Single Responsibility Principle / Separation of Concerns (SoC) / Encapsulation / Information Hiding / Principle of Least Privilege / Law of Demeter (LoD)
Don't Repeat Yourself (DRY) / Copy-and-Paste Programming / Once And Only Once (OAOO)
Coupling / Composition vs. Inheritance / Inversion of Control (IoC)
Big Requirements/Design Up Front (BRUF/BDUF) / Analysis Paralysis / You Aren't Gonna Need It (YAGNI) / Technical Debt
UnaryOperator bind ( final BinaryOperator binOp, final Object boundLeftArg) {See: http://c2.com/cgi/wiki?JavaFinalArguments
return new UnaryOperator() {
public Object apply(Object arg) {
return binOp.apply(boundleftArg, arg);
}
};
}
What should be the preferred choice for O/R mapping...?
See: The EJB 3.0 Hibernate Fallacy
These frameworks provide similarly common features:
EntityManager - A transaction-level artifact that references, maintains identity and manages the objects in a given transaction. JDO calls this a PersistenceManager, Hibernate calls this a Session. TopLink calls this a UnitOfWork. These are all very close in scope, purpose and API.
Named queries - Queries must be able to be pre-defined and bound to a name for later retrieval and execution. These are called named queries in all of TopLink, Hibernate and JDO.
Native queries - Native SQL queries that allow the application to specify the query criteria in SQL. These are called SQL queries in all of TopLink, Hibernate and JDO.
Callback Listeners - The ability to define a class or method that will get invoked when a given event occurs. TopLink calls these event listeners, Hibernate and JDO call them life cycle callbacks.
Detaching/Reattaching objects - Objects can leave the scope of the EntityManager that controls them. They can also be reattached to the same or a different EntityManager through the use of the merge API call on the EntityManager. TopLink offers a series of merge calls, the most basic one being mergeClone. Hibernate has saveOrUpdateCopy and JDO has a couple of flavours of attachCopy call on the PersistenceManager.
O/R Mapping Types - All of the direct and relationship mapping types that are fundamental to mapping object state to relational database tables. These are all supported by Hibernate, TopLink and JDO. I won't go through all of the names (one-to-one, etc.. they are all pretty standard), but although some of the names differ a little bit from one to the other the functionality is pretty much the same and what you would expect.
Embedded Objects - Objects that have no persistent identity of their own but depend upon their parent object for identity. JDO calls them embedded objects, TopLink calls them aggregates and Hibernate calls them components.
public static<T> void copy(
Box<? extends T> from,
Box<? super T> to) {
to.put(from.get());
}
/**
* Typical DAO/Service layer finder method.
* If unable to find the Object from the ID,
* throw an Exception instead of returning null.
*/
public Object findById(BigDecimal id)
throws NotFoundException, FindException {
try {
ResultSet resultSet = preparedStatement.executeQuery();
if (resultSet.next()) {
Object obj = new Object();
// populate the object...
return obj;
}
// throw a runtime exception instead of returning a null object
throw new NoSuchElementException("Object not found for ID: " + id);
} catch (SQLException e) {
throw new FindException(e);
}
}
/**
* Template for a Utils class full of Static methods.
* Declare the class as Final so it cannot be subclassed.
*/
public final class MyUtils {
/**
* Provide a Private constructor to prevent instantiation.
*
* Use Assertions (if enabled) or throw an Error in case of
* an attempt is made to instantiate within the class itself.
*/
private MyUtils() {
assert false;
// OR
throw new AssertionError();
}
}
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration PUBLIC "http://logging.apache.org/log4j/docs/api/org/apache/log4j/xml/log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<!-- an appender is an output destination, such as e.g. the console or a file;
names of appenders are arbitrarily chosen -->
<appender name="stdout" class="org.apache.log4j.ConsoleAppender">
<!-- layouts are used by appenders to format layout -->
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"value="%d{ABSOLUTE} %5p %c{1}:%L - %m%n" />
</layout></appender>
<appender name="debug" class="org.apache.log4j.FileAppender">
<param name="File" value="logs/debug.log" />
<param name="Threshold" value="debug" />
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%d{ISO8601} %-5p %c - %m%n"/>
</layout>
</appender>
<!-- the root category --><root>
<!-- all|debug|info|warn|error|fatal|off|null -->
<!-- all log messages of level debug or more serious will be logged, unless defined otherwise -->
<priority value="debug" />
<appender-ref ref="stdout" />
<appender-ref ref="debug"/>
</root>
</log4j:configuration>
/**
* @return the log.
*/
protected Log getLog() {
if (this.log == null) {
this.log = LogFactory.getLog(this.getClass());
}
return this.log;
}
if (getLog().isInfoEnabled())
getLog().info("Hello World!");
"A set of specifications which describe a model for building applications and systems using a Service-Oriented Architecture. SCA extends and complements prior approaches to implementing services, and SCA builds on open standards such as Web services."
Concepts:
Supported by BEA, IBM, Oracle, SAP AG, Red Hat, Sun, TIBCO and others.
Implementations:
Also a class which complies with the following:
Key Concepts:
JSR 311: JAX-RS: The JavaTM API for RESTful Web Services
Implementing RESTful Web Services in Java
// create cookies
HttpServletResponse httpServletResponse =
(HttpServletResponse)FacesContext.getCurrentInstance().getExternalContext().getResponse();
Cookie cookie = new Cookie("cookieKey", "cookieValue");
cookie.setMaxAge(365);
cookie.setComment("A Comment");
httpServletResponse.addCookie(cookie);
// get cookies
HttpServletRequest httpServletRequest =
(HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
Cookie[] cookies = httpServletRequest.getCookies();
if (cookies != null) {
for(int i=0; i<cookies.length; i++){
if (cookies[i].getName().equalsIgnoreCase("cookieKey")){
String cookieValue = cookies[i].getValue();
}
}
}
import java.util.HashSet;
import java.util.Set;
import javax.faces.context.FacesContext;
import javax.security.auth.login.AccountExpiredException;
import javax.security.auth.login.CredentialExpiredException;
import javax.security.auth.login.FailedLoginException ;
import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import com.ibm.websphere.security.auth.callback.WSCallbackHandlerImpl;
import uk.org.gth.exceptions.LoginException;
public class LoginUtils {
public static void doLogin(String username, String password, FacesContext facesContext)
throws LoginException {
LoginContext loginContext = null;
try {
loginContext = new LoginContext("WSLogin", new WSCallbackHandlerImpl(username, password));
loginContext.login();
} catch (AccountExpiredException e) {
throw new LoginException("Account has Expired.");
} catch (CredentialExpiredException e) {
throw new LoginException("Credentials have Expired.");
} catch (FailedLoginException e) {
throw new LoginException("Login Failure.");
} catch (LoginException e) {
if (e.getMessage().indexOf("52e") > 0) {
throw new LoginException("Invalid Password.");
} else if (e.getMessage().indexOf("532") > 0) {
throw new LoginException("Password Has Expired.");
} else if (e.getMessage().indexOf("533") > 0) {
throw new LoginException("Your account has been disabled.");
} else if (e.getMessage().indexOf("701") > 0) {
throw new LoginException("Your account has expired.");
} else if (e.getMessage().indexOf("773") > 0) {
throw new LoginException("Your password must be reset.");
} else {
throw new LoginException(e.getMessage());
}
} catch (SecurityException e) {
throw new LoginException("Cannot create LoginContext.");
}
}
}