Android Output Write File 輸出 寫入 文件

有時候字串太長，LogCat不好顯示，輸出文件是個好方法。
1.AndroidManifest.xml加入權限

2./res/layout/activity_main.xml

3.Write.java

package tw.android;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import android.content.Context;
import android.os.Environment;
import android.util.Log;
import android.widget.Toast;

public class Write {
 private static Context context;

 public Write(Context context) {
  this.context = context;
 }
 
 public static void WriteFileExample(String message) {
  FileOutputStream fop = null;
  File file;
  String content = message;

  try {
   File sdcard = Environment.getExternalStorageDirectory();
   file = new File(sdcard, context.getResources().getString(R.string.app_name)+"Log.txt"); //輸出檔案位置
   Log.i("Write File:", file + "");
   fop = new FileOutputStream(file);
   
   if (!file.exists()) { // 如果檔案不存在，建立檔案
    file.createNewFile();
   }

   byte[] contentInBytes = content.getBytes();// 取的字串內容bytes

   fop.write(contentInBytes); //輸出
   fop.flush();
   fop.close();

   Toast.makeText(context, "輸出完成", Toast.LENGTH_LONG).show();
   
  } catch (IOException e) {
   Log.i("Write E:", e + "");
   e.printStackTrace();
  } finally {
   try {
    if (fop != null) {
     fop.close();
    }
   } catch (IOException e) {
    Log.i("Write IOException", e + "");
    e.printStackTrace();
   }
  }
 }
}

4.MainActivity.java

package tw.android;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity {
 private EditText etWrite;
 private Button btWrite;
 private Write write = new Write(MainActivity.this);

 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  etWrite = (EditText) findViewById(R.id.etWrite);
  btWrite = (Button) findViewById(R.id.btWrite);

  btWrite.setOnClickListener(new Button.OnClickListener() {
   public void onClick(View v) {

    write.WriteFileExample(etWrite.getText().toString()); // 寫入輸入文字
   }
  });

 }
}

檔案下載:
https://github.com/terryyamg/WriteFileTest
參考連結:
http://www.mkyong.com/java/how-to-write-to-file-in-java-fileoutputstream-example/

Android NFC tag writer 寫入 訊息

NFC感應TAG，將訊息寫入TAG中
1.AndroidManifest.xml
加入權限
與最低版本
android:minsdkversion="17" android:targetsdkversion="17"
2.activity_main.xml

3.MainActivity.java

import java.io.IOException;
import nl.paulus.nfctagwriter.R;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.PendingIntent;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
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.Parcelable;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

/**
 * Activity to write NFC tags with own mimetype and ID Based on the excellent
 * tutorial by Jesse Chen
 * http://www.jessechen.net/blog/how-to-nfc-on-the-android-platform/
 */
public class MainActivity extends Activity {

 boolean mWriteMode = false;
 private NfcAdapter mNfcAdapter;
 private PendingIntent mNfcPendingIntent;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  ((Button) findViewById(R.id.button))
    .setOnClickListener(new OnClickListener() {

     @Override
     public void onClick(View v) {
      mNfcAdapter = NfcAdapter
        .getDefaultAdapter(MainActivity.this);
      mNfcPendingIntent = PendingIntent.getActivity(
        MainActivity.this,
        0,
        new Intent(MainActivity.this,
          MainActivity.class)
          .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP),
        0);
      //開啟寫入
      enableTagWriteMode();

      new AlertDialog.Builder(MainActivity.this)
        .setTitle("感應tag寫入")
        .setOnCancelListener(
          new DialogInterface.OnCancelListener() {
           @Override
           public void onCancel(
             DialogInterface dialog) {
            //關閉寫入
            disableTagWriteMode();
           }

          }).create().show();
     }
    });
 }

 private void enableTagWriteMode() {
  mWriteMode = true;
  IntentFilter tagDetected = new IntentFilter(
    NfcAdapter.ACTION_TAG_DISCOVERED);
  IntentFilter[] mWriteTagFilters = new IntentFilter[] { tagDetected };
  mNfcAdapter.enableForegroundDispatch(this, mNfcPendingIntent,
    mWriteTagFilters, null);
 }

 private void disableTagWriteMode() {
  mWriteMode = false;
  mNfcAdapter.disableForegroundDispatch(this);
 }

 @SuppressLint("NewApi")
 @Override
 protected void onNewIntent(Intent intent) {
  // Tag writing mode
  if (mWriteMode
    && NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())) {
   Tag detectedTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
   NdefRecord record = NdefRecord.createMime( //需要Android 4.1(API Level 16)
     ((TextView) findViewById(R.id.mime)).getText().toString(),
     ((TextView) findViewById(R.id.value)).getText().toString()
       .getBytes());
   NdefMessage message = new NdefMessage(new NdefRecord[] { record });
   if (writeTag(message, detectedTag)) {
    Toast.makeText(this, "成功寫入!",
      Toast.LENGTH_LONG).show();
   }
  }
  
  //讀取寫入訊息 看是否有寫入
  
        try {
         Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
      NdefMessage[] msgs = new NdefMessage[rawMsgs.length];
      for (int i = 0; i < rawMsgs.length; i++) {
                msgs[i] = (NdefMessage) rawMsgs[i];
            }

            NdefMessage msg = msgs[0];
         String msgstring = new String(msg.getRecords()[0].getPayload(), "UTF-8");
         Toast.makeText(getApplicationContext(), msgstring, Toast.LENGTH_LONG).show();
   
        } catch (Exception e) {
            e.printStackTrace();
        }
 }

 /* 檢查訊息 */
 public 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.makeText(getApplicationContext(),
       "Error: tag not writable", Toast.LENGTH_SHORT)
       .show();
     return false;
    }
    if (ndef.getMaxSize() < size) {
     Toast.makeText(getApplicationContext(),
       "Error: tag too small", Toast.LENGTH_SHORT).show();
     return false;
    }
    ndef.writeNdefMessage(message);
    return true;
   } else {
    NdefFormatable format = NdefFormatable.get(tag);
    if (format != null) {
     try {
      format.connect();
      format.format(message);
      return true;
     } catch (IOException e) {
      return false;
     }
    } else {
     return false;
    }
   }
  } catch (Exception e) {
   return false;
  }
 }
} 

參考來源:
https://github.com/balloob/Android-NFC-Tag-Writer 
http://stackoverflow.com/questions/7917567/strange-character-on-android-ndef-record-payload