Here is a slightly more interesting Java 8 example. The larger problem being solved involves several smaller needs.
- Finding a users active directory group memberships that match an application specific pattern
- Extracting an organizational "short name" from the group definitions
- Returning a list of official organizational ID's associated with the short names.
Described in a little more detail; if you had a user that belonged to the AD groups like:
CN=HapBu-WidgetMaint-App-Employee-Role,OU=Security,OU=Groups.DC=TESTORG,DC=ORG
CN=ChkSk-WidgetMgr-App-Employee-Role,OU=Security,OU=Groups.DC=TESTORG,DC=ORG
CN=Other-App-Role,OU=Security,OU=Groups.DC=TESTORG,DC=ORG
You want to select the first 2 roles because they contain:
App-Employee-Role,OU=Security,OU=Groups
which would be the first 2 items. From those, you want to take the "friendly org name" which would be the values "HapBu" and "ChkSk" and map those to an organization # by using an enum of valid organizations which maintains the mapping.
In the past this would probably require some fairly specific dedicated classes/methods. I found that I am able to do this in a simpl fashion in Java 8. I won't say that it was especially fast for me to develop this but I think over time it will become easier and more natural.
This enumeration, OrganizationInfo, is simply showing the use of a lambda if defining an a method which uses alternative key type info to search/select an enum value.
package test2;
import java.util.Arrays;
import java.util.function.Predicate;
public enum OrganizationInfo
{
HAPPYBURGER("O123", "HapBu"),
TONYTORTILLA("O543", "TonTo"),
CHICKENSHACK("O443", "ChkSk");
OrganizationInfo(final String orgCode,
final String displayableName)
{
this.orgCode = orgCode;
this.displayableName = displayableName;
}
String getOrgCode()
{
return orgCode;
}
/* This is a pretty generic method to select an enum
* value based on some attribute. For this example,
* it is a bit overkill but in a more realistic context this
* allows a good amount of code reuse.
*/
private static OrganizationInfo search(
final Predicate<OrganizationInfo> predicate)
{
// This filters the enum list by the provided predicate and
// returns the first match.
return Arrays.asList(
OrganizationInfo.values()).
stream().
filter(predicate).
findFirst().
get();
}
public static OrganizationInfo displayableNameToEnum(
final String displayableName)
{
// This is example client code to the previous private method and
// demonstrates using a lambda to specify the filter predicate
return search(p -> p.displayableName.equals(displayableName));
}
private String orgCode;
private String displayableName;
}
The getMultValAttrib method is a good example of what code looks like which receives the lambda.
package test2;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;
public class User
{
/**
Responsible for querying multi-valued attribute data from
Active Directory for attribute "attribName", only process
items matching the predicate and then return values
as processed by the provided mapper function.
*/
public List<String> getMultValAttrib(final String attribName,
final Predicate<String> predicate,
final Function<String, String> mapper)
{
List<String> data = Collections.emptyList();
// Get the data from active directory; skipping
// the real details here. Using some dummy data.
final String [] attributeData =
{
"CN=HapBu-WidgetMaint-App-Employee-Role,OU=Security,OU=Groups.DC=TESTORG,DC=ORG",
"CN=ChkSk-WidgetMgr-App-Employee-Role,OU=Security,OU=Groups.DC=TESTORG,DC=ORG"
};
//adctx.getStringAttributes(attribName);
if (attributeData != null)
{
// This is where all the processing is actually done but
// note that the processing functions are passed in so this
// method is pretty generic.
data = Arrays.asList(attributeData). // stream uses a list
stream().
filter(predicate). // Filter out only what we want to keep
map(mapper). // Perform some caller specific mapping
collect(Collectors.toList()); // Produce a list of results
}
return data;
}
}
Below is an example of the above in use.
package test2;
import java.util.List;
public class Test2
{
public static void main(String args[])
{
User aUser = new User();
//....
//...
List<String> orgCodes =
aUser.getMultValAttrib(
"memberOf",
p -> p.matches("(.*App-Employee-Role,OU=Security,OU=Groups.*)"),
g -> OrganizationInfo.displayableNameToEnum(
g.substring(3, g.indexOf('-'))).
getOrgCode());
for(String org: orgCodes)
{
System.out.println(org);
}
}
}
The above code produces the following output:
O123
O443
