>");
        out.write("请"+uname+"输入存款金额<br>");
        out.write("<input type='text' name='bal' value><br>");
        out.write("<input type='submit' value='确认'>");
        out.write("<input type='hidden' name='uname' value="+uname+">");
        out.write("</form>");
        out.write("<form action='doqu' method='post'>");
        out.write("请"+uname+"输入取款金额<br>");
        out.write("<input type='text' name='bal' value><br>");
        out.write("<input type='submit' value='确认'>");
        out.write("<input type='hidden' name='uname' value="+uname+">");
        out.write("</form>");
        out.write("</body>");
        out.write("</html>");
    }
}

DoCunController

package controller;

import service.AtmService;
import util.MySpring;

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

public class DoCunController extends HttpServlet {

    private AtmService atmService = MySpring.getBean("service.AtmService");

    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        String cunbal = request.getParameter("bal");
        atmService.cun(uname,Float.parseFloat(cunbal));
    }
}

DoQuController

package controller;

import service.AtmService;
import util.MySpring;

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;

public class DoQuController extends HttpServlet {

    private static AtmService atmService = MySpring.getBean("service.AtmService");

    public void service(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        String bal = request.getParameter("bal");
        atmService.qu(uname,Float.parseFloat(bal));
    }

}

DoZhuanController

package controller;

import com.mysql.cj.protocol.a.MysqlBinaryValueDecoder;
import service.AtmService;
import util.MySpring;

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

public class DoZhuanController extends HttpServlet {

    private static AtmService atmService = MySpring.getBean("service.AtmService");

    @Override
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        String zhuanbal = request.getParameter("zhuanbal");
        String youname = request.getParameter("youname");
        //调用业务层转账方法
        atmService.zhuan(uname,youname,Float.parseFloat(zhuanbal));
    }
}

LoginController

package controller;

import service.AtmService;
import util.MySpring;

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;

public class LoginController extends HttpServlet {

    private static AtmService atmSevice = new AtmService();

    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        String upassword = request.getParameter("upassword");
        //调用业务层的登录业务方法
        String loginResult = atmSevice.login(uname,upassword);
        System.out.println(loginResult);
        response.setCharacterEncoding("UTF-8");
        PrintWriter out = response.getWriter();
        out.write("<html>");
        out.write("<head>");
        out.write("<meta charset=\"UTF-8\">");
        out.write("</head>");
        out.write("<body>");
        if ("登录成功".equals(loginResult)){
            out.write("********ATM银行系统********<br>");
            out.write("欢迎尊敬的"+uname+"！祝您心情愉快<br>");
            out.write("<a href=\"query?uname="+uname+"\">查询</a><br>");
            out.write("<a href=\"cunbal?uname="+uname+"\">存款</a><br>");
            out.write("<a href=\"qubal?uname="+uname+"\">取款</a><br>");
            out.write("<a href=\"zhuanbal?uname="+uname+"\">转账</a><br>");
            out.write("</body>");
            out.write("</html>");
        }else {
            out.write("用户名或密码错误");
            out.write("</body>");
            out.write("</html>");
        }
    }

}

QueryController

package controller;

import service.AtmService;
import util.MySpring;

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;

public class QueryController extends HttpServlet{

    private static AtmService atmService = MySpring.getBean("service.AtmService");

    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        Float ubal = atmService.query(uname);
        response.setCharacterEncoding("UTF-8");
        PrintWriter out = response.getWriter();
        out.write("<html>");
        out.write("<head>");
        out.write("<meta charset='UTF-8'>");
        out.write("</head>");
        out.write("<body>");
        out.write("尊敬的"+uname+"您的可用余额为："+ubal+" 感谢您的使用！");
        out.write("</body>");
        out.write("</html>");
    }

}

ViewZhuanBalController

package controller;

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;

@SuppressWarnings("all")
public class ViewZhuanBalController extends HttpServlet {

    @Override
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String uname = request.getParameter("uname");
        response.setCharacterEncoding("UTF-8");
        PrintWriter out = response.getWriter();
        out.write("<html>");
        out.write("<head>");
        out.write("<meta charset='UTF-8'>");
        out.write("</head>");
        out.write("<body>");
        out.write("<form action='dozhuan' method='post'>");
        out.write("请您输入要转账的用户<br>");
        out.write("<input type='text' name='youname' value=''><br>");
        out.write("请您输入要转账的金额<br>");
        out.write("<input type='text' name='zhuanbal' value=''><br>");
        out.write("<input type='submit' value='确认'>");
        out.write("<input type='hidden' name='uname' value="+uname+">");
        out.write("</form>");
        out.write("</body>");
        out.write("</html>");
    }
}

service—->
AtmService

package service;

import dao.AtmDao;
import domain.User;
import jdk.swing.interop.SwingInterOpUtils;
import util.MySpring;

public class AtmService {

    private static AtmDao atmDao = MySpring.getBean("dao.AtmDao");

    //登录
    public String login(String uname,String upassword){
        //调用daoc层从数据库中读取信息
        User user = atmDao.queryOne(uname);
        if (user != null && upassword.equals(user.getUpassword())){
            return "登录成功";
        }
        return "用户名或密码错误";
    }

    //查询余额
    public Float query(String name) {
         return atmDao.queryOne(name).getUbal();
    }

    //存款
    public void cun(String uname, Float cunbal) {
        User user = atmDao.queryOne(uname);
        user.setUbal(user.getUbal()+cunbal);
        //调用dao层更新对象
        atmDao.update(user);
        System.out.println("存款成功");
    }

    //存款
    public void qu(String uname, Float bal) {
        User user = atmDao.queryOne(uname);
        if (user.getUbal()>bal) {
            user.setUbal(user.getUbal() - bal);
            atmDao.update(user);
            System.out.println("取款成功");
        }else {
            System.out.println("余额不足");
        }
    }

    public void zhuan(String uname, String youname, Float zhuanBal) {
        User myselfUser = atmDao.queryOne(uname);
        User youselfUser = atmDao.queryOne(youname);
        if (myselfUser.getUbal() > zhuanBal && myselfUser != null && youselfUser != null){
            myselfUser.setUbal(myselfUser.getUbal() - zhuanBal);
            youselfUser.setUbal(youselfUser.getUbal() + zhuanBal);
            atmDao.update(myselfUser);
            atmDao.update(youselfUser);
        }else {
            System.out.println("余额不足");
        }
    }
}

dao—->
AtmDao

package dao;

import domain.User;

import java.sql.*;

@SuppressWarnings("all")
public class AtmDao {

    /**读取数据库中的一条记录**/
    public User queryOne(String uname){
        String driver = "com.mysql.cj.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/Atm?serverTimezone=CST&&characterEncoding=UTF-8";
        String userName = "root";
        String password = "at123123";
        String sql = "SELECT UNAME,UPASSWORD,UBAL FROM USER WHERE UNAME= ?";
        User user = null;
        try {
            Class.forName(driver);
            Connection conn = DriverManager.getConnection(url, userName, password);
            PreparedStatement pstat = conn.prepareStatement(sql);
            pstat.setString(1,uname);
            ResultSet resultSet = pstat.executeQuery();
            if (resultSet.next()){
                user = new User(resultSet.getString("UNAME"), resultSet.getString("UPASSWORD"), resultSet.getFloat("UBAL"));
                pstat.close();
                conn.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return user;
    }

    public void update(User user) {
        String driver = "com.mysql.cj.jdbc.Driver";
        String url = "jdbc:mysql://localhost:3306/Atm?serverTimezone=CST&&characterEncoding=UTF-8";
        String userName = "root";
        String password = "at123123";
        String sql = "UPDATE USER SET UPASSWORD=?,UBAL=? WHERE UNAME=?";
        try {
            Class.forName(driver);
            Connection conn = DriverManager.getConnection(url, userName, password);
            PreparedStatement pstat = conn.prepareStatement(sql);
            pstat.setString(1,user.getUpassword());
            pstat.setFloat(2,user.getUbal());
            pstat.setString(3,user.getUname());
            pstat.executeUpdate();
            pstat.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

domain—->
User

package domain;

public class User {

    private String Uname;
    private String Upassword;
    private Float Ubal;

    public User() {}

    public User(String uname, String upassword, Float ubal) {
        Uname = uname;
        Upassword = upassword;
        Ubal = ubal;
    }

    public String getUname() {
        return Uname;
    }

    public void setUname(String uname) {
        Uname = uname;
    }

    public String getUpassword() {
        return Upassword;
    }

    public void setUpassword(String upassword) {
        Upassword = upassword;
    }

    public Float getUbal() {
        return Ubal;
    }

    public void setUbal(Float ubal) {
        Ubal = ubal;
    }

    @Override
    public String toString() {
        return "User{" +
                "Uname='" + Uname + '\'' +
                ", Upassword='" + Upassword + '\'' +
                ", Ubal=" + Ubal +
                '}';
    }
}

web—>
index.html

<html lang="en">
<head>
    <meta charset="UTF-8">
</head>
<body>
        <form action="login" method="post">
            账号：<input type="text" name="uname" value=""><br>
            密码：<input type="password" name="upassword" value=""><br>
                 <input type="submit" value="登录">
        </form>

</body>
</html>

学习总结：
学懂的：
通过实战项目的练习，可以熟练掌握Servlet的开发，学习到了很多设计思想，例如单例设计模式—-生命周期托管。
Servlet的管理机制
默认的Servlet对象和我们之前封装的一样，是生命周期托管—-延迟加载的方式
如果想要修改为启动时立即加载，需要在web.xml中配置
中间填数字，数组越小加载的对象越快
继承HttpServlet中有三个父类方法可以重写
init()方法
destroy()方法
service()方法

========================================================
HttpServlet继承GenericServlet抽象类
GenericServlet实现了Servlet, Serv**letConfig, Serializable接口
HttpServlet中具体化了service方法，并且构成了方法重载

service(ServletRequest req,ServletResponse resp)其中这个方法是重写了GenericServlet抽象类中的方法，并强制转换成了HtppServletReq,Resp这两个对象
service(HttpServletRequest req,HttpServletResponse resp)这个方法中是一堆判断关于Http协议的请求名。

没学懂的：
没有
**

2021.2.23---2.28--JavaEE1 项目 管理机制 笔记