\\簡單java連線mysql例子：
public class MySqlDemo {

    private static final String USER = "root";
    private static final String PASSWORD = "root";
    private static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
    private static final String DB_URL = "jdbc:mysql://localhost:3306/test?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC";


    public static void main(String[] args) {
        Connection conn = null;
        Statement stm = null;
        try{
            // 註冊 JDBC 驅動
            Class.forName(JDBC_DRIVER);

            // 開啟連結
            System.out.println("連線資料庫...");
            conn = DriverManager.getConnection(DB_URL,USER,PASSWORD);

            // 執行查詢
            System.out.println(" 例項化Statement物件...");
            stm = conn.createStatement();
            String sql;
            sql = "SELECT id, name, age FROM user";
            ResultSet rs = stm.executeQuery(sql);

            while(rs.next()){
                // 通過欄位檢索
                int id  = rs.getInt("id");
                String name = rs.getString("name");
                String age = rs.getString("age");

                System.out.println(String.format("id=%s,name=%s,age=%s",id,name,age));
            }
            // 完成後關閉
            rs.close();
            stm.close();
            conn.close();
        }catch(SQLException se){
            // 處理 JDBC 錯誤
            se.printStackTrace();
        }catch(Exception e){
            // 處理 Class.forName 錯誤
            e.printStackTrace();
        }finally{
            // 關閉資源
            try{
                if(stm!=null){
                    stm.close();
                }
            }catch(SQLException se2){
            }// 什麼都不做
            try{
                if(conn!=null){
                    conn.close();
                }
            }catch(SQLException se){
                se.printStackTrace();
            }
        }
        System.out.println("end!");
    }
}