Android db file copy backup 資料庫 檔案 複製 備份

備份資料庫或檔案到其他位置，加入下列程式碼

try {
         File sd = Environment.getExternalStorageDirectory(); //複製到哪裡
         File data = Environment.getDataDirectory(); //原始位置

         if (sd.canWrite()) {
             String currentDBPath = "//data//com.httc.pipeline//xxx.db"; //原始位置檔名
             String backupDBPath = "xxx.db"; //複製位置檔名
             File currentDB = new File(data, currentDBPath);
             File backupDB = new File(sd, backupDBPath);
             Log.i("currentDB", currentDB+"");
             Log.i("backupDB", backupDB+"");
             if (currentDB.exists()) { //原始檔案存在
                 FileChannel src = new FileInputStream(currentDB).getChannel();
                 FileChannel dst = new FileOutputStream(backupDB).getChannel();
                 dst.transferFrom(src, 0, src.size()); //開始複製
                 Log.i("dst", dst+"");
                 src.close();
                 dst.close();
             }
         }
     } catch (Exception e) {
       Log.i("eDB", e+"");
     }

參考來源: http://stackoverflow.com/questions/1995320/how-to-backup-database-file-to-sdcard-on-android

Android TableLayout Center 置中

TableLayout排版文字置中問題
方法1:
TableLayout加入
android:shrinkColumns="*"
android:stretchColumns="*"

方法二:text使用比重

參考來源: http://mrbool.com/how-to-deal-with-table-layout-in-android/28008

Android NFC Activity disable 關閉 近距離無線通訊

前篇有用到NFC使用方法，在可以使用NFC APP上，我們可能想要在一個頁面(Activity1)可以使用NFC，在下一個頁面(Activity2)不需要用到NFC，但是若沒有設定，仍會感應到tag資料，

所以需加上下列程式碼

/*此頁面關閉NFC感應*/
 @Override
 protected void onResume() {
  super.onResume();
  // creating pending intent:
  PendingIntent pendingIntent = PendingIntent.getActivity(this, 0,
    new Intent(this, getClass())
      .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
  // enabling foreground dispatch for getting intent from NFC event:
  NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);
  try {
//   nfcAdapter.enableForegroundDispatch(this, pendingIntent,
//     new IntentFilter[] { filter }, this.techList);  開啟nfc
   nfcAdapter.enableForegroundDispatch(this, pendingIntent,
     new IntentFilter[] {}, null); // 關閉nfc IntentFilter[] {}內設為空值， techList改為null空值
  } catch (NullPointerException e) {
  }
 }

參考資料: http://stackoverflow.com/questions/9748513/reading-nfc-tags-only-from-a-particuar-activity

Android camera flashlight 相機閃光燈

簡易手電筒app，開啟相機的閃光燈
1.AndroidManifest.xml 加入
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />

2.main.xml

2.MainActivity.java

package com.prgguru.com;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {
 private boolean isFlashOn = false; //預設開關-關閉
 private Camera camera;
 private Button button;

 @Override
 protected void onStop() {
  super.onStop();

  if (camera != null) {
   camera.release();
  }
 }

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  button = (Button) findViewById(R.id.buttonFlashlight);
  Context context = this;
  PackageManager pm = context.getPackageManager();

  
  if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) { //判斷有無相機
   Toast.makeText(getApplicationContext(),
     "抱歉，您的手機無相機功能",
     Toast.LENGTH_SHORT).show();

   return;
  }

  camera = Camera.open();
  final Parameters p = camera.getParameters();

  button.setOnClickListener(new OnClickListener() {
   public void onClick(View arg0) {
    if (isFlashOn) { //false 關閉
     p.setFlashMode(Parameters.FLASH_MODE_OFF); //相機閃光燈模式
     camera.setParameters(p);     
     isFlashOn = false;
     button.setText("打開");
    } else { // true 開啟
     Log.i("info", "torch is turned on!");
     p.setFlashMode(Parameters.FLASH_MODE_TORCH); //相機閃光燈模式
     camera.setParameters(p);     
     isFlashOn = true;
     button.setText("關閉");
    }
   }
  });

 }
}

參考來源: http://programmerguru.com/android-tutorial/android-flashlight-example/