How to Determine the Size of a Web File Using Java's URLConnection?

How can I find the size of a web file using Java's URLConnection?

URLConnection urlConnection = new URL("http://example.com/file.txt").openConnection();
urlConnection.connect();
int fileSize = urlConnection.getContentLength();

In Java, you can determine the size of a web file by utilizing the `URLConnection` class. By establishing a connection to the desired URL, you can access metadata that includes the content length, which represents the size of the file in bytes.

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;

public class FileSizeChecker {
    public static void main(String[] args) {
        try {
            URL url = new URL("http://example.com/file.txt");
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("HEAD"); // Using HEAD to get headers only
            urlConnection.connect();

            int fileSize = urlConnection.getContentLength();
            System.out.println("File size: " + fileSize + " bytes");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Causes

• Improper handling of connection timeouts.
• Ignoring HTTP response codes that indicate errors.

Solutions

• Use `URLConnection` to open a connection to the file URL.
• Call the `connect()` method to establish the connection.
• Utilize the `getContentLength()` method to retrieve the file size.

Mistake: Using the `getContentLength()` method without calling `connect()` first.

Solution: Always ensure that the URL connection is established by calling `connect()` before trying to retrieve the content length.

Mistake: Neglecting to handle potential exceptions when opening a URL connection.

Solution: Implement proper error handling with try-catch to manage `IOException` and other potential issues.