edu.uniandes.ecos.codeaholics.config.GeneralUtil.java Source code

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Here is the source code for edu.uniandes.ecos.codeaholics.config.GeneralUtil.java

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/** Copyright or License
 *
 */

package edu.uniandes.ecos.codeaholics.config;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.HashMap;
import java.util.UUID;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

import spark.ModelAndView;
import spark.ResponseTransformer;
import spark.template.freemarker.FreeMarkerEngine;
import spark.Request;

/**
 * Created by davidMtz on 27/6/16.
 */
public final class GeneralUtil {

    // Atributos
    private final static Logger log = LogManager.getLogger(GeneralUtil.class);

    // Metodos
    /***
     * Convierte un arreglo de bytes a String usando valores hexadecimales
     * 
     * @param digest arreglo de bytes a convertir
     * @return String creado a partir de digest
     */
    private static String toHexadecimal(byte[] pDigest) {

        String hash = "";
        for (byte aux : pDigest) {
            int b = aux & 0xff;
            if (Integer.toHexString(b).length() == 1)
                hash += "0";
            hash += Integer.toHexString(b);
        }
        return hash;
    }

    /***
     * Encripta una cadena mediante algoritmo de resumen de mensaje.
     * 
     * @param pPwd texto a encriptar
     * @return mensaje encriptado
     */
    public static String[] getHash(String pPwd, String pSalt) {

        if (pSalt.equals("")) {
            pSalt = getSalt();
        }
        String saltedPwd = pSalt + pPwd;
        String[] result = new String[2];
        result[0] = pSalt;
        byte[] digest = null;
        byte[] buffer = saltedPwd.getBytes();
        try {
            MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
            messageDigest.reset();
            messageDigest.update(buffer);
            digest = messageDigest.digest();
        } catch (NoSuchAlgorithmException ex) {
            log.error("Error creating hash");
        }
        result[1] = toHexadecimal(digest);
        return result;
    }

    /***
     * Genera el salt para poder encriptar.
     * 
     * @return salt de encriptacion
     */
    private static String getSalt() {

        String salt = String.valueOf(UUID.randomUUID());
        return salt;
    }

    /**
     * @param object
     * @return
     */
    public static String toJson(Object pObject) {

        return new Gson().toJson(pObject);
    }

    /**
     * @return
     */
    public static ResponseTransformer json() {

        return GeneralUtil::toJson;
    }

    /**
     * @param templatePath
     * @param model
     * @return
     */
    public static String render(String pTemplatePath, HashMap<String, Object> pModel) {

        return new FreeMarkerEngine().render(new ModelAndView(pModel, pTemplatePath));
    }

    /**
     * @return
     */
    public static String randomPassword() {
        String result = null;
        String string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
        SecureRandom rnd = new SecureRandom();
        int length = 10;

        StringBuilder sb = new StringBuilder(length);
        for (int i = 0; i < length; i++)
            sb.append(string.charAt(rnd.nextInt(string.length())));
        result = sb.toString();

        return result;
    }

    /**
     * @param pRequest
     * @param pKey
     * @return
     */
    public static String extractFromBody(Request pRequest, String pKey) {

        JsonParser parser = new JsonParser();
        JsonObject json = parser.parse(pRequest.body()).getAsJsonObject();
        String value = "";
        if (json.getAsJsonObject().has(pKey)) {
            value = json.getAsJsonObject().get(pKey).getAsString();
            log.info("Found key with value: " + value);
        }
        return value;

    }

    public static String executeCommand(String command) {

        //credit: http://www.mkyong.com/java/how-to-execute-shell-command-from-java/
        StringBuffer output = new StringBuffer();

        Process p;
        try {
            p = Runtime.getRuntime().exec(command);
            p.waitFor();
            BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));

            String line = "";
            while ((line = reader.readLine()) != null) {
                output.append(line + "\n");
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return output.toString();

    }

}