GoogleMaps API multiple markers

I have a database with some records that among other details they also declare a local (Greek) street addresses. The requirement is to retrieve all these records from the database and display them with markers on a Google Map. Before everything, if you want to get an idea on how the API works see the following links:

GoogleMaps API – Getting started
GoogleMaps API – Simple markers

The flow for my task has as follows:

– Connect to database
– Retrieve all the locations from DB
– Convert Greek characters to Latin for avoiding issues with the Web Service request [ code on code.loon.gr ]
– Use GoogleMaps API to retrieve GPS coordinates based on the given location
– Parse JSON response
– Use JavaScript to add the markers layers

Full code on GitHub.

 

Java HTTP library

Being in need to issue POST requests from within a Java application, and wanting re-usable code, I created a very simple Java library for issuing POST and GET requests to a remote server.

POST source codeGET source code

Usage (POST example):

POST post = new POST();
post.postRequest("http://www.myservice.com/service", "param1=foo&param2=bar", "Mozilla/5.0");

In other words, the arguments are:

post.postRequest(SERVER_URL, PARAMETERS, AGENT);

The output can be manipulated as desired, depending on what you response you except you should use a corresponding element/object.

Java libary in Android project

If you have developed your Java library that you would like to use within your Android project, or you want to use an existing Java library, make sure that the library itself is compiled with Java 1.6 rather than 1.7. Have been always forgetting that and have wondering for a couple of days why am I getting “NoClassDefFoundError” error.

Assigning HTML “rel” attribute to all page images

Very briefly, in a CakePHP app, I want to apply the lightbox script on all the images that link from a thumbnail to a larger image. If there are more than two, I want them to appear as a lightbox group. I don’t want the user to mess with TinyMCE and HTML, therefore I automatically apply the rel attributed for every single image in a page that is a hyperlink. The following PHP bit is added in app/Plugin/Nodes/View/Nodes/view.ctp. With some small changes it can be used for any PHP compatible web site.

$body = $this->Nodes->body();
if (strpos($body, "img")) {
   $pattern ="/<a(.*?)href=('|\")(.*?).(jpeg|jpg|png)('|\")(.*?)>/i";
   $newLink = '<a$1href=$2$3.$4$5 rel="lightbox[group]".$6>';
   echo preg_replace($pattern, $newLink, $body);
} else {
   echo $body;
}

Java encrypt class

A simple implementation of an encryption class to be used in Java applications for either encrypting strings and calculating files’ fingerprint.

import java.io.FileInputStream;
import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Encrypt {

   private FileInputStream fis;

   public Encrypt() { }

   public String encryptString(String input, String salt, String algorithm) {
      String output = null;
      String fullInput = null;

      if (!salt.equals(null)) {
         fullInput = salt + input;
      } else {
         fullInput = input;
      }

      try {
         MessageDigest digest = MessageDigest.getInstance(algorithm);
         digest.update(fullInput.getBytes(), 0, fullInput.length());
         output = new BigInteger(1, digest.digest()).toString(16);
      } catch (NoSuchAlgorithmException ex) {
         ex.printStackTrace();
      }
      return output;
   }

   // Based on: http://www.mkyong.com/java/how-to-generate-a-file-checksum-value-in-java/
   public String calculateFingerprint(String fileName, String algorithm) {
      StringBuffer sb = new StringBuffer();
      try {
         MessageDigest md = MessageDigest.getInstance(algorithm);
         fis = new FileInputStream(fileName);
         byte[] dataBytes = new byte[1024];
         int nread = 0;
         while ((nread = fis.read(dataBytes)) != -1) { md.update(dataBytes, 0, nread); }
         byte[] mdbytes = md.digest();
         for (int i = 0; i < mdbytes.length; i++) {
            sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
         }
      } catch (Exception ex) {
         ex.printStackTrace();
      }
      return sb.toString();
   }
}

Link to GiHub repository. The class is intended to be used as a library within Java applications.

Example for encrypting a string:

Encrypt en = new Encrypt();
String encryptedString = en.encryptString(textField.getText().toString(), \
"salt goes here if you want", "md5")));

Example for calculating the fingerprint of a file:

Encrypt en = new Encrypt();
String fingerPrint = en.calculateFingerprint("/path/to/file", sha1);

Android SQLite Adapter class

Working with an SQLite database on Android can require some times more effort than what you should really give. For instance, if you ship a pre-configured and populated database with an application, you would need first to copy over the database to the specific database directory and then open it for reading and/or writing data to it. The SQLiteOpenHelper class provides a few methods that make life a bit easier but it does not provide a copy method for handling this issue. In addition to this, a check method would be required before copying the database and so on. Following on this, I implemented a SQLite adapter class to cover my needs as bellow:

– Copy database to the correct directory.
– Open and close the database.
– Execute raw SQL query.
– Execute SQL query for string, int, long, double.
– Drop table.
– Return count of a table.
– Download a db copy from Internet and replace local one.

Source code at GitHub.