Enterprise Application: File Upload in C#, Java, and Golang

Below are examples of a basic file upload functionality for both images and PDF files in C#, Java, and Golang. In these examples, I’ll assume a simple console-based application, and in a real-world scenario, you would integrate this with a web application and handle file uploads through a web form.

C# Image and PDF File Upload:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        Console.WriteLine("Enter file path (image or PDF):");
        string filePath = Console.ReadLine();

        if (File.Exists(filePath))
        {
            string fileType = Path.GetExtension(filePath).ToLower();

            if (fileType == ".jpg" || fileType == ".png" || fileType == ".pdf")
            {
                Console.WriteLine("File uploaded successfully in C#.");
            }
            else
            {
                Console.WriteLine("Invalid file type. Only JPG, PNG, and PDF are allowed.");
            }
        }
        else
        {
            Console.WriteLine("File not found.");
        }
    }
}

Java Image and PDF File Upload:

import java.util.Scanner;
import java.io.File;

public class FileUploadExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter file path (image or PDF):");
        String filePath = scanner.nextLine();

        File file = new File(filePath);

        if (file.exists()) {
            String fileType = getFileExtension(file);

            if (fileType.equals("jpg") || fileType.equals("png") || fileType.equals("pdf")) {
                System.out.println("File uploaded successfully in Java.");
            } else {
                System.out.println("Invalid file type. Only JPG, PNG, and PDF are allowed.");
            }
        } else {
            System.out.println("File not found.");
        }
    }

    static String getFileExtension(File file) {
        String name = file.getName();
        int lastIndexOfDot = name.lastIndexOf(".");
        return (lastIndexOfDot == -1) ? "" : name.substring(lastIndexOfDot + 1);
    }
}

Golang (Go) Image and PDF File Upload:

package main

import (
    "fmt"
    "path/filepath"
)

func main() {
    fmt.Println("Enter file path (image or PDF):")
    var filePath string
    fmt.Scanln(&filePath)

    if fileExists(filePath) {
        fileType := getFileExtension(filePath)

        if fileType == "jpg" || fileType == "png" || fileType == "pdf" {
            fmt.Println("File uploaded successfully in Golang.")
        } else {
            fmt.Println("Invalid file type. Only JPG, PNG, and PDF are allowed.")
        }
    } else {
        fmt.Println("File not found.")
    }
}

func fileExists(filePath string) bool {
    _, err := filepath.Abs(filePath)
    return err == nil
}

func getFileExtension(filePath string) string {
    ext := filepath.Ext(filePath)
    return ext[1:]
}

These examples demonstrate a basic file upload check for images (JPG and PNG) and PDF files in C#, Java, and Golang. In a web application, you would typically handle file uploads through a form, validate file types, and store them securely. Ensure that you handle user-uploaded files with caution to prevent security vulnerabilities.