DataStorage.java

/*
 * Copyright (C) 2011 asksven
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.asksven.android.common.utils;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.util.Log;

/**
 * @author sven
 *
 */
public class DataStorage
{
	/**
	 * 
	 * The logging TAG
	 */
	private static final String TAG = "DataStorage";
	
	public static boolean isExternalStorageWritable()
	{
		boolean mExternalStorageAvailable = false;
		boolean mExternalStorageWriteable = false;
		String state = Environment.getExternalStorageState();

		if (Environment.MEDIA_MOUNTED.equals(state)) {
		    // We can read and write the media
		    mExternalStorageAvailable = mExternalStorageWriteable = true;
		} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
		    // We can only read the media
		    mExternalStorageAvailable = true;
		    mExternalStorageWriteable = false;
		} else {
		    // Something else is wrong. It may be one of many other states, but all we need
		    //  to know is we can neither read nor write
		    mExternalStorageAvailable = mExternalStorageWriteable = false;
		}
		
		return ( mExternalStorageAvailable && mExternalStorageWriteable );
	}
	
	public static void LogToFile(String fileName, StackTraceElement[] stack)
	{
		LogToFile(fileName, "---- Begin Callstack ----");
		for (int i = 0; i < stack.length; i++)
		{
			LogToFile(fileName, stack[i].toString());
		}
		LogToFile(fileName, "---- End Callstack ----");
	}
	
	public static void LogToFile(String fileName, String strText)
	{
		
		try
    	{		
			// open file for writing
			File root = Environment.getExternalStorageDirectory();
		    if (root.canWrite())
		    {
		    	File dumpFile = new File(root, fileName);
		    	// append
		        FileWriter fw = new FileWriter(dumpFile, true);
		        BufferedWriter out = new BufferedWriter(fw);
			  
				// write header
		        out.write(DateUtils.now() + " " + strText + "\n");
						
				// close file
				out.close();
		    }
    	}
    	catch (Exception e)
    	{
    		Log.e(TAG, "Exception: " + e.getMessage());
    	}		
	}
	
	public static synchronized boolean objectToFile(Context context, String fileName, Object serializableObject)
	{
		boolean bRet = true;
		
		 if (!(serializableObject instanceof java.io.Serializable))
		 {
			 Log.e(TAG, "The object is not serializable: " + fileName);
		     return false;
		 }
		try
		{
			FileOutputStream fos = context.openFileOutput(fileName, Context.MODE_PRIVATE);
			ObjectOutputStream os = new ObjectOutputStream(fos);
			os.writeObject(serializableObject);
			os.close();
		}
		catch (Exception e)
		{
			 Log.e(TAG, "An error occured while writing " + fileName + " " + e.getMessage());

			bRet = false;
		}

		return bRet;
	}
	
	public static synchronized Object fileToObject(Context context, String fileName)
	{
		FileInputStream fis;
		Object myRet = null;
		try
		{
			fis = context.openFileInput(fileName);
			ObjectInputStream is = new ObjectInputStream(fis);
			myRet = is.readObject();
			is.close();

		}
		catch (FileNotFoundException e)
		{
			myRet = null;
		}
		catch (IOException e)
		{
			myRet = null;
		}
		catch (ClassNotFoundException e)
		{
			myRet = null;
		}

		return myRet;
	}
	
	/** forces the mediascanner to "see" a file that was just created
	 * This is a workaround (see http://stackoverflow.com/questions/3300137/how-can-i-refresh-mediastore-on-android/14849652#14849652)
	 * 
	 * @param file the Uri of the newly created file
	 */
	public static void forceMediaScanner(Context context, Uri fileUri)
	{
		context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, fileUri));
	}
}