浅聊NFC

在项目中使用到nfc是,聊一聊NFC的试用范围

通过项目中遇到的各种坑,认识到使用nfc传输只能传输较小的内容

比如只能传输小于100k的内容

当nfc传输大于200k时,会出现文件过大异常

然后查询资料找到一般通过nfc传输文件都是通过Android Beam实现

在传输文件中NFC的功能是进行蓝牙或者wifi连接,然后使用蓝牙或者wifi进行传输文件

对于nfc传输,一般看的的都是传输一段字符串,进行校验

nfc传输速度较慢,一般为10k/s左右

项目中遇到只有nfc而无蓝牙的情况

做出了一个传输文件的nfcDemo

实现是将文件转为Byte[] 使用字节流传输文件

然后在接收端将流转为需要的文件的过程

代码写的很随意,请见谅!

项目代码

import android.app.Activity;import android.app.AlertDialog;import android.app.PendingIntent;import android.content.ContentResolver;import android.content.DialogInterface;import android.content.Intent;import android.content.IntentFilter;import android.content.IntentFilter.MalformedMimeTypeException;import android.content.res.Resources;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.Drawable;import android.net.Uri;import android.nfc.NdefMessage;import android.nfc.NdefRecord;import android.nfc.NfcAdapter;import android.nfc.Tag;import android.nfc.tech.Ndef;import android.nfc.tech.NdefFormatable;import android.os.Bundle;import android.os.Environment;import android.os.Parcelable;import android.provider.MediaStore;import android.text.Editable;import android.text.TextWatcher;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.Toast;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.text.SimpleDateFormat;import java.util.Date;public class MainActivity extends Activity {private static final String TAG = "stickynotes";private boolean mResumed = false;private boolean mWriteMode = false;NfcAdapter mNfcAdapter;private static final int REQUESTCODE_PICK = 0x2;// private static final int REQUESTCODE_CUTTING = 0x3;PendingIntent mNfcPendingIntent;IntentFilter[] mWriteTagFilters;IntentFilter[] mNdefExchangeFilters;private Button mNote;private String urlpath;private ImageView iv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);mNfcAdapter = NfcAdapter.getDefaultAdapter(this);findViewById(R.id.write_tag).setOnClickListener(mTagWriter);mNote = (Button) findViewById(R.id.note);iv = (ImageView) findViewById(R.id.iv);mNote.setOnClickListener(new onclick());// Handle all of our received NFC intents in this activity.mNfcPendingIntent = PendingIntent.getActivity(this, 0, new Intent(this,getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);// Intent filters for reading a note from a tag or exchanging over p2p.IntentFilter ndefDetected = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);try {ndefDetected.addDataType("text/plain");} catch (MalformedMimeTypeException e) {}mNdefExchangeFilters = new IntentFilter[] { ndefDetected };// Intent filters for writing to a tagIntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);mWriteTagFilters = new IntentFilter[] { tagDetected };}@Overrideprotected void onResume() {super.onResume();mResumed = true;// Sticky notes received from Androidif (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {NdefMessage[] messages = getNdefMessages(getIntent());byte[] payload = messages[0].getRecords()[0].getPayload();setNoteBody(payload);setIntent(new Intent()); // Consume this intent.}enableNdefExchangeMode();}@Overrideprotected void onPause() {super.onPause();mResumed = false;if (mNfcAdapter != null) {mNfcAdapter.disableForegroundNdefPush(this);}}@Overrideprotected void onNewIntent(Intent intent) {// NDEF exchange modeif (!mWriteMode&& NfcAdapter.ACTION_NDEF_DISCOVERED.equals(intent.getAction())) {NdefMessage[] msgs = getNdefMessages(intent);setNoteBody(msgs[0].getRecords()[0].getPayload());}// Tag writing modeif (mWriteMode&& NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())) {Tag detectedTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);writeTag(getNoteAsNdef(), detectedTag);}Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);ndef = Ndef.get(tag);Log.e("fzq", "-----------size " + ndef.getMaxSize());}/** * 选择图片 * @Description: TODO * @param * @return void * @throws * @author fzq * @date 2017-12-23 */public void selePic() {//Intent pickIntent = new Intent(Intent.ACTION_PICK, null);pickIntent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,"image/*");startActivityForResult(pickIntent, REQUESTCODE_PICK);if (mNfcAdapter == null) {mNfcAdapter = NfcAdapter.getDefaultAdapter(this);return;}mNfcAdapter.enableForegroundNdefPush(MainActivity.this, getNoteAsNdef());}/** * 文件转流 * @Description: TODO * @param @return * @return NdefMessage * @throws * @author fzq * @date 2017-12-23 */private NdefMessage getNoteAsNdef() {Bitmap bmp = null;if (postBitmap != null) {bmp = postBitmap;} else {Resources r = getResources();InputStream is = r.openRawResource(R.drawable.ic_launcher);BitmapDrawable bmpDraw = new BitmapDrawable(is);bmp = bmpDraw.getBitmap();}// bmp = BitMapUtils.getZoomImage(bmp, 100 * 1024);ByteArrayOutputStream baos = new ByteArrayOutputStream();bmp.compress(Bitmap.CompressFormat.JPEG, 100, baos);byte[] textBytes = baos.toByteArray();// byte[] textBytes = mNote.getText().toString().getBytes();Log.e("fzq", "------------textBytessize   " + textBytes.length);NdefRecord textRecord = new NdefRecord(NdefRecord.TNF_MIME_MEDIA,"text/plain".getBytes(), new byte[] {}, textBytes);return new NdefMessage(new NdefRecord[] { textRecord });}/** * 得到的数据流显示 * @Description: TODO * @param @param body * @return void * @throws * @author fzq * @date 2017-12-23 */private void setNoteBody(byte[] payload) {Log.e("fzq", "---------------payloadsize " + payload.length);Bitmap bitmap = BitmapFactory.decodeByteArray(payload, 0,payload.length);iv.setImageBitmap(bitmap);//下列为保存到相册中// 创建Media FileString timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());try {ContentResolver cr = MainActivity.this.getContentResolver();JImageUtils.insertImage(cr, bitmap, "qraved" + timeStamp,"a photo from app", "我是filename没啥用");} catch (Exception e) {e.printStackTrace();}// 对某些不更新相册的应用程序强制刷新Intent intent2 = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);Uri uri = Uri.fromFile(new File("/sdcard/image.jpg"));// 固定写法intent2.setData(uri);MainActivity.this.sendBroadcast(intent2);}private class onclick implements OnClickListener {@Overridepublic void onClick(View v) {selePic();}}private View.OnClickListener mTagWriter = new View.OnClickListener() {@Overridepublic void onClick(View arg0) {// Write to a tag for as long as the dialog is shown.disableNdefExchangeMode();enableTagWriteMode();new AlertDialog.Builder(MainActivity.this).setTitle("Touch tag to write").setOnCancelListener(new DialogInterface.OnCancelListener() {@Overridepublic void onCancel(DialogInterface dialog) {disableTagWriteMode();enableNdefExchangeMode();}}).create().show();}};private Bitmap postBitmap;private Bitmap camorabitmap;private Ndef ndef;NdefMessage[] getNdefMessages(Intent intent) {// Parse the intentNdefMessage[] msgs = null;String action = intent.getAction();if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action)|| NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);if (rawMsgs != null) {msgs = new NdefMessage[rawMsgs.length];for (int i = 0; i < rawMsgs.length; i++) {msgs[i] = (NdefMessage) rawMsgs[i];}} else {// Unknown tag typebyte[] empty = new byte[] {};NdefRecord record = new NdefRecord(NdefRecord.TNF_UNKNOWN,empty, empty, empty);NdefMessage msg = new NdefMessage(new NdefRecord[] { record });msgs = new NdefMessage[] { msg };}} else {Log.d(TAG, "Unknown intent.");finish();}return msgs;}private void enableNdefExchangeMode() {if (mNfcAdapter == null) {mNfcAdapter = NfcAdapter.getDefaultAdapter(this);return;}mNfcAdapter.enableForegroundNdefPush(MainActivity.this, getNoteAsNdef());mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent,mNdefExchangeFilters, null);}private void disableNdefExchangeMode() {mNfcAdapter.disableForegroundNdefPush(this);mNfcAdapter.disableForegroundDispatch(this);}private void enableTagWriteMode() {mWriteMode = true;IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);mWriteTagFilters = new IntentFilter[] { tagDetected };mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent,mWriteTagFilters, null);}private void disableTagWriteMode() {mWriteMode = false;mNfcAdapter.disableForegroundDispatch(this);}boolean writeTag(NdefMessage message, Tag tag) {int size = message.toByteArray().length;try {Ndef ndef = Ndef.get(tag);if (ndef != null) {ndef.connect();if (!ndef.isWritable()) {toast("Tag is read-only.");return false;}if (ndef.getMaxSize() < size) {toast("Tag capacity is " + ndef.getMaxSize()+ " bytes, message is " + size + " bytes.");return false;}ndef.writeNdefMessage(message);toast("Wrote message to pre-formatted tag.");return true;} else {NdefFormatable format = NdefFormatable.get(tag);if (format != null) {try {format.connect();format.format(message);toast("Formatted tag and wrote message");return true;} catch (IOException e) {toast("Failed to format tag.");return false;}} else {toast("Tag doesn't support NDEF.");return false;}}} catch (Exception e) {toast("Failed to write tag");}return false;}private void toast(String text) {Toast.makeText(this, text, Toast.LENGTH_SHORT).show();}@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {switch (requestCode) {case REQUESTCODE_PICK:try {setPicToView(data);} catch (NullPointerException e) {e.printStackTrace();}break;}super.onActivityResult(requestCode, resultCode, data);}private void setPicToView(Intent picdata) {Uri uri = picdata.getData();ContentResolver cr = this.getContentResolver();try {camorabitmap = BitmapFactory.decodeStream(cr.openInputStream(uri));// 显示bitmap的最大效果iv.setImageBitmap(camorabitmap);postBitmap = camorabitmap;getNoteAsNdef();} catch (FileNotFoundException e) {Log.e("Exception", e.getMessage(), e);}}}