Презентация на тему Spring Framework

to program to interfaces, rather than classes. Spring reduces

the complexity cost of using interfaces to zero.

JavaBeans offer a great way of configuring applications.

OO design is more important than any implementation technology, such as J2EE.

Checked exceptions are overused in Java. A framework shouldn't force you to catch exceptions you're unlikely to be able to recover from.

Testability is essential, and a framework such as Spring should help make your code easier to test.

comprehensive infrastructure support for developing Java applications. Spring handles

the infrastructure so you can focus on your application.

Spring enables you to build applications from “plain old Java objects” (POJOs) and to apply enterprise services non-invasively to POJOs. This capability applies to the Java SE programming model and to full and partial Java EE.

and overhead. The entire Spring framework can be distributed

in a single JAR file that weighs in at just over 1 MB. And the processing overhead required by Spring is negligible. What’s more, Spring is nonintrusive: objects in a Spring-enabled application typically have no dependencies on Spring specific classes.

Inversion of control—Spring promotes loose coupling through a technique known as inversion of control (IoC). When IoC is applied, objects are passively given their dependencies instead of creating or looking for dependent objects for themselves.

Aspect-oriented - Spring comes with rich support for aspect-oriented programming that enables cohesive development by separating application business logic from system services (such as auditing and transaction management). Application objects do what they’re supposed to do—perform business logic—and nothing more. They are not responsible for (or even aware of) other system concerns, such as logging or transactional support.

Container - Spring is a container in the sense that it contains and manages the life cycle and configuration of application objects. You can configure how your each of your beans should be created—either create one single instance of your bean or produce a new instance every time one is needed based on a configurable prototype—and how they should be associated with each other.

Framework - Spring makes it possible to configure and compose complex applications from simpler components. In Spring, application objects are composed declaratively, typically in an XML file. Spring also provides much infrastructure functionality (transaction management, persistence framework integration, etc.), leaving the development of application logic to you.

I'll call you

“Container” resolves (injects) dependencies of components by

setting implementation object (push)

As opposed to component instantiating or Service Locator pattern where component locates implementation (pull)

Martin Fowler calls Dependency Injection

IOrderDAO orderDAO = new OrderDaoImpl();

public Order saveOrder(Order order) throws

OrderException{
try{
orderDao.saveOrder(order);
}catch(Exception e){
// handle e, rollback transaction, //cleanup, // throw e
}finally{
//Release resources and handle more exceptions
}
}

IOrderDAO orderDAO ;

public OrderServiceImpl (IOrderDAO orderDAO) {
this.orderDAO = orderDAO;
}

public

void setOrderDAO (IOrderDAO orderDAO) {
this.orderDAO = orderDAO;
}

public Order saveOrder(Order order) throws OrderException{
try{
orderDao.saveOrder(order);
}catch(Exception e){
// handle e, rollback transaction, //cleanup, // throw e
}finally{
//Release resources and handle more exceptions
}
}

valueOf);
}



package org.lesson7.bean;

public class Printer implements IPrinter {

private String message;

public

void setMessage(String message) {
this.message = message;
}

public void printMessage() {
System.out.println("Your Message : " + message);
}
}

Double value;

public IPrinter getPrinter() {
return printer;
}

public void setPrinter(IPrinter printer)

{
this.printer = printer;
}

public void set(Double val) {
this.value = val;
}

public void print() {
printer.setMessage(String.valueOf(this.value));
printer.printMessage();
}
}

class="org.lesson7.bean.Printer">

/>

args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
new String[] {"beans.xml"});
Printer bean

= context.getBean("printer", Printer.class);
bean.printMessage();

Container container = context.getBean("container", Container.class);
container.set(1234d);
container.print();

System.out.println(bean == container.getPrinter());
}
}

{ … }


@Service
public class Container { … }


Step 2.
@Service
public

class Container {

private IPrinter printer;
private Double value;

@Autowired
public void setPrinter(IPrinter printer) {
this.printer = printer;
}

context = new ClassPathXmlApplicationContext(
"beans-annot.xml");

Container container = context.getBean("container", Container.class);
container.set(1234d);
container.print();
}

controller classes

@Repository – DAO classes

property must be populated at configuration time: either through

an explicit property value in a bean definition or through autowiring. The container will throw an exception if the affected bean property has not been populated.



public class SimpleMovieLister {
private MovieFinder movieFinder;

@Required
public void setMovieFinder(MovieFinder movieFinder) {
this.movieFinder = movieFinder;
}
}

= printer;
}

3. Setter
@Autowired
public void setPrinter(IPrinter printer) {
this.printer = printer;
}

printer;

5. Well-known "resolvable dependencies“
@Autowired
private ApplicationContext context;

candidates, it is often necessary to have more control

over the selection process. One way to accomplish this is with Spring's @Qualifier annotation.

@Autowired
@Qualifier("main")
private MovieCatalog movieCatalog;


@Autowired
public void prepare(@Qualifier("main") MovieCatalog movieCatalog,
CustomerPreferenceDao customerPreferenceDao) {
this.movieCatalog = movieCatalog;
this.customerPreferenceDao = customerPreferenceDao;
}

5 Common Annotations (JSR-250). The supported annotations are:

@Resource
@PostConstruct
@PreDestroy

@Resource(name =

"dataSource")
public void createTemplate(DataSource dataSource) {
this.jdbcTemplate = new SimpleJdbcTemplate(dataSource);
}

public class CachingMovieLister {
@PostConstruct
public void populateMovieCache() {… }

@PreDestroy
public void clearMovieCache() {… }
}

to modularize cross-cutting concerns in aspects.

Put it simple,

it’s just an interceptor to intercept some processes, for example, when a method is execute, Spring AOP can hijack the executing method, and add extra functionality before or after the method execution.

technical terms – Advice, Pointcut, Advisor:

Advice – Indicate the

action to take either before or after the method execution.

Pointcut – Indicate which method should be intercept, by method name or regular expression pattern.

Advisor – Group ‘Advice’ and ‘Pointcut’ into a single unit, and pass it to a proxy factory object.

are supported :

Before advice – Run before the method

execution

After returning advice – Run after the method returns a result

After throwing advice – Run after the method throws an exception

After (finally) advice – Run after normal or exceptional return

Around advice – Run around the method execution, combine all three advices above.

void log() {
}

@Around("log()")
public Object profile(ProceedingJoinPoint pjp) throws Throwable {
MethodSignature

signature = (MethodSignature) pjp.getSignature();
Method method = signature.getMethod();
long start = System.currentTimeMillis();
System.out.println("Going to call the method: " + method.getName());

Object output = pjp.proceed();

System.out.println("Method execution completed.");
long elapsedTime = System.currentTimeMillis() - start;
System.out.println("Method execution time: " + elapsedTime
+ " milliseconds.");
return output;
}