org.indigo.cdmi.backend.radosgw.JsonUtils.java Source code

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Here is the source code for org.indigo.cdmi.backend.radosgw.JsonUtils.java

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/*
 * Copyright 2016 Poznan Supercomputing and Networking Center (PSNC)
 * 
 * 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
 */

package org.indigo.cdmi.backend.radosgw;

import org.json.JSONArray;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

/**
 * Provides auxiliary methods to operate on JSON objects and Strings representing JSON objects.
 * 
 * @author @author Gracjan Jankowski (gracjan@man.poznan.pl)
 */
public class JsonUtils {

    /**
     * Reads file pointed by path and returns the content of the file in String format.
     * (The assumption is that the file contains UTF-8 encoded JSON object.)
     * 
     * @param path Path to file with UTF-8 encoded JSON object.
     * 
     * @return String with value representing content of file pointed by path.
     */
    private static String fileToString(String path) {

        InputStream inputStream = null;
        try {
            inputStream = new FileInputStream(path);
        } catch (FileNotFoundException ex) {
            throw new RuntimeException(String.format("Failed to open %s file.", path), ex);
        }

        BufferedReader bufferedReader = null;
        try {
            bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
        } catch (UnsupportedEncodingException ex1) {
            try {
                inputStream.close();
            } catch (IOException ex2) {
                // empty, on purpose
            }
            throw new RuntimeException(String.format(
                    "File with definition of all available profiles %s is encoded in unsupported format",
                    inputStream), ex1);
        }

        /*
         * each line read will be added to that buffer
         */
        StringBuffer stringBuilder = new StringBuffer();

        /*
         * iterate through all available lines
         */
        try {

            String line = bufferedReader.readLine();

            while (line != null) {
                stringBuilder.append(line);
                line = bufferedReader.readLine();
            }

        } catch (IOException ex) {

            throw new RuntimeException(
                    String.format("Failed to read definition of all available profiles from %s", path), ex);

        } finally {

            try {
                inputStream.close();
            } catch (IOException ex1) {
                // empty, on purpose
            }

        }

        return stringBuilder.toString();

    } // fileToString

    /**
     * Converts JSON object, from the file pointed by path parameter, to JSONObject.
     * 
     * @param path Path to UTF-8 encoded file with JSON.
     * 
     * @return JSONObject created from file pointed by path parameter.
     */
    public static JSONObject createJsonObjectFromFile(String path) {

        String jsonObjectAsString = fileToString(path);

        JSONObject rv = new JSONObject(jsonObjectAsString);

        return rv;

    } // createJsonObjectFromFile

    /**
     * Converts JSON object, from the file pointed by path parameter, to JSONArrsy. 
     * 
     * @param path Path to UTF-8 encoded file with JSON (exactly, with JSON array).
     * 
     * @return JSONArray created from file pointed by path parameter.
     */
    public static JSONArray createJsonArrayFromFile(String path) {

        String jsonArrayAsString = fileToString(path);

        JSONArray rv = new JSONArray(jsonArrayAsString);

        return rv;

    } // createJsonArrayFromFile()

} // end of JsonUtils class