FileSystem.java

package com.tns;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URI;
import java.net.URISyntaxException;

import org.json.JSONException;
import org.json.JSONObject;

public class FileSystem {
    private static final String appRootPrefix = "~/";

    public static String readAll(InputStream inputStream) throws IOException {
        StringBuilder text;
        BufferedReader buffReader = null;

        try {
            buffReader = new BufferedReader(new InputStreamReader(inputStream));
            String line;
            text = new StringBuilder();

            while ((line = buffReader.readLine()) != null) {
                text.append(line);
                text.append('\n');
            }
        } catch (IOException e) {
            return "";
        } finally {
            if (buffReader != null) {
                buffReader.close();
            }
        }

        return text.toString();
    }

    private final static byte[] buff = new byte[65536];

    public static String readText(File file) throws FileNotFoundException, IOException {
        int fileLength = (int) file.length();
        if (fileLength < buff.length) {
            FileInputStream fis = null;
            try {
                fis = new FileInputStream(file);
                int length = fis.read(buff, 0, fileLength);
                return new String(buff, 0, length);
            } finally {
                if (fis != null) {
                    fis.close();
                }
            }
        } else {
            BufferedInputStream inputStream = null;
            try {
                inputStream = new BufferedInputStream(new FileInputStream(file));
                return readAll(inputStream);
            } catch (FileNotFoundException e) {
                return "";
            } finally {
                if (inputStream != null) {
                    inputStream.close();
                }
            }
        }
    }

    public static JSONObject readJSONFile(File file) throws IOException, JSONException {
        String content = readText(file);
        return new JSONObject(content);
    }

    public static String resolveRelativePath(String applicationFilesDir, String path, String currentDirectory) {
        String baseDir;
        if (path.startsWith(appRootPrefix)) {
            baseDir = new File(applicationFilesDir, "app").getAbsolutePath();
            path = path.substring(appRootPrefix.length());
        } else {
            baseDir = currentDirectory;
        }
        File temp = new File(baseDir, path);
        try {
            return temp.getCanonicalPath();
        } catch (IOException e) {
            try {
                URI uri = new URI(baseDir);
                return uri.resolve(path).getPath();
            } catch (URISyntaxException e1) {
                return null;
            }
        }
    }
}