本文共 4063 字，大约阅读时间需要 13 分钟。

JDBC???????

1. ????

JDBC?Java DataBase Connectivity??Java????????????????????????????????????????????JDBC?Java??????? JDBC ???????????MySQL?Oracle?PostgreSQL??

JDBC?????

JDBC ?????????

JDBC ???????????????????????

2. JDBC ?????

?? JDBC ?????????????????

3. ?????????

????? JDBC ????????????

1. MySQL??????

• ?????????MySQL???????? mysql-connector-java-8.0.16.jar ?????? lib ???????????????

  Class.forName("com.mysql.cj.jdbc.Driver");

2. ????

• ??????????? URL ??????? &serverTimezone=UTC????

  String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";

3. SQL????

• ??????? PreparedStatement ?? Statement??????? SQL ???

  PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM table WHERE username=? AND password=?");
  preparedStatement.setString(1, username);
  preparedStatement.setString(2, password);

4. JDBC????

???????? JDBC ????????

package com.lut.test;
import java.sql.*;
public class Test {
    public static void main(String[] args) {
        try {
            // ????
            Class.forName("com.mysql.cj.jdbc.Driver");
            
            // ???????
            String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
            String username = "root";
            String password = "123456";
            
            // ????
            Connection connection = DriverManager.getConnection(url, username, password);
            
            // ????
            String sql = "SELECT * FROM table";
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(sql);
            
            while (resultSet.next()) {
                String name = resultSet.getString("name");
                System.out.println(name + " - " + resultSet.getInt("id"));
            }
            
            System.out.println("????");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

????

5. PreparedStatement ???

??????? PreparedStatement ????????

package com.lut.test;
import java.sql.*;
public class Login {
    public static void main(String[] args) {
        try {
            // ????
            Class.forName("com.mysql.cj.jdbc.Driver");
            
            // ???????
            String url = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
            String username = "lisi";
            String password = "222";
            
            // ????
            Connection connection = DriverManager.getConnection(url, username, password);
            
            // ????
            String sql = "SELECT * FROM user WHERE username=? AND password=?";
            PreparedStatement preparedStatement = connection.prepareStatement(sql);
            
            // ????
            preparedStatement.setString(1, username);
            preparedStatement.setString(2, password);
            
            ResultSet resultSet = preparedStatement.executeQuery();
            
            if (resultSet.next()) {
                System.out.println("????");
            } else {
                System.out.println("????");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

6. ??

JDBC ? Java ???????????????????????????????????????????????????? PreparedStatement ??????????????????????????????????????