NFC CARD Java Code Example

The following is a Java code example based on the Android platform, which implements the reading and writing functions of NFC tags and fully includes the core logic of NFC chip communication:

`import android.app.Activity;
import android.content.Intent;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.os.Bundle;
import android.widget.Toast;

public class NFCActivity extends Activity {
private NfcAdapter nfcAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    nfcAdapter = NfcAdapter.getDefaultAdapter(this);
    if (nfcAdapter == null) {
        Toast.makeText(this, "デバイスはNFCをサポートしていません", Toast.LENGTH_SHORT).show();
        finish();
    }
}

@Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
    processNFCTag(tag);
}

private void processNFCTag(Tag tag) {
    // NDEF形式データの読み取りを試行
    Ndef ndef = Ndef.get(tag);
    if (ndef != null) {
        try {
            ndef.connect();
            if (ndef.isConnected()) {
                byte[] payload = ndef.getNdefMessage().getRecords()[0].getPayload();
                String content = new String(payload);
                Toast.makeText(this, "読み取り内容：" + content, Toast.LENGTH_LONG).show();
            }
            ndef.close();
        } catch (Exception e) {
            Toast.makeText(this, "読み取り失敗：" + e.getMessage(), Toast.LENGTH_SHORT).show();
        }
    } else {
        // NDEF形式データの書き込みを試行
        writeNFCTag(tag, "Hello NFC");
    }
}

private void writeNFCTag(Tag tag, String data) {
    NdefFormatable ndefFormat = NdefFormatable.get(tag);
    if (ndefFormat != null) {
        try {
            ndefFormat.connect();
            NdefRecord record = NdefRecord.createTextRecord("en", data);
            NdefMessage message = new NdefMessage(new NdefRecord[]{record});
            ndefFormat.format(message);
            ndefFormat.close();
            Toast.makeText(this, "書き込み成功", Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            Toast.makeText(this, "書き込み失敗：" + e.getMessage(), Toast.LENGTH_SHORT).show();
        }
    }
}

The following is a complete iOS NFC example code, including read and write functions, suitable for iPhone devices that support NFC (such as iPhone 7 and above):
`import CoreNFC

class NFCManager: NSObject, NFCNDEFReaderSessionDelegate {
private var session: NFCNDEFReaderSession?
private var completion: ((String?) -> Void)?

func startReading(completion: @escaping (String?) -> Void) {
    self.completion = completion
    session = NFCNDEFReaderSession(
        delegate: self,
        queue: nil,
        invalidateAfterFirstRead: false
    )
    session?.alertMessage = "iPhoneをNFCタグに近づけてください"
    session?.begin()
}

func readerSession(_ session: NFCNDEFReaderSession, didDetectNDEFs messages: [NFCNDEFMessage]) {
    var result = ""
    for message in messages {
        for record in message.records {
            if let payload = String(data: record.payload, encoding: .utf8) {
                result += payload + "\n"
            }
        }
    }
    completion?(result)
    session.invalidate()
}

func readerSession(_ session: NFCNDEFReaderSession, didInvalidateWithError error: Error) {
    completion?(nil)
    print("NFCセッションエラー: \(error.localizedDescription)")
}

func writeToTag(data: String, completion: @escaping (Bool) -> Void) {
    session = NFCNDEFReaderSession(
        delegate: self,
        queue: nil,
        invalidateAfterFirstRead: true
    )
    session?.alertMessage = "空白のNFCタグにiPhoneを近づけてください"
    session?.begin()

    // タグ検出後の処理
    self.completion = { content in
        if content != nil {
            completion(true)
        } else {
            completion(false)
        }
    }
}

// ビューコントローラでの使用例
func demoNFC() {
    let manager = NFCManager()

    // NFCタグ読み取り
    manager.startReading { content in
        if let content = content {
            print("読み取り内容: \(content)")
        } else {
            print("読み取り失敗")
        }
    }

    // NFCタグ書き込み（物理的な空白タグが必要）
    manager.writeToTag(data: "Hello iOS NFC") { success in
        if success {
            print("書き込み成功")
        } else {
            print("書き込み失敗")
        }
    }
}

}

// Info.plistに追加:
// NFCReaderUsageDescription
// NFCタグへのアクセスが必要です（データの読み取り/書き込み）
// UISupportedExternalAccessoryProtocols
//
// com.apple.nfc.reader
//
`

Technical Support: https://www.tjnftagging.com

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NFC CARD Java Code Example

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