如何在JDBC中从存储过程中获取输出

import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Types;

public class JdbcExample {
    public static void main(String[] args) {
        try {
            // 1. 创建Connection对象
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "username", "password");

            // 2. 创建CallableStatement对象
            CallableStatement cstmt = conn.prepareCall("{call my_stored_procedure(?, ?)}");

            // 3. 注册输出参数
            cstmt.registerOutParameter(2, Types.INTEGER);

            // 4. 执行存储过程
            cstmt.execute();

            // 5. 获取输出参数的值
            int outputValue = cstmt.getInt(2);
            System.out.println("Output value: " + outputValue);

            // 关闭连接和Statement对象
            cstmt.close();
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}