「www.baidu.com:443」模拟登入页面

www.baidu.com:443

今天我们学习了模拟一个登入页面。

首先：打开sql，创建一个表tb_user,具体参数如下：

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接着：创建几个包，包里创建几个文件，截图如下

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Music、DBUtil和Test1是上节课的，我们忽略就好。

MusicDao中输入代码：

package com.zhongruan.Dao;

import com.didi.model.Music;

import com.zhongruan.Util.DBUtil;

import java.sql.Connection;

import java.sql.Preparedstatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.List;

public class MusicDao {

public static List<Music> findMusics(){
    ResultSet resultSet = null;
    PreparedStatement statement = null;
    Connection connection = null;
    List<Music> musics=new ArrayList<>();
    try {
        connection = DBUtil.getConnection();
        String sql = "select * from music";
        statement = connection.preparestatement(sql);
        resultSet = statement.executequery();
        while (resultSet.next()) {
            Music music = new Music();
            music.setId(resultSet.getInt(1));
            music.setName(resultSet.getString(2));
            music.setAuthor(resultSet.getString(3));
            musics.add(music);
        }
    } catch (Exception e) {
        e.printstacktrace();
    } finally {
        DBUtil.closeAll(resultSet, statement, connection);
    }
    return musics;

}
public static void delete(int id) throws SQLException{
    Connection connection= DBUtil.getConnection();
    String sql="delete from music where id=?";
    PreparedStatement statement=connection.prepareStatement(sql);
    statement.setInt(1,id);
    statement.executeUpdate();
    DBUtil.closeAll(null,statement,connection);
}
public static void charu(String name, String author) throws SQLException {
    Connection connection=DBUtil.getConnection();
    String sql="insert into music(name,author) values(?,?)";
    PreparedStatement statement=connection.prepareStatement(sql);
    statement.setString(1,name);
    statement.setString(2,author);
    statement.executeUpdate();
    DBUtil.closeAll(null,statement,connection);
}



public static void  updateMusic(int id,String newname) throws SQLException{
    Connection connection=DBUtil.getConnection();
    String sql="update music set name=? where id=?";
    PreparedStatement statement=connection.prepareStatement(sql);
    statement.setString(1,newname);
    statement.setInt(2,id);
    statement.executeUpdate();
    DBUtil.closeAll(null,statement,connection);
}

}

在UserDao中输入代码：

package com.zhongruan.Dao;

import com.zhongruan.Util.DBUtil;

import com.zhongruan.model.User;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.util.List;

public class UserDao {

public static User findUserByUsername(String username){

ResultSet resultSet=null;

PreparedStatement statement=null;

Connection connection=null;

User user=null;

try{

connection= DBUtil.getConnection();

String sql=“select * from tb_user where username=?”;

statement=connection.prepareStatement(sql);

statement.setString(1,username);

resultSet=statement.executeQuery();

while (resultSet.next()){

user=new User();

user.setUsername(resultSet.getString(2));

user.setPassword(resultSet.getString(3));

}

}catch (Exception e){

e.printStackTrace();

}finally {

DBUtil.closeAll(resultSet,statement,connection);

}

return user;

}

public void churu(String username,String passwod){

ResultSet resultSet=null;

PreparedStatement statement=null;

Connection connection=null;

try {

connection=DBUtil.getConnection();

String sql=“insert into tb_user(username,password) values(?,?)”;

statement=connection.prepareStatement(sql);

statement.setString(1,username);

statement.setString(2,passwod);

statement.executeUpdate();

}catch (Exception e){

e.printStackTrace();

}finally {

DBUtil.closeAll(resultSet,statement,connection);

}

在LoginException输入代码：

package com.zhongruan.exception;

public class LoginException extends Exception{

public LoginException(String message){

super(message);

}

在User中输入代码：

package com.zhongruan.model;

public class User {

private String username;

private String password;

private int type;

public int getType() {

return type;

}

public void setType(integer type) {
    this.type = type;
}



public String getUsername() {
    return username;
}

@Override
public String toString() {
    return "User{" +
            "username='" + username + '\'' +
            ", password='" + password + '\'' +
            ", type=" + type +
            '}';
}

public void setUsername(String username) {
    this.username = username;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

}

在View中输入代码：

package com.zhongruan.Util;

import com.didi.model.Music;

import com.zhongruan.Dao.MusicDao;

import com.zhongruan.Dao.UserDao;

import com.zhongruan.exception.LoginException;

import com.zhongruan.model.User;

import org.omg.CORBA.PUBLIC_MEMBER;

import java.sql.SQLException;

import java.util.List;

import java.util.scanner;

public class View {

public static void main(String[] args) throws LoginException, SQLException {

boolean flag = true;

while (flag) {

Scanner input = new Scanner(System.in);

System.out.println(“请输入用户名”);

String username = input.next();

System.out.println(“请输入密码”);

String passwod = input.next();

        UserDao userDao = new UserDao();
        User user = UserDao.findUserByUsername(username);
        if (user == null) {
            System.out.println("---该用户尚未注册。请先注册---");
            System.out.println("请输入注册名");
            String name = input.next();
            System.out.println("请输入注册码");
            String pw = input.next();
            userDao.churu(name, pw);

        } else if (user.getPassword().equals(passwod)) {
            System.out.println("---欢迎来到音乐管理系统---");
            musicSystem();
            flag=false;
        } else {
            //System.out.println("---密码输入错误，请重新输入");
            throw new LoginException("登入失败");

        }
    }
}
public static void musicSystem() throws SQLException {
    Scanner input=new Scanner(System.in);
    System.out.println("1.音乐查询 2.音乐添加 3.音乐修改 4.音乐删除 5退出");
    int choice=input.nextint();
    switch (choice){
        case 1:
            //1.音乐查询
            List<Music> musics=MusicDao.findMusics();
            System.out.println(musics);
            break;
        case 2:
            System.out.println("请输入要输入的音乐名");
            String ym=input.next();
            System.out.println("请输入插入的作者名");
            String au=input.next();
            MusicDao.charu(ym,au);
            break;
        case 3:
            System.out.println("请输入要删除的id");
            int id=input.nextInt();
            MusicDao.delete(id);
        case 4:
            System.out.println("请输入要修改的 id");
            int id1=input.nextInt();
            System.out.println("请输入新的音乐名");
            String newym=input.next();
            System.out.println("请输入新的作者名");
            String newau=input.next();
            MusicDao.updateMusic(id1,newym,newau);
            break;
        case 5:
            System.exit(0);

    }

}

}

代码到这个步骤就已经写完了，接下来在View中运行，看一下结果怎么样。

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