Springboot: controller access files through Resource Interface

Access files through classpath.

Springboot will  scan /META-INF/resources/; /resources/; /static/ and/public/ folders when you tell it find something in the “Classpath”. 

Using Resource interface to instantiate an ClassPathResource. 

		Resource resource =new ClassPathResource("RelativePathOfYourFile, root of  /META-INF/resources/; /resources/; /static/ or /public/");
		
		try {
			String path =resource.getFile().getAbsolutePath();
			
		} catch (IOException e) { 
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

Fix delete()function

Let’s have a look on the code in DataStore class (in the core).

 /**
         * Deletes the given object and returns the object if successful
         * @param The object to be deleted
         * @return The object being deleted
         */
        public <T> T delete(T aTNG){
                // Please see Wiki for more information on the ServerConfiguration.
                ClientConfiguration config = Db4oClientServer.newClientConfiguration();
                config.common().reflectWith(new JdkReflector(Thread.currentThread().getContextClassLoader()));

                logger.log(Level.FINE, "Database Delete Attempt...");
                //ObjectContainer client = server.openClient();
                ObjectSet<T> result = theDB.queryByExample(aTNG);
                T found = (T) result.next(); //<--- will send out exception:java.lang.IllegalStateException
                                                             //if "result" is empty.
                theDB.delete(found);
                theDB.commit();

                logger.log(Level.FINE, "Database Delete Success!");
                //return "Deleted "+aTNG;
                return found;

        }

Problem Analysis: 

In this term, many groups used Calendar object to store date information. However, it seems that calendar(or say GregorianCalendar) cannot be parsed and compared in db4o database.This makes queryByExample() method cannot locate the data we find. So if we pass a commitment, which we wanna delete from the database, to this method the  ObjectSet<T> result = theDB.queryByExample(aTNG);, it cannot find the one in the database and return an empty result collection. Then when we use .next() method on an empty collection, we will get errors. This is the reason why we pass the thing we wanna delete to the database, and the database can’t delete it and give us an error.

Solution: 

Since CalendarItem have a unique id. We just make a null CalendarItem(eg. CalendarItem(null,null,null)) and set it’s id to the one we wanna delete, and pass it to the delete method in the DataStore.

e.g:

public boolean deleteEntity(Session s, String id) throws WPISuiteException{

ensureRole(s, Role.ADMIN);

Commitment oldComm = new Commitment(null,null,null);

oldComm.setId(Integer.parseInt(id));

Commitment deletedComm = db.delete(oldComm);

if (deletedComm != null){

System.out.println("Here is deletEntity method. ---> delete Succesfull");

return true; // the deletion was successful

}   

System.out.println("Here is deletEntity method. ---> delete Fail");

return false; // The deletion was unsuccessful

}

 

Details:

1.queryByExample is the same as get() (deprecated) method  in the db4o.

Reference: http://www.db4o.com/about/productinformation/resources/db4o-6.3-tutorial-java.pdf

CSS基本笔记(CSS Memo)

1. Reasons to use CSS: DRY, Clean

Examles: 1.

<h1 style="color: #98c7d4;"> Hellow World! </h1>
2.
<head>
<style>
h1 { color: #98c7d4; }
</style>
</head>

This two way maybe will repeat numerous times, so the paragraph of code will be large. The best way is making a External sheet in the following way:

<head>
<title>CSS Cross Country</title>
<link rel="stylesheet" href="styles.css" />
</head>

This will make your codes DRY(Don’t Repeat Yourself)


2.Cascade Order(something about the code priority)

 

Using !important < Inline style arttribute  < In the <head>  < External <link>

 


3.Primary DOM selectors

Example:

<h1 class="intro" id="header">Hello World!</h1>

-Element selector
h1{
 color:#aba4ac;
 margin-bottom:10px;
}
-Class selector
.intro{
  color:#abc4ac;
  margin-bottom:10px;
}
-ID selector
#header{
  color:#abc4ac;
  margin-bottom:10px;
}

4.Float <float: left/right/none;>

when we put pictures and paragraphs in a container, we could us Float to deal with their relation.

*Floated elements stack up to the parent edge, then move down to the next available edge. 

*Take care with elements that have differing heights-the first available edge isn’t always below.

 

Clearfix

/*Originally developed by Tony Aslett and Refined by Nicholas Gallagher */
.group:before
.group:after{
  content:"";
  display:table;
}
.group:after{
  clear:both;
}
.group{
  zoom:1;/*IE6&7*/
}

 

5. Inheritance & Specificity

Override parent properties: nested selector

    0      ,0     ,0     ,0

inline style     #if ID       #of class   #of element

 

 6.BOX

Total box width = content width + padding width +border width

 

Box overflow:

overflow: visible /auto/hidden /scroll

↑when content beyond the container boundaries;

 

Positioning:<position: static/relative/absolute/fixed;>

 

Z-index:

z-index:1;

↑Overlaping

Example:

<article>

  <img class="Green" src="Green.jpg" alt="Ski!"/>

  <img class="sled" src="sled.jpg" alt="Sled!"/>

</article>
.Green, .Brown{

  z-index:1;

}
.Brown{

  z-index:1;

}

In these case the Brown class should be above the Green class

 

7. Display Types:<display: block/inline/inline block;>

block:<div><p><ul><ol><li>

inline:<span><a><em><img>

 

8.Horizontal Centering

In block level:

margin: 0 auto;

in inline block level:

text-align:center;

 

9. Image Cropping

Solutions:

Overflow:hidden;

Or we could

.cropping img {

  height: 300px;

  width:auto;

}