January 2014 – Alex Arriaga

alex-arriaga January 27, 2014

How to print Attributes enumeration in Java (javax naming directory Attributes)

Enterprise Development, Java EE No Reply

This is only a little piece of code to print all the IDs and values of a javax.naming.directory.Attributes.

If you want to know more about this interface, please see official documentation (http://docs.oracle.com/javase/7/docs/api/javax/naming/directory/Attributes.html), but here, you have a little explanation about it:

This interface represents a collection of attributes.
In a directory, named objects can have associated with them attributes. The Attributes interface represents a collection of attributes. For example, you can request from the directory the attributes associated with an object. Those attributes are returned in an object that implements the Attributes interface.

Attributes in an object that implements the Attributes interface are unordered. The object can have zero or more attributes. Attributes is either case-sensitive or case-insensitive (case-ignore). This property is determined at the time the Attributes object is created. (see BasicAttributes constructor for example). In a case-insensitive Attributes, the case of its attribute identifiers is ignored when searching for an attribute, or adding attributes. In a case-sensitive Attributes, the case is significant.

Note that updates to Attributes (such as adding or removing an attribute) do not affect the corresponding representation in the directory. Updates to the directory can only be effected using operations in the DirContext interface.

public void printAttrs(Attributes attrs)
{
    System.out.println(">> printAttrs()");
    if (attrs == null)
    {
        System.out.println("No attributes");
    }
    else
    {
        // Print every single attribute
        try
        {
            for (NamingEnumeration ae = attrs.getAll(); ae.hasMore();)
            {
                Attribute attr = (Attribute) ae.next();
                System.out.println("Attribute ID: " + attr.getID());

                // Print values of current attribute
                NamingEnumeration e = attr.getAll();
                while(e.hasMore())
                {
                    String value = e.next().toString();
                    System.out.println("Value: " + value);
                }
            }
        } catch (NamingException e) { e.printStackTrace(); }
    }
    System.out.println("<< printAttrs()");
}

public void printAttrs(Attributes attrs)

{

System.out.println(">> printAttrs()");

if (attrs == null)

{

System.out.println("No attributes");

}

else

{

// Print every single attribute

try

{

for (NamingEnumeration ae = attrs.getAll(); ae.hasMore();)

{

Attribute attr = (Attribute) ae.next();

System.out.println("Attribute ID: " + attr.getID());

// Print values of current attribute

NamingEnumeration e = attr.getAll();

while(e.hasMore())

{

String value = e.next().toString();

System.out.println("Value: " + value);

}

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

}

System.out.println("<< printAttrs()");

}

That’s it!

Be happy with your code!

alex-arriaga January 27, 2014

How to get a multi-valued LDAP attribute in JAVA (using a custom query to LDAP)

Enterprise Development, Java EE No Reply

Today, I would like to show you an example of a custom query to an LDAP, this query obtains a multi-valued LDAP attribute.

Situation

Imagine you need to know the associated user ids that are linked to an existing user, so you know the name of the LDAP attribute which is “associatedUserID”, and of course you have access to LDAP using a valid user and password.

1) Create a method to run a query to LDAP:

/*
* An example of a method with a query to get a multi-valued attribute
*/
public boolean isUserAssociatedWithAUser(String userID, String associatedUserID){
	DirContext context = null;
    String dn = "";
    try
		{
    		Hashtable env = new Hashtable();
    		env.put(Context.SECURITY_PRINCIPAL, "your_admin_id");      
			env.put(Context.SECURITY_CREDENTIALS, "password_admin");
	     	DirContext initial = new InitialDirContext(env);
	     	context = (DirContext) initial.lookup("server_url");

    		String ou[] = {"department", "network"};

    		for(int i = 0;i < ou.length;i++)
	  	 	{
	     		String base = "userid=" + userID + ",ou=" + ou[i] + ",o=your_domain.com";	// Your custom LDAP query
	    		String filter = "(objectclass=*)";											// Your filter
	    		SearchControls sc = new SearchControls();  
		  	 	sc.setSearchScope(SearchControls.OBJECT_SCOPE);								// Set scope of your search

		  	 	// The LDAP attribute that you are looking for, in this example "associatedUserID" is multi-valued
		  	 	sc.setReturningAttributes(new String[] {"associatedUserID"});			
	    		try 
	    		{
	    			NamingEnumeration answer = context.search(base, filter, sc);
	    			dn = base;

	    			while (answer.hasMore()) 
	    			{
			     		SearchResult sr = (SearchResult) answer.next(); 
			     		Attributes attrs = sr.getAttributes();
			     		List associatedUserIDs = getAssociatedUserIdsFromAttrs(attrs);

			     		for(int j=0; j<associatedUserIDs.size(); j++)
                        {
			     			Object associatedPortalUserID = associatedUserIDs.get(j);
                        	if(associatedPortalUserID instanceof String)
                        	{
                        		String associatedPortalUserIDStr = (String)associatedPortalUserID;
                        		if(associatedPortalUserIDStr.indexOf(associatedUserID) >= 0)
                    			{
                    				dpLogger.info(userID + " is associated with " + associatedPortalUserIDStr);
                    				return true;
                    			}
                        	}
                        }

			     	}// ends while
	     		}
	    		catch (javax.naming.NameNotFoundException e)
	    		{
	    	  		//Do nothing since the user is not in this ou
	    	  	}
	    		// Found 
	    		if (! dn.equals("")){ break;}
	  	 	}
	  	}
	  	catch (javax.naming.CommunicationException e)
		{
	  		System.out.println("Admin Authentication Exception: Could not communicate with user directory.");
	  		return false;
	  	}
	  	catch(Exception e)
		{
	  		System.out.println("An Error occured while trying to Authenticate Admin.");
	  		return false;
	  	}
	  	finally
		{
	  		if ( context != null )
	  		{
	  			try { context.close(); } catch (Exception e) {}
	  		}
		}

	  	//Check if the user ID was found   
	  	if (dn.equals(""))
	  	{
	  		System.out.println("User not found error");
	  		return false;
	  	}
	return false;
}

* An example of a method with a query to get a multi-valued attribute

public boolean isUserAssociatedWithAUser(String userID, String associatedUserID){

DirContext context = null;

String dn = "";

try

{

Hashtable env = new Hashtable();

env.put(Context.SECURITY_PRINCIPAL, "your_admin_id");

env.put(Context.SECURITY_CREDENTIALS, "password_admin");

DirContext initial = new InitialDirContext(env);

context = (DirContext) initial.lookup("server_url");

String ou[] = {"department", "network"};

for(int i = 0;i < ou.length;i++)

{

String base = "userid=" + userID + ",ou=" + ou[i] + ",o=your_domain.com"; // Your custom LDAP query

String filter = "(objectclass=*)"; // Your filter

SearchControls sc = new SearchControls();

sc.setSearchScope(SearchControls.OBJECT_SCOPE); // Set scope of your search

// The LDAP attribute that you are looking for, in this example "associatedUserID" is multi-valued

sc.setReturningAttributes(new String[] {"associatedUserID"});

try

{

NamingEnumeration answer = context.search(base, filter, sc);

dn = base;

while (answer.hasMore())

{

SearchResult sr = (SearchResult) answer.next();

Attributes attrs = sr.getAttributes();

List associatedUserIDs = getAssociatedUserIdsFromAttrs(attrs);

for(int j=0; j<associatedUserIDs.size(); j++)

{

Object associatedPortalUserID = associatedUserIDs.get(j);

if(associatedPortalUserID instanceof String)

{

String associatedPortalUserIDStr = (String)associatedPortalUserID;

if(associatedPortalUserIDStr.indexOf(associatedUserID) >= 0)

{

dpLogger.info(userID + " is associated with " + associatedPortalUserIDStr);

return true;

}

}// ends while

}

catch (javax.naming.NameNotFoundException e)

{

//Do nothing since the user is not in this ou

}

// Found

if (! dn.equals("")){ break;}

}

catch (javax.naming.CommunicationException e)

{

System.out.println("Admin Authentication Exception: Could not communicate with user directory.");

return false;

}

catch(Exception e)

{

System.out.println("An Error occured while trying to Authenticate Admin.");

return false;

}

finally

{

if ( context != null )

{

try { context.close(); } catch (Exception e) {}

}

//Check if the user ID was found

if (dn.equals(""))

{

System.out.println("User not found error");

return false;

}

return false;

}

2) For explaining purposes, I have split the reading operation (using a Attributes enumeration) in another method:

public List getAssociatedUserIdsFromAttrs(Attributes attrs) {
    List associatedUsers = new ArrayList();

   	if (attrs != null)
    {
    	try
    	{
    		for (NamingEnumeration ae = attrs.getAll(); ae.hasMore();)
    		{
    			Attribute attr = (Attribute) ae.next();
    			System.out.println("Attribute ID:" + attr.getID());

                // Obtaining only the associatedUserID attribute's values
    			if(attr.getID().equals("associatedUserID"))
    			{
    				NamingEnumeration e = attr.getAll();
    				while(e.hasMore())
    				{
    					String value = e.next().toString();
    					System.out.println("Value: " + value);
    					associatedUsers.add(value);
                    }
    			}
            }
    	}catch (NamingException e) { e.printStackTrace(); }
    }
    return associatedUsers;
}

public List getAssociatedUserIdsFromAttrs(Attributes attrs) {

List associatedUsers = new ArrayList();

if (attrs != null)

{

try

{

for (NamingEnumeration ae = attrs.getAll(); ae.hasMore();)

{

Attribute attr = (Attribute) ae.next();

System.out.println("Attribute ID:" + attr.getID());

// Obtaining only the associatedUserID attribute's values

if(attr.getID().equals("associatedUserID"))

{

NamingEnumeration e = attr.getAll();

while(e.hasMore())

{

String value = e.next().toString();

System.out.println("Value: " + value);

associatedUsers.add(value);

}

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

}

return associatedUsers;

}

That’s it!

Be happy with your code!

alex-arriaga January 20, 2014

How to create a List from a JSON object in Java using Jackson Library

Enterprise Development, Java EE No Reply

Today, I would like to share an easy way to parse a JSON string into a List of Java objects in a few lines of code. Imagine the situation where you need to create a List of complex objects from a JSON array in Java, for example if we have this kind of input:

[
	{
		"title":"Title of hotspot #1",
		"x":194,
		"y":180,
		"order":0,
		"url":"http://www.alex-arriaga.com/"
	},
	{
		"title":"Title of hotspot #2",
		"x":23,
		"y":45,
		"order":1,
		"url":"http://www.alex-arriaga.com/about-me/"
	}
]

[

{

"title":"Title of hotspot #1",

"x":194,

"y":180,

"order":0,

"url":"http://www.alex-arriaga.com/"

{

"title":"Title of hotspot #2",

"x":23,

"y":45,

"order":1,

"url":"http://www.alex-arriaga.com/about-me/"

}

]

Now, suppose we have following POJO class (this class will have our fields for doing the mapping from JSON to a Java List):

package com.base22.model;

public class HotSpot{
	private String title;
	private int x;
	private int y;
	private int order;
	private String url;

	public HotSpot(){

	}

	// Create more constructors if you want :)

	public int getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public int getX() {
		return x;
	}

	public void setX(int x) {
		this.x = x;
	}

	public int getY() {
		return y;
	}

	public void setY(int y) {
		this.y = y;
	}

	public int getOrder() {
		return order;
	}

	public void setOrder(int order) {
		this.order = order;
	}

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	@Override
	public String toString(){
		StringBuilder sb = new StringBuilder();
		sb.append("\nHotspot [ID=" + id + "]");
		sb.append("\nUrl: " + url);
		sb.append("\nDescription: " + description);
		sb.append("\nOrder: " + order);

		return sb.toString();
	}

}

package com.base22.model;

public class HotSpot{

private String title;

private int x;

private int y;

private int order;

private String url;

public HotSpot(){

}

// Create more constructors if you want :)

public int getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public int getX() {

return x;

}

public void setX(int x) {

this.x = x;

}

public int getY() {

return y;

}

public void setY(int y) {

this.y = y;

}

public int getOrder() {

return order;

}

public void setOrder(int order) {

this.order = order;

}

public String getUrl() {

return url;

}

public void setUrl(String url) {

this.url = url;

}

@Override

public String toString(){

StringBuilder sb = new StringBuilder();

sb.append("\nHotspot [ID=" + id + "]");

sb.append("\nUrl: " + url);

sb.append("\nDescription: " + description);

sb.append("\nOrder: " + order);

return sb.toString();

}

One of the easiest way to reach our goal is by using Jackson library (http://jackson.codehaus.org/), which has a really good mapper. Let me show two single lines to map our JSON input into a Java List.

// This is an example of a JSON input string
String jsonString = "[{\"title\":\"Title of hotspot #1\",\"x\":194,\"y\":180,\"order\":0,\"url\":\"http://www.alex-arriaga.com/\"},{\"title\":\"Title of hotspot #2\",\"x\":23,\"y\":45,\"order\":1,\"url\":\"http://www.alex-arriaga.com/about-me/\"}]";

1 2	// This is an example of a JSON input string String jsonString = "[{\"title\":\"Title of hotspot #1\",\"x\":194,\"y\":180,\"order\":0,\"url\":\"http://www.alex-arriaga.com/\"},{\"title\":\"Title of hotspot #2\",\"x\":23,\"y\":45,\"order\":1,\"url\":\"http://www.alex-arriaga.com/about-me/\"}]";

try{
	ObjectMapper jsonMapper = new ObjectMapper();
	List <HotSpot> hotspots = jsonMapper.readValue(jsonString, new TypeReference<List<HotSpot>>(){});
}catch(Exception e){
	e.printStackTrace();
}

try{

ObjectMapper jsonMapper = new ObjectMapper();

List <HotSpot> hotspots = jsonMapper.readValue(jsonString, new TypeReference<List<HotSpot>>(){});

}catch(Exception e){

e.printStackTrace();

}

Finally, you could iterate among all the objects in your new List.

for(HotSpot hotspot : hotspots){
	System.out.println(hotspot);
}

for(HotSpot hotspot : hotspots){

System.out.println(hotspot);

}

That’s it!

Be happy with your code!

alex-arriaga January 17, 2014

How to set no-cache headers in a Java EE application’s response (using a Spring controller)

Enterprise Development, Java EE No Reply

Sometimes when you do a request to a Java service you will need to add some custom headers in the response, for example, today I was creating a service to get the current logged user data and I realized one client was storing (creating a cache) the response and sometimes the service was not working as expected.

So, in my case I was using Spring MVC to create a custom XML response I wanted to add a no-cache header, for that reason I spent some time to figure out which is the right way to do it, please let me explain how you can do that easily!

1) Following is an example of a Java method that contains Spring and JAXB annotations to create a custom XML and set custom headers in the response:

	@RequestMapping(method ={RequestMethod.GET, RequestMethod.POST}, produces="application/xml")
	public @ResponseBody UserProfileResponse getUserProfileInXML(HttpServletRequest request, HttpServletResponse response) {

		// UserProfileResponse and UserProfileService are MY custom classes, but you can retrieve any class you want!
		UserProfileResponse profileResponse = new UserProfileResponse();
		UserProfileService service = UserProfileService.getInstance();	// A singleton class
		Principal principal = (Principal) request.getUserPrincipal();

		if (principal != null) {
			profileResponse.setUserProfile( service.getUserProfile(principal.getName()) );
		}

		// Setting response's headers
		response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
		response.setHeader("Pragma", "no-cache"); // HTTP 1.0.
		response.setDateHeader("Expires", 0); // Proxies.

		return profileResponse;
	}

@RequestMapping(method ={RequestMethod.GET, RequestMethod.POST}, produces="application/xml")

public @ResponseBody UserProfileResponse getUserProfileInXML(HttpServletRequest request, HttpServletResponse response) {

// UserProfileResponse and UserProfileService are MY custom classes, but you can retrieve any class you want!

UserProfileResponse profileResponse = new UserProfileResponse();

UserProfileService service = UserProfileService.getInstance(); // A singleton class

Principal principal = (Principal) request.getUserPrincipal();

if (principal != null) {

profileResponse.setUserProfile( service.getUserProfile(principal.getName()) );

}

// Setting response's headers

response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.

response.setHeader("Pragma", "no-cache"); // HTTP 1.0.

response.setDateHeader("Expires", 0); // Proxies.

return profileResponse;

}

2) The important lines in previous code are:

// Setting response's headers
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
response.setHeader("Pragma", "no-cache"); // HTTP 1.0.
response.setDateHeader("Expires", 0); // Proxies.

// Setting response's headers

response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.

response.setHeader("Pragma", "no-cache"); // HTTP 1.0.

response.setDateHeader("Expires", 0); // Proxies.

Because they set custom response’s headers to establish a no-cache configuration.

3) Now, just to test we could do a normal request in a browser and we can see the headers:

As you can see, the headers were set correctly.

That’s it!

Be happy with your code!

alex-arriaga January 7, 2014

Setting UTF-8 encoding in a JSP (changing ISO-8859-1 to UTF-8 on IBM Rational Application Developer)

Enterprise Development, Java EE 2 Replies

Today, I was integrating a custom JSP component into IBM WCM and I noticed some characters were not displaying as expected, after looking into the generated source code in Firefox I realized the used encoding was ISO-8859-1, let me explain what ISO-8859-1 means…

According the W3C the ISO-8859-1 encoding:

ISO-8859-1 is the default character set in most browsers.

The first 128 characters of ISO-8859-1 is the original ASCII character-set (the numbers from 0-9, the uppercase and lowercase English alphabet, and some special characters).

The higher part of ISO-8859-1 (codes from 160-255) contains the characters used in Western European countries and some commonly used special characters.

Entities are used to implement reserved characters or to express characters that cannot easily be entered with the keyboard.

My source code looked like this (in Firefox):

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />

1	<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />

And this was the displayed characters (look the “Spanish”, “Portuguese” and “Russian” language labels):

Well, solution for this enconding error is really easy, we only need to:

1) Set the encoding in the JSP file (using your editor or IDE), in my case I was using Rational:

2) Type a directive to indicate we WANT to use UTF-8. At the beginning of your JSP code add following line:

<%@page language="java" contentType="text/html; charset=utf-8" %>

1	<%@page language="java" contentType="text/html; charset=utf-8" %>

That’s it! now all our messages will be ok 🙂

Be happy with your code!

What would you like to know about?

Alex Arriaga

Monthly Archives:
January 2014

How to print Attributes enumeration in Java (javax naming directory Attributes)

How to get a multi-valued LDAP attribute in JAVA (using a custom query to LDAP)

Situation

How to create a List from a JSON object in Java using Jackson Library

How to set no-cache headers in a Java EE application’s response (using a Spring controller)

Setting UTF-8 encoding in a JSP (changing ISO-8859-1 to UTF-8 on IBM Rational Application Developer)

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What would you like to know about?

Monthly Archives: January 2014

Situation

Join me, have fun and learn!

Tag Cloud

Recent Posts

Recent Comments

Join me, have fun and learn!

Recent Posts

Day quote…

Recent Comments

Categories

Tag Cloud

Archives

Join me, have fun and learn!

Recent Posts

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Tag Cloud

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Categories

Monthly Archives:
January 2014