FileManager.java

/**
 * Copyright (C) 2015 Fernando Cejas Open Source Project
 * <p/>
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.fernandocejas.android10.sample.data.cache;

import android.content.Context;
import android.content.SharedPreferences;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

/**
 * Helper class to do operations on regular files/directories.
 */
public class FileManager {

	public FileManager() {
	}

	/**
	 * Writes a file to Disk.
	 * This is an I/O operation and this method executes in the main thread, so it is recommended to
	 * perform this operation using another thread.
	 *
	 * @param file The file to write to Disk.
	 */
	public void writeToFile(File file, String fileContent) {
		if (!file.exists()) {
			try {
				FileWriter writer = new FileWriter(file);
				writer.write(fileContent);
				writer.close();
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			} finally {

			}
		}
	}

	/**
	 * Reads a content from a file.
	 * This is an I/O operation and this method executes in the main thread, so it is recommended to
	 * perform the operation using another thread.
	 *
	 * @param file The file to read from.
	 * @return A string with the content of the file.
	 */
	public String readFileContent(File file) {
		StringBuilder fileContentBuilder = new StringBuilder();
		if (file.exists()) {
			String stringLine;
			try {
				FileReader fileReader = new FileReader(file);
				BufferedReader bufferedReader = new BufferedReader(fileReader);
				while ((stringLine = bufferedReader.readLine()) != null) {
					fileContentBuilder.append(stringLine + "\n");
				}
				bufferedReader.close();
				fileReader.close();
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

		return fileContentBuilder.toString();
	}

	/**
	 * Returns a boolean indicating whether this file can be found on the underlying file system.
	 *
	 * @param file The file to check existence.
	 * @return true if this file exists, false otherwise.
	 */
	public boolean exists(File file) {
		return file.exists();
	}

	/**
	 * Warning: Deletes the content of a directory.
	 * This is an I/O operation and this method executes in the main thread, so it is recommended to
	 * perform the operation using another thread.
	 *
	 * @param directory The directory which its content will be deleted.
	 */
	public void clearDirectory(File directory) {
		if (directory.exists()) {
			for (File file : directory.listFiles()) {
				file.delete();
			}
		}
	}

	/**
	 * Write a value to a user preferences file.
	 *
	 * @param context {@link android.content.Context} to retrieve android user preferences.
	 * @param preferenceFileName A file name reprensenting where data will be written to.
	 * @param key A string for the key that will be used to retrieve the value in the future.
	 * @param value A long representing the value to be inserted.
	 */
	public void writeToPreferences(Context context, String preferenceFileName, String key,
	                               long value) {

		SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceFileName,
				Context.MODE_PRIVATE);
		SharedPreferences.Editor editor = sharedPreferences.edit();
		editor.putLong(key, value);
		editor.apply();
	}

	/**
	 * Get a value from a user preferences file.
	 *
	 * @param context {@link android.content.Context} to retrieve android user preferences.
	 * @param preferenceFileName A file name representing where data will be get from.
	 * @param key A key that will be used to retrieve the value from the preference file.
	 * @return A long representing the value retrieved from the preferences file.
	 */
	public long getFromPreferences(Context context, String preferenceFileName, String key) {
		SharedPreferences sharedPreferences = context.getSharedPreferences(preferenceFileName,
				Context.MODE_PRIVATE);
		return sharedPreferences.getLong(key, 0);
	}
}