IDEA中JDBC的完整构建

JDBC的基本流程与语句

JDBC（JavaDataBase Connectivity）就是Java数据库连接，说白了就是用Java语言来操作数据库。原来我们操作数据库是在控制台使用SQL语句来操作数据库，JDBC是用Java语言向数据库发送SQL语句。

JDBC连接数据库

数据库连接操作主要在BDutil文件中进行

    public class DButil {
        private static final String DRIVER_NAME = "com.mysql.jdbc.Driver";
        //数据库连接地址
        private static final String URL = "jdbc:mysql://localhost:3306/test?characterEncoding=utf8";
        //用户名
        private static final String USER_NAME = "root";
        //密码
        private static final String PASSWORD = "980526";
        public static Connection getConnection(){
            Connection connection=null;
            try{
                Class.forName(DRIVER_NAME);
                connection = DriverManager.getConnection(URL, USER_NAME, PASSWORD);
            }catch(Exception e){
                e.printStackTrace();
            }
            return connection;
        }
    
    
        public sta

tic void close(ResultSet resultSet) {
        if(resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public static void close(PreparedStatement statement) {

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

    }
    public static void close(Connection connection) {

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

bean包中Demo文件主要是对数据库表的构造

public class Demo {
    public Demo(String username, String password){
        this.username=username;
        this.password=password;
    }

    private int id;
    private String username;
    private String password;

    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 getPassword() {
        return password;
    }

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

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

DemoDao文件则是进行具体的增删改查操作

增加操作

public void insertUser(Demo newUser) {
    Connection connection = DButil.getConnection();
    PreparedStatement pstm = null;
    try {
        String sql = "insert into demo(id,username,password) values(?,?,?)";   //sql语言
        pstm = connection.prepareStatement(sql);

        //填充sql语句中的？
        pstm.setInt(1, newUser.getId());
        pstm.setString(2, newUser.getUsername());
        pstm.setString(3, newUser.getPassword());

        //使用executeUpdate函数执行sql语句
        pstm.executeUpdate();
        System.out.println("新增用户成功");
    }catch(Exception e){
        e.printStackTrace();
    }finally {
        DButil.close(pstm);
        DButil.close(connection);
    }
}

删除操作

  public void deleteUser(int id) {
    Connection connection = DButil.getConnection();
    PreparedStatement pstm = null;
    try {
        String sql = "delete from demo where id=?";
        pstm = connection.prepareStatement(sql);

        pstm.setInt(1,id);

        pstm.executeUpdate();
        System.out.println("删除用户成功");
    }catch(Exception e){
        e.printStackTrace();
    }finally {
        DButil.close(pstm);
        DButil.close(connection);
    }
}

修改操作

 public void updateUser(int modId, Demo modUser)  {
    Connection connection = DButil.getConnection();
    PreparedStatement pstm = null;
    try{
        String sql = "update demo set username=?,password=? where id=?";
        pstm = connection.prepareStatement(sql);

        pstm.setString(1, modUser.getUsername());
        pstm.setString(2, modUser.getPassword());
        pstm.setInt(3, modId);
        pstm.executeUpdate();

        System.out.println("修改用户成功");
    }catch(Exception e){
        e.printStackTrace();
    }finally {
        DButil.close(pstm);
        DButil.close(connection);
    }
}

查询操作

public static List findAll() {
        List list=new ArrayList<>();
    ResultSet resultSet=null;
    PreparedStatement statement=null;
    Connection connection=null;
    try {
        connection= DButil.getConnection();
        //3.写sql
        String sql="select * from demo";
        //4.得到statement对象
        statement = connection.prepareStatement(sql);
        //5.执行sql
        resultSet = statement.executeQuery();
        //6处理结果集
        while (resultSet.next()){
            int id=resultSet.getInt(1);
            String username=resultSet.getString(2);
            String password=resultSet.getString(3);
            Demo userInfo=new Demo(username,password);
            userInfo.setId(id);
            list.add(userInfo);
        }

    } catch (Exception e) {
        e.printStackTrace();
    }finally {
        DButil.close(resultSet);
        DButil.close(connection);
        DButil.close(statement);
    }
    return list;
    }

主函数模块调用

public static void main(String[] args) {
    System.out.println("请选择操作："+"\t"+"1、增加"+"\t"+"2、删除"+"\t"+"3、修改"+"\t"+"4、查询");
    while(true){
    Scanner sc=new Scanner(System.in);
    int k=sc.nextByte();
    switch (k){
        case 1:
            System.out.println("请输入："+"\t");
            DemoDao test1=new DemoDao();
            Scanner sc1 = new Scanner(System.in);
            int id1=sc1.nextByte();
            Scanner sc2 = new Scanner(System.in);
            String newNmae=sc2.next();
            Scanner sc3 = new Scanner(System.in);
            String newPassword=sc3.next();
            Demo newUser=new Demo(newNmae,newPassword);
            newUser.setId(id1);
            test1.insertUser(newUser);
            break;

        case 2:
            System.out.println("请输入："+"\t");
            DemoDao test2=new DemoDao();
            Scanner sc4 = new Scanner(System.in);
            int id2=sc4.nextByte();
            test2.deleteUser(id2);
            break;

        case 3:
            System.out.println("请输入："+"\t");
            DemoDao test3=new DemoDao();
            Scanner sc5 = new Scanner(System.in);
            int modId=sc5.nextByte();
            Scanner sc6 = new Scanner(System.in);
            String newNmae1=sc6.next();
            Scanner sc7 = new Scanner(System.in);
            String newPassword1=sc7.next();
            Demo modUser=new Demo(newNmae1,newPassword1);
            test3.updateUser(modId,modUser);
            break;

        case 4:
            DemoDao test4=new DemoDao();
            List list=new ArrayList<>();
            list=test4.findAll();
            System.out.println(list.toString());
            break;
    }}

}

至此，JDBC的连接以及基本操作都已完成