2020.12.16

一、今日学习内容

     今天练习了代码，增删改查

//Dao
package Dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;


import DBUtil.DBUtil;
import entity.Login;
import entity.User;

public class LoginDao {
    public boolean loginadd(Login login) {
        String sql = "insert into login(IDuser,password,flag) values('" + login.getIDuser() + "','" + login.getPassword() + "','" 
                     + login.getFlag() + "')";
        //创建数据库链接
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;

        try {
            state = conn.createStatement();
            state.executeUpdate(sql);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭连接
            DBUtil.close(state, conn);
        }

        if (a > 0) {
            f = true;
        }
        return f;
    }
    
    public boolean useradd(User user) {
        String sql = "insert into user(username,IDuser,password,userclass,usersex) values('" + user.getUsername()+"','"+user.getIDuser() + "','" + user.getPassword() + "','" 
                     + user.getUserclass() +"','"+user.getUsersex()+ "')";
        //创建数据库链接
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;

        try {
            state = conn.createStatement();
            state.executeUpdate(sql);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //关闭连接
            DBUtil.close(state, conn);
        }

        if (a > 0) {
            f = true;
        }
        return f;
    }
    
    public boolean loginjudge(String IDuser,String password) {
        String sql = "select * from user ";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        boolean f=false;
        
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                String iduser = rs.getString("IDuser");
                String pasw = rs.getString("password");
                if(iduser.equals(IDuser)&&pasw.equals(password)) {
                    f=true;   
            }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }        
        return f;
    }
    
    public List<User> chaxun(String username,String IDuser){
        String sql = "select * from user where ";
        if (username != "") {
            sql += "username like '%" +username+ "%'";
        }
        else if (IDuser != "") {
            sql += "IDuser like '%" +IDuser+ "%'";
        }
        List<User> list = new ArrayList<>();
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        User bean = null;
        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                String username1 = rs.getString("username");
                String IDuser1 = rs.getString("IDuser");
                String password1=rs.getString("password");
                String userclass1 = rs.getString("userclass");
                String usersex1=rs.getString("usersex");
                bean =new User(username1,IDuser1,password1,userclass1,usersex1);
                list.add(bean);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        return list;
    }
    
    public List<User> liulan() {
        String sql = "select * from user";
        List<User> list = new ArrayList<>();
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            User bean = null;
            while (rs.next()) {
                String username1 = rs.getString("username");
                String IDuser1 = rs.getString("IDuser");
                String password1=rs.getString("password");
                String userclass1 = rs.getString("userclass");
                String usersex1=rs.getString("usersex");
                bean =new User(username1,IDuser1,password1,userclass1,usersex1);
                list.add(bean);              
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        
        return list;
    }
    
    public boolean delete2(String username)
    {
        String sql="delete from user where username='" + username + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        int a = 0;
        boolean f = false;
        try {
            state = conn.createStatement();
            a=state.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(state, conn);
        }
        
        if (a > 0) {
            f = true;
        }
        return f;
    }
    
    public User getByname(String username) {
        String sql = "select * from user where username ='" + username + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        ResultSet rs = null;
        User user1 = null;

        try {
            state = conn.createStatement();
            rs = state.executeQuery(sql);
            while (rs.next()) {
                int id=rs.getInt("id");
                String IDuser1 = rs.getString("IDuser");
                String password1=rs.getString("password");
                String userclass1 = rs.getString("userclass");
                String usersex1=rs.getString("usersex");
                user1 = new User(id,username,IDuser1,password1,userclass1,usersex1);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs, state, conn);
        }
        return user1;
    }
    
    public boolean xiugai(User user) {
        String sql = "update user set username='" + user.getUsername() + "', IDuser='" + user.getIDuser() + "', password='" + user.getPassword()+ "', userclass='" + user.getUserclass()
        + "', usersex='" + user.getUsersex()+ "' where id='" + user.getId() + "'";
        Connection conn = DBUtil.getConn();
        Statement state = null;
        boolean f = false;
        int a = 0;

        try {
            state = conn.createStatement();
            a = state.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(state, conn);
        }

        if (a > 0) {
            f = true;
        }
        return f;
    }


}

//DBUtil
package DBUtil;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

/**
* 数据库连接工具
*
*/
public class DBUtil {

  public static String db_url = "jdbc:mysql://localhost:3306/test?serverTimezone=UTC";
  public static String db_user = "root";
  public static String db_pass = "08301016";

  public static Connection getConn() {
      Connection conn = null;

      try {
          Class.forName("com.mysql.cj.jdbc.Driver");//加载驱动
          conn = DriverManager.getConnection(db_url, db_user, db_pass);
      } catch (Exception e) {
          e.printStackTrace();
      }

      return conn;
  }

  /**
   * 关闭连接
   * @param state
   * @param conn
   */
  public static void close (Statement state, Connection conn) {
      if (state != null) {
          try {
              state.close();
          } catch (SQLException e) {
              e.printStackTrace();
          }
      }

      if (conn != null) {
          try {
              conn.close();
          } catch (SQLException e) {
              e.printStackTrace();
          }
      }
  }

  public static void close (ResultSet rs, Statement state, Connection conn) {
      if (rs != null) {
          try {
              rs.close();
          } catch (SQLException e) {
              e.printStackTrace();
          }
      }

      if (state != null) {
          try {
              state.close();
          } catch (SQLException e) {
              e.printStackTrace();
          }
      }

      if (conn != null) {
          try {
              conn.close();
          } catch (SQLException e) {
              e.printStackTrace();
          }
      }
  }
}

//entity.Login
package entity;

public class Login {
    private int id;
    private String IDuser;
    private String password;
    private String flag;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getIDuser() {
        return IDuser;
    }
    public void setIDuser(String iDuser) {
        IDuser = iDuser;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getFlag() {
        return flag;
    }
    public void setFlag(String flag) {
        this.flag = flag;
    }
    public Login(int id,String iDuser,String password,String flag) {
        this.id = id;
        IDuser = iDuser;
        this.password = password;
        this.flag = flag;
    }
    public Login(String iDuser,String password,String flag) {
        IDuser = iDuser;
        this.password = password;
        this.flag = flag;
    }

}

//entity.User
package entity;

public class User {
    private int id;
    private String username;
    private String IDuser;
    private String userclass;
    private String password;
    private String usersex;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getIDuser() {
        return IDuser;
    }
    public void setIDuser(String iDuser) {
        IDuser = iDuser;
    }
    public String getUserclass() {
        return userclass;
    }
    public void setUserclass(String userclass) {
        this.userclass = userclass;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getUsersex() {
        return usersex;
    }
    public void setUsersex(String usersex) {
        this.usersex = usersex;
    }
    public User(int id,String username,String iDuser,String password,String userclass,String usersex) {
        this.id = id;
        this.username = username;
        IDuser = iDuser;
        this.userclass = userclass;
        this.password = password;
        this.usersex = usersex;
    }
    public User(String username,String iDuser,String password,String userclass,String usersex) {
        this.username = username;
        IDuser = iDuser;
        this.userclass = userclass;
        this.password = password;
        this.usersex = usersex;
    }

}

//service
package Service;
import Dao.LoginDao;
import entity.Login;
import entity.User;
import java.util.List;

public class LoginService {
    
    LoginDao lDao=new LoginDao();
    
    public void loginadd(Login login) {
            lDao.loginadd(login);
    }
    
    public void useradd(User user) {
        lDao.useradd(user);
    }
    public boolean loginjudge(String IDuser,String password) {
        return lDao.loginjudge(IDuser, password);
    }
    public List<User> chaxun(String username,String IDuser) {
        return lDao.chaxun(username,IDuser);
    }
    public List<User> liulan() {
        return lDao.liulan();
    }
    public void delete2(String username) {
        lDao.delete2(username);
    }
    public User getByname(String username) {
        return lDao.getByname(username);
    }
    public void xiugai(User user) {
        lDao.xiugai(user);
    }

}

//servlet
package Servlet;
import java.util.Date; 
import java.text.SimpleDateFormat; 

import java.io.IOException;
import java.util.List;

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 entity.Login;
import entity.User;
import Service.LoginService;
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet{
    
    private static final long serialVersionUID = 1L;
    
    LoginService service=new LoginService();
    
     protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            req.setCharacterEncoding("utf-8");
            String method = req.getParameter("method");

            if ("loginadd".equals(method)) {
                loginadd(req, resp);
            } else if("useradd".equals(method)) {
                useradd(req,resp);
            }else if("chaxun".equals(method)) {
                chaxun(req,resp);
            }else if("liulan".equals(method)) {
                liulan(req,resp);
            }else if("delete2".equals(method)) {
                delete2(req,resp);
            }else if("getByname".equals(method)) {
                getByname(req,resp);
            }else if("getByname1".equals(method)) {
                getByname1(req,resp);
            }else if("xiugai".equals(method)) {
                xiugai(req,resp);
            }
     }
     
     private void loginadd(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
            req.setCharacterEncoding("utf-8");
            //获取数据
            String IDuser=req.getParameter("IDuser");
            String password=req.getParameter("password");
            String flag = req.getParameter("flag");
            Login login=new Login(IDuser,password,flag);
            
            service.loginadd(login);
            if(flag.equals("管理员")&&password.equals("123456")) {
                    req.setAttribute("message", "登录成功");
                    req.getRequestDispatcher("manager.jsp").forward(req,resp);
            }else if(flag.equals("管理员")&&!password.equals("123456")) {
                req.setAttribute("message", "密码错误，登录失败");
                req.getRequestDispatcher("login.jsp").forward(req,resp);
            }else if(flag.equals("读者")) {
                if(service.loginjudge(IDuser, password)) {
                    req.setAttribute("message", "登录成功");
                    req.getRequestDispatcher("login.jsp").forward(req,resp);
                }else {
                    req.setAttribute("message", "用户名或密码错误，登录失败");
                    req.getRequestDispatcher("login.jsp").forward(req,resp);
                }
            }
            
        }
     
     private void useradd(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
             req.setCharacterEncoding("utf-8");
            //获取数据
             String username=req.getParameter("username");
            String IDuser=req.getParameter("IDuser");
            String password=req.getParameter("password");
            String userclass=req.getParameter("userclass");
            String usersex=req.getParameter("usersex");
            User user=new User(username,IDuser,password,userclass,usersex);
            
            service.useradd(user);
            req.setAttribute("message", "录入成功");
            req.getRequestDispatcher("mareaadd.jsp").forward(req,resp);
     }
     
     private void chaxun(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
            req.setCharacterEncoding("utf-8");
            String username=req.getParameter("username");
            String IDuser = req.getParameter("IDuser");
            List<User> users = service.chaxun(username,IDuser);
            if(null==users||users.size()==0)
            {
                req.setAttribute("message", "没有该读者");
                req.getRequestDispatcher("chaxun.jsp").forward(req,resp);
            }
            else {
                req.setAttribute("users",users);
                req.getRequestDispatcher("list.jsp").forward(req,resp);
            }
        }
     private void liulan(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            req.setCharacterEncoding("utf-8");
            List<User> users = service.liulan();
            req.setAttribute("users",users);
            req.getRequestDispatcher("liulan.jsp").forward(req, resp);   
        }
     
     private void getByname(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         req.setCharacterEncoding("utf-8");
         String username = req.getParameter("username");
         User user1 = service.getByname(username);
         if(user1 == null) {
             req.setAttribute("message", "查无此信息！");
             req.getRequestDispatcher("delete2.jsp").forward(req,resp);
          } else {
             req.setAttribute("user1", user1);
             req.getRequestDispatcher("delete1.jsp").forward(req,resp);
          }
     }
     
     private void delete2(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         req.setCharacterEncoding("utf-8");
         String username=req.getParameter("username");
         service.delete2(username);
         req.setAttribute("message", "删除成功！");
         req.getRequestDispatcher("LoginServlet?method=liulan").forward(req,resp);
      }
     
     private void getByname1(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         req.setCharacterEncoding("utf-8");
         String username = req.getParameter("username");
         //System.out.println("***"+username);
         User user2 = service.getByname(username);
         if(user2 == null) {
             req.setAttribute("message", "查无此信息！");
             req.getRequestDispatcher("xiugai.jsp").forward(req,resp);
          } else {
             req.setAttribute("user2", user2);
             req.getRequestDispatcher("xiugai1.jsp").forward(req,resp);
          }
     }
     private void xiugai(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         req.setCharacterEncoding("utf-8");
         int id = Integer.parseInt(req.getParameter("id"));
         String username = req.getParameter("username");
         String IDuser= req.getParameter("IDuser");
         String password = req.getParameter("password");
         String userclass = req.getParameter("userclass");
         String usersex = req.getParameter("usersex");
         User user=new User(id,username,IDuser,password,userclass,usersex);

         service.xiugai(user);
         req.setAttribute("message", "修改成功");
         req.getRequestDispatcher("LoginServlet?method=liulan").forward(req,resp);
      }
}

二、遇到的问题

     用的还是不是很熟练

三、明日计划

   明天继续