java - 如何将数据库中的元素检索到 JDBC 程序中

Question

我尝试了一个基本程序来将数据从数据库表检索到java程序中。编译结束后，运行代码时出现异常。控制台中没有显示错误。显示异常消息

import java.sql.*;
public class class1 {
    public static void main(String args[]){
        String url = "jdbc:mysql://localhost:3306//orders";
        String username = "root";
        String password = "Luxan@22";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection(url, username, password);
            Statement st = con.createStatement();
            ResultSet rs =  st.executeQuery("SELECT CUST_NAME FROM CUSTOMERS");
            System.out.println("List of Registered customers: ");
            while(rs.next()){
                System.out.println(rs.getString("cust_name"));
            }
            st.close();
            con.close();
        }
        catch(Exception e){
            System.out.println("An Exception error occured while processing JDBC programme");
        }
    }
}

下面是我的控制台窗口中的输出

Fri Jan 17 19:34:24 IST 2020 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

An Exception error occured while processing JDBC programme

Answer 1

问题出在您的网址上。替换

"jdbc:mysql://localhost:3306//orders"

与

"jdbc:mysql://localhost:3306/orders"

请注意，我在 orders 之前删除了一个 /。