Android Wi-Fi Scan: Filter printers from ScanResult

Android Wi-Fi Scan: Filter Printers from ScanResult

This article delves into the process of filtering printers from Wi-Fi scan results on Android devices. We will explore the essential techniques and code examples to achieve this functionality.

Understanding the ScanResult

The `ScanResult` object in Android’s Wi-Fi framework provides information about detected Wi-Fi networks. It includes details like:

• SSID (Service Set Identifier)
• BSSID (Basic Service Set Identifier)
• Signal Strength
• Capabilities (e.g., security type)

Identifying Printers

Printers often appear on Wi-Fi scans as access points, but they typically have specific characteristics that distinguish them from other devices. Some common indicators include:

• SSID: Often contains the printer model name or manufacturer name (e.g., “HP-LaserJet-P1102w”).
• BSSID: May follow a particular pattern or prefix associated with printer manufacturers.
• Capabilities: Printers might advertise specific services or capabilities, such as printing or network management.

Filtering Techniques

To filter printers from `ScanResult` data, you can employ various techniques:

1. SSID Pattern Matching

This method involves searching for specific keywords or patterns in the SSID. You can use regular expressions or string comparisons to identify printer-related names.

Code Example

import android.net.wifi.ScanResult;

// ...

for (ScanResult result : results) {
  String ssid = result.SSID;
  if (ssid.contains("HP") || ssid.contains("Canon") || ssid.contains("Epson")) {
    // This ScanResult likely represents a printer
    // ...
  }
}

2. BSSID Prefix Matching

Certain printer manufacturers or models might have identifiable prefixes in their BSSID. You can filter based on these prefixes.

Code Example

import android.net.wifi.ScanResult;

// ...

for (ScanResult result : results) {
  String bssid = result.BSSID;
  if (bssid.startsWith("00:14:22")) { // Example prefix for HP printers
    // This ScanResult likely represents a printer
    // ...
  }
}

3. Wi-Fi Service Discovery

Some printers support Bonjour (mDNS) service discovery. You can leverage this mechanism to detect and filter printer devices.

Code Example

// Using Bonjour (mDNS) service discovery

// ...

for (ServiceInfo service : serviceInfos) {
  if (service.getType().equals("_printer._tcp.local.")) {
    // This service likely represents a printer
    // ...
  }
}

Considerations

Keep in mind that filtering techniques are not always perfect. There might be cases where non-printers exhibit similar characteristics or printers don’t adhere to common conventions.

Conclusion

Filtering printers from Wi-Fi scan results on Android can be achieved using various approaches. The most effective technique often depends on the specific requirements and the printer models you are targeting. By combining pattern matching, BSSID analysis, and service discovery, you can enhance the accuracy of printer identification and streamline your application’s functionality.