Sunday, January 27, 2013

Java and Lombok

If you are an Indonesian, it's pretty easy to make a connection between Java and Lombok. However, this post is not about that Java and Lombok, but rather for the Java programming language and Project Lombok.

One of the drawback of Java language is its verbosity. One very easy example can be found in any typical Java POJO.

public class Order{

  private long id;
  private String name;
  private int size;

  public Order(){
  }

  public Order(long id){
    this.id = id;
  }

  public long getId(){
    return id;
  }

  public void setId(long id){
    this.id = id;
  }

  public String getName(){
    return name;
  }

  public void setName(String name){
    this.name = name;
  }

  public int getSize(){
    return size();
  }

  public void setSize(int size){
    this.size = size;
  }

  @Override
  public String toString(){
    return String.format("%s %d %d", id, name, size);
  }
}


Already that much code just for a very simple structure with constructors, getters, setters, and toString method. This is where Lombok comes to save the day! Instead of writing that much code, you can have something like this:

@Data
public class Order{

  private long id;
  private String name;
  private int size;
}

...and that's it! A clean, nice code that is easy to maintain. The @Data annotation will tell Lombok to generate the constructor, getters and setters, toString method (and even equals and hashCode method!) all during compilation time! (instead of hiding the code in other file ala AspectJ). Since Lombok can be integrated with your IDE, you will not lose the nice content assist or any other feature that you currently enjoying.

There are several other features provided by Lombok (see: Lombok features), although personally for me, this one is going to be the one I use the most. I am not too scared of introducing Lombok dependency to my project since Lombok itself presented a nice way to stop using Lombok dependency with a tool called "delombok". By using delombok, all magically generated code will be written to the source code and the dependency to Lombok library will be removed.

The only drawback I can think of is whenever I rename one of the field name and the rest of code which refer to the getter/setter will also need to be updated manually (instead of having them automatically updated using a refactor tool in your IDE), but it is a very small price to pay (I guess).

Saturday, January 07, 2012

Software of the day: Fence


Fence is a software created by Stardock that helps organize icons/files in your Windows's desktop. Basically what a user can do is to create a "fence" (kind of group) and associate icons of your choice into it. The fences are blocks that does not enlarge/shrink according to the number of icons/files you put there, but instead the size are determined by the user themselves. Thus, no matter how many icons/files you have, it will still look like it's very well organized ;)

For someone like me who loves to put everything in desktop (who doesn't?), Fence is a must-have-tool. Quite often I put something that I would need immediately, but most probably wouldn't be for long in the desktop. Fence help he organize it so that in the future it is very easy to find find and remove them. Another nice thing that I like: Fence does not separate the icons in different fences to actual different directories, so it does not mess up the files location.

Fence is free, and if you want more features, they have a paid version for it as well.

screen shot was taken from Fence website

Monday, May 02, 2011

Using ClientLogin to do Authentication for App Engine Application

General information about ClientLogin: http://code.google.com/apis/accounts/docs/AuthForInstalledApps.html

Discussion on Google Groups (including the original solution posted by geoffd123):
http://groups.google.com/group/google-appengine-java/browse_thread/thread/c96d4fff73117e1d

My solution uses Apache Http library instead of HttpUnit.
public static String loginToGoogle(String userid, String password,
   String appUrl) throws Exception {
  HttpClient client = new DefaultHttpClient();
  HttpPost post = new HttpPost(
    "https://www.google.com/accounts/ClientLogin");
  
  MultipartEntity reqEntity = new MultipartEntity();
  reqEntity.addPart("accountType", new StringBody("HOSTED_OR_GOOGLE",
    "text/plain", Charset.forName("UTF-8")));
  reqEntity.addPart("Email", new StringBody(userid));
  reqEntity.addPart("Passwd", new StringBody(password));
  reqEntity.addPart("service", new StringBody("ah"));
  reqEntity.addPart("source", new StringBody(
    "YourCompany-YourApp-YourVersion"));
  post.setEntity(reqEntity);
  HttpResponse response = client.execute(post);
  if (response.getStatusLine().getStatusCode() == 200) {
   InputStream input = response.getEntity().getContent();
   String result = IOUtils.toString(input);
   String authToken = getAuthToken(result);
   post = new HttpPost(appUrl + "/_ah/login?auth=" + authToken);
   response = client.execute(post);
   Header[] cookies = response.getHeaders("SET-COOKIE");
   for (Header cookie : cookies) {
    if (cookie.getValue().startsWith("ACSID=")) {
     return cookie.getValue();
    }
   }
   throw new Exception("ACSID cookie cannot be found");
  } else
   throw new Exception("Error obtaining ACSID");
 }
A simple example on how to use it:

String authCookie = logonHelper.loginToGoogle("email@gmail.com",
   "password","http://yourapp.appspot.com");  
DefaultHttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet("http://yourapp.appspot.com/service");
get.setHeader("Cookie", authCookie);
HttpResponse response = client.execute(get);
response.getEntity().writeTo(System.out);