Java 中 NumberFoundException 的解析

Question

我是 Java 的新手，在解决 NumberFormatException. 时遇到问题我尝试运行的代码是

import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.lang.*;

public class NewClass {
    public static void main(String[] args)
    {
        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            String connectionUrl = "jdbc:mysql://localhost:3306" +
            "user=root&password=root";

            Connection con = DriverManager.getConnection(connectionUrl);
            Statement stmt = null;
            ResultSet rs = null;
            stmt = con.createStatement();
        }
        catch (SQLException e) {
            System.out.println("SQL Exception: "+ e.toString());
            } catch (ClassNotFoundException cE) {
            System.out.println("Class Not Found Exception: "+ cE.toString());
            }    
        catch(NumberFormatException ne)
        {
            System.out.println("NumberFormatException:"+ne.toString());
        }
    }

}

显示错误：

SQL Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Cannot load connection class because of underlying exception: 'java.lang.NumberFormatException: For input string: "3306user=root&password=root"'.

我该怎么办？

Answer 1

您的 connectionUrl 缺少 ? 以将端口与 queryString 分开：

String connectionUrl = "jdbc:mysql://localhost:3306?" +

Answer 2

那是因为你的连接 URL 不对，你至少应该有一个 ?在端口号之后。无论如何，最好使用此代码来获取连接：

String connectionUrl = "jdbc:mysql://localhost:3306";
Connection con = DriverManager.getConnection(connectionUrl, "root", "root" );

还记得在 finally 块中关闭连接、结果集和语句

Answer 3

像这样尝试

try{

            Class.forName("com.mysql.jdbc.Driver");
            con=DriverManager.getConnection("jdbc:mysql://localhost:3306/DB_NAME","root","root");   
        }
        catch(Exception e)
        {
            System.out.println("Error in connection"+e);
        }

Java 中 NumberFoundException 的解析

Resolution of NumberFoundException in Java

java

jdbc