CacheClient.java

package com.rogoapp;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;

import android.content.Context;
import android.util.Log;

// how to write to files:
// http://developer.android.com/guide/topics/data/data-storage.html#filesInternal

// a detailed case here:
// http://web.archive.org/web/20110803104357/http://www.flexjockey.com/2011/03/create-a-pretty-simple-cache-for-android/

public class CacheClient {

	final Context context;
	
	//Error messages
	public static final String ERROR_1 = "ERROR_1: File not found";
	public static final String ERROR_2 = "ERROR_2: File cannot be written to.";
	public static final String ERROR_3 = "ERROR_3: File data cannot be accessed.";
	
    public final static String SESSION_CACHE = "adfad234_343-45dsffsdg83-dafptjv";

	
	public CacheClient(Context context) { // from an Activity, pass "this"
		this.context = context;
	}
	
	public void saveFile(String filename, String content) {
		File cacheDir = context.getCacheDir();
		File file = new File(cacheDir, filename);

		FileOutputStream fos;
		try {
			fos = new FileOutputStream(file);
			fos.write(content.getBytes());
			fos.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			Log.d(ERROR_1, "Searching for " + filename);
		} catch (IOException e) {
			e.printStackTrace();
			Log.d(ERROR_2, "Writing to " + filename);
		}
	}
	
	public void addToFile(String filename, String content){
		File cacheDir = context.getCacheDir();
		File file = new File(cacheDir, filename);

		FileOutputStream fos;
		try {
			fos = new FileOutputStream(file, true); // true means go to end of file
			fos.write(content.getBytes());
			fos.close();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			Log.d(ERROR_1, "Searching for " + filename);
		} catch (IOException e) {
			e.printStackTrace();
			Log.d(ERROR_2, "Writing to " + filename);
		}
	}
	
	public boolean deleteLineFromFile(String filename, String lineToDelete){
		File cacheDir = context.getCacheDir();
		File file = new File(cacheDir, filename);

		StringBuilder contentString = new StringBuilder();

		FileInputStream fis;
		try {
			fis = new FileInputStream(file);
			int content1;
			while((content1 = fis.read()) != -1){
				contentString.append((char)content1);
			}
			fis.close();

		} catch (FileNotFoundException e) {
			e.printStackTrace();
			Log.d(ERROR_1, "Searching for " + filename);
			return false;
		} catch (IOException e) {
			e.printStackTrace();
			Log.d(ERROR_3, "Reading from " + filename);
			return false;
		}
		
		String[] contentLines = contentString.toString().split("\n");
		int lineNumberToDelete = -1;
		for (int i=0; i<contentLines.length; i++) {
			if (contentLines[i].equals(lineToDelete)) {
				lineNumberToDelete = i;
				break;
			}
		}
		
		if (lineNumberToDelete == -1) return false; // wasn't in there
		
		FileOutputStream fos;
		try {
			fos = new FileOutputStream(file, true);
			for (int i = 0; i < contentLines.length; i++) if (i != lineNumberToDelete) {
				fos.write(contentLines[i].getBytes());
				fos.write("\n".getBytes());
			}
			fos.close();
			return true;
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			Log.d(ERROR_1, "Searching for " + filename);
		} catch (IOException e) {
			e.printStackTrace();
			Log.d(ERROR_2, "Writing to " + filename);
		}
		
		return false;
	}
	
	public String loadFile(String filename){
		File cacheDir = context.getCacheDir();
		File file = new File(cacheDir, filename);
		
		StringBuilder contentString = new StringBuilder();

		FileInputStream fis;
		try {
			fis = new FileInputStream(file);
			int content;
			while((content = fis.read()) != -1){
				contentString.append((char)content);
			}
			fis.close();

			return contentString.toString();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			Log.d(ERROR_1, "Searching for " + filename);
			return ERROR_1 + " " + filename;
		} catch (IOException e) {
			e.printStackTrace();
			Log.d(ERROR_3, "Reading from " + filename);
			return ERROR_3+"File: " + filename;
		}

	}
	
	public boolean isEmpty(String filename){
		File cacheDir = context.getCacheDir();
		File file = new File(cacheDir, filename);
		return !((int) file.length() > 0);
	}
	
	
	
	public int lines(String filename){
		
		try{
			
			File cacheDir = context.getCacheDir();
			File file = new File(cacheDir,filename); 

			if(file.exists()){

				FileReader fr = new FileReader(file);
				LineNumberReader lnr = new LineNumberReader(fr);

				int linenumber = 0;

				while (lnr.readLine() != null){
					linenumber++;
				}

				lnr.close();
				return linenumber;

			}else{
				System.out.println("File does not exists!");
				return 0;
			}

		}catch(IOException e){
			e.printStackTrace();
			return -1;
		}
	}

}