guice-servlet

1. guice‐servlet
‐enhanced servlet for Guice‐
May 13th, 2009

2. introduction
Name
Masaaki Yonebayashi
ID
id:yone098
Blog
http://d.hatena.ne.jp/yone098/
Company
Abby Co.,Ltd. President

3. Agenda
What is Guice?
Feature of Guice
Guice Tips
Guice with Google App Engine
What is guice‐servlet?
Feature of guice‐servlet

4. Guice
What is Guice?

5. What is Guice?
Guice 1.0 User’s Guide
Guice is an ultra‐lightweight, next‐
generation dependency injection
container for Java 5 and later.
URL
http://code.google.com/p/google‐guice/
Project owner
crazyboblee, kevinb9n, limpbizkit
Release
2007‐03‐08 1.0 released

6. Download contents
Guice 1.0 Download contents
needs JDK for Java 5 or above
File description
guice‐1.0.jar The core Guice framework
guice‐servlet‐1.0.jar Web‐related scope addition
guice‐spring‐1.0.jar Binding Spring beans
guice‐struts2‐plugin‐ Plugin to use Guice as the
1.0.jar DI engine for Struts2
aopalliance.jar AOP Alliance API, needed to
use Guice AOP

7. Guice
Feature of Guice

8. Feature of Guice
All the DI settings can be
described by Java.
The injection and scope setting are
easy.
The unit test is easy.
Results(Google Adwords)

9. Injection style
Guice Injection styles
Injection Locaion example
order
Constructor public class Ex {
1
@Inject
public Ex(AaService aaService){…}
}
@Inject
2 Field
private BbService bbService;
@Inject
3 Setter
public void setCcService(
CcService ccService){…}

10. Injection setting
Module(settings by Java)
class SampleModule extends AbstractModule {
@Override
protected void configure() {
bind(Service.class).to(ServiceImpl.class);
}
}

11. Injection setting
Module(settings by Java)
class SampleModule extends AbstractModule {
@Override
If you don’t set it
protected void configure() {
bind(Service.class).to(ServiceImpl.class);
}
}

12. Injection setting
ConfigurationException :(
com.google.inject.ConfigurationException:
Error at
samples.Client.<init>(Client.java:20)
Binding to samples.Service not found.
No bindings to that type were found.

13. Injection setting
ConfigurationException :(
com.google.inject.ConfigurationException:
Error at
samples.Client.<init>(Client.java:20)
Binding to samples.Service not found.
No bindings to that type were found.
demo

14. Guice Scope
SINGLETON
Scopes.SINGLETON
Default
Prototype
Guice returns a new instance each
time it supplies a value.

15. Scope setting
setting(default scope)
class SampleModule extends AbstractModule {
@Override
protected void configure() {
bind(Service.class).to(ServiceImpl.class);
}
}

16. Scope setting
setting(SINGLETON scope)
class SampleModule extends AbstractModule {
@Override
protected void configure() {
bind(Service.class).to(ServiceImpl.class)
.in(Scopes.SINGLETON);
}
}

17. Scope setting
setting(SINGLETON scope)
class SampleModule extends AbstractModule {
@Override
protected void configure() {
bind(Service.class).to(ServiceImpl.class)
.in(Scopes.SINGLETON);
}
}
demo

18. Guice
break time

19. Question
Choosing Between Implementations
public interface Pet {
String name();
void run();
}
public class Cat implements Pet { public class Dog implements Pet {
public String name() { public String name() {
return quot;Catquot;; return “Dogquot;;
} }
public void run() { public void run() {
System.out.println(quot;Cat is runquot;); System.out.println(“Dog is runquot;);
} }
} }

20. Question
Choosing Between Implementations
public class Person {
@Inject
private Pet pet;
public void runWithPet() {
this.pet.run();
}
}

21. Question
Choosing Between Implementations
Public static void main(String[] args) {
Injector injector = Guice.createInjector(new AbstractModule() {
@Override
protected void configure() {
bind(Pet.class).to(Dog.class);
bind(Pet.class).to(Cat.class);
}
});
Person person = injector.getInstance(Person.class);
person.runWithPet();
}

22. Answer
CreationException :(
Exception in thread quot;mainquot;
com.google.inject.CreationException: Guice configuration
errors:
1) Error at
samples.GuicePetSample$1.configure(GuicePetSample.java:16
):
A binding to samples.Pet was already configured at
samples.GuicePetSample$1.configure(GuicePetSample.java:15
).

23. Answer
CreationException :(
Exception in thread quot;mainquot;
com.google.inject.CreationException: Guice configuration
errors:
1) Error at
samples.GuicePetSample$1.configure(GuicePetSample.java:16
):
A binding to samples.Pet was already configured at
samples.GuicePetSample$1.configure(GuicePetSample.java:15
).
demo

24. Guice
solves it

25. method 1
Using @Named
public class Person {
@Inject
@Named(“pochi”)
private Pet pet;
public void runWithPet() {
this.pet.run();
}
}

26. method 1
Using @Named
Public static void main(String[] args) {
Injector injector = Guice.createInjector(new AbstractModule() {
@Override
protected void configure() {
bind(Pet.class).annotatedWith(Names.name(“pochi”))
.to(Dog.class);
bind(Pet.class).to(Cat.class);
}
});
Person person = injector.getInstance(Person.class);
person.runWithPet();
}

27. method 1
Using @Named
Public static void main(String[] args) {
Injector injector = Guice.createInjector(new AbstractModule() {
@Override
protected void configure() {
bind(Pet.class).annotatedWith(Names.name(“pochi”))
.to(Dog.class);
bind(Pet.class).to(Cat.class);
}
});
Person person = injector.getInstance(Person.class);
person.runWithPet();
}
demo

28. Guice
another way

29. method 2
Using Biding Annotation
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD,
ElementType.PARAMETER})
@BindingAnnotation
public @interface Pochi {}

30. method 2
Using Biding Annotation
public class Person {
@Inject
@Pochi
private Pet pet;
public void runWithPet() {
this.pet.run();
}
}

31. method 2
Using Biding Annotation
Public static void main(String[] args) {
Injector injector = Guice.createInjector(new AbstractModule() {
@Override
protected void configure() {
bind(Pet.class).annotatedWith(Pochi.class)
.to(Dog.class);
bind(Pet.class).to(Cat.class);
}
});
Person person = injector.getInstance(Person.class);
person.runWithPet();
}

32. method 2
Using Biding Annotation
Public static void main(String[] args) {
Injector injector = Guice.createInjector(new AbstractModule() {
@Override
protected void configure() {
bind(Pet.class).annotatedWith(Pochi.class)
.to(Dog.class);
bind(Pet.class).to(Cat.class);
}
});
Person person = injector.getInstance(Person.class);
person.runWithPet();
}
demo

33. Guice
Guice Tips

34. Guice Tips
Debug Logging, create class
public class GuiceDebug {
private static final Handler HANDLER = new ConsoleHandler() {{
setLevel(Level.ALL); setFormatter(new Formatter() {
public String format(LogRecord r) {
return String.format(“[Debug Guice] %s%nquot;, r.getMessage());
}
});
}};
private GuiceDebug() {}
public static void enable() {
Logger guiceLogger = Logger.getLogger(quot;com.google.injectquot;);
guiceLogger.addHandler(GuiceDebug.HANDLER);
guiceLogger.setLevel(Level.ALL);
}
}

35. Guice Tips
Using GuiceDebug
Public static void main(String[] args) {
GuiceDebug.enable();
Injector injector = Guice.createInjector(new AbstractModule() {
@Override
protected void configure() {
bind(Pet.class).to(Cat.class);
}
});
Person person = injector.getInstance(Person.class);
person.runWithPet();
}

36. Guice Tips
console
[Debug Guice] Configuration: 32ms
[Debug Guice] Binding creation: 47ms
[Debug Guice] Binding indexing: 0ms
[Debug Guice] Validation: 109ms
[Debug Guice] Static validation: 0ms
[Debug Guice] Static member injection: 0ms
[Debug Guice] Instance injection: 0ms
[Debug Guice] Preloading: 0ms

37. Guice Tips
console
[Debug Guice] Configuration: 32ms
[Debug Guice] Binding creation: 47ms
[Debug Guice] Binding indexing: 0ms
[Debug Guice] Validation: 109ms
[Debug Guice] Static validation: 0ms
[Debug Guice] Static member injection: 0ms
[Debug Guice] Instance injection: 0ms
[Debug Guice] Preloading: 0ms
demo

38. Other Tips
Integrating with the Spring
Framework.
Using JNDI with Guice.
Using JMX.
Guice has built‐in support to inspect an
Injector's bindings at runtime using the
JMX.

39. Summay of Guice
All the DI settings can be
described by Java.
The injection and scope setting are
easy.
Important
Module
Scope
Provider

40. guice‐servlet
What is guice‐servlet?

41. What is guice‐servlet?
guice‐servlet 1.0
Meaning that your servlets and filters
benefit from:
Constructor injection
Type‐safe, idiomatic configuration
Modularization
Guice AOP

42. What is guice‐servlet?
guice‐servlet 1.0
It's very simple, because they are only
6 files.
GuiceFilter
RequestParameters
RequestScoped
ServletModule
ServletScopes
SessionScoped

43. guice‐servlet
Getting Start

44. Getting Start
web.xml
<filter>
<filter‐name>guiceFilter</filter‐name>
<filter‐class>
com.google.inject.servlet.GuiceFilter
</filter‐class>
</filter>
<filter‐mapping>
<filter‐name>guiceFilter</filter‐name>
<url‐pattern>/*</url‐pattern>
</filter‐mapping>

45. Getting Start
Install ServletModule
public class GuiceServletListener
implements ServletContextListener {
protected Injector getInjector() {
return Guice.createInjector(new ServletModule());
}
public void contextInitialize(ServletContext sce) { // setAttribute }
public void contextDestroyed(ServletContextEvent sce) { // removeAttribute }
}
web.xml
<listener>
<listener‐class>example.GuiceServletListener</listener‐class>
</listener>

46. Getting Start
Install ServletModule
public class GuiceServletListener
implements ServletContextListener {
protected Injector getInjector() {
return Guice.createInjector(new ServletModule());
}
public void contextInitialize(ServletContext sce) { // setAttribute }
public void contextDestroyed(ServletContextEvent sce) { // removeAttribute }
}
web.xml
<listener>
<listener‐class>example.GuiceServletListener</listener‐class>
</listener>
see Sample code

47. guice‐servlet
If Java 6 above

48. Guice Tips
Using ServiceLoader
META‐INF/services/com.google.inject.Module
example.ApplicationModule
ApplicationModule.java
public class ApplicationModule extends AbstractModule {
@Override
protected void configure() {
install(new ServletModule());
}
}
ServiceLoader<com.google.inject.Module> module =
ServiceLoader.load(com.google.inject.Module.class);
Injector injector = Guice.createInjector(modules);

49. Guice Tips
Using ServiceLoader
META‐INF/services/com.google.inject.Module
example.ApplicationModule
ApplicationModule.java
public class ApplicationModule extends AbstractModule {
@Override
protected void configure() {
install(new ServletModule());
}
}
ServiceLoader<com.google.inject.Module> module =
ServiceLoader.load(com.google.inject.Module.class);
Injector injector = Guice.createInjector(modules);
demo

50. guice‐servlet
Feature of guice‐servlet

51. guice‐servlet
Annotation
@RequestParameters
@Inject
@RequestParameters
private Map<String, String[]> parameters;
@RequestScoped
@RequestScoped
public class SampleAction {
}
@SessionScoped
@SessionScoped
public class SampleInfo {
}
demo

52. guice‐servlet
Session,Request,Response
Use @Inject
@Inject
private HttpSession session;
@Inject
private ServletRequest request;
@Inject
private ServletResponse response;

53. guice‐servlet
Session,Request,Response
Use @Inject
@Inject
private HttpSession session;
easy! :)
@Inject
private ServletRequest request;
@Inject
private ServletResponse response;

54. guice‐servlet
Session,Request,Response
Use Injector
@Inject private Injector injector;
HttpSession session = injector.getInstance(HttpSession.class);
ServletRequest request = injector.getInstance(ServletRequest.class);
HttpServletRequest request2 =
injector.getInstance(HttpServletRequest.class);
ServletResponse response =
injector.getInstance(ServletResponse.class);
HttpServletResponse response2 =
injector.getInstance(HttpServletResponse.class);

55. guice‐servlet
Session,Request,Response
Use Injector
@Inject private Injector injector;
HttpSession session = injector.getInstance(HttpSession.class);
ServletRequest request = injector.getInstance(ServletRequest.class);
HttpServletRequest request2 =
injector.getInstance(HttpServletRequest.class);
ServletResponse response =
injector.getInstance(ServletResponse.class);
HttpServletResponse response2 =
injector.getInstance(HttpServletResponse.class);
demo

56. with Google App Engine
Using Guice
with Google App Engine

57. with Google App Engine
Guice 1.0 is not supported :(
GAE support was added in rev#937.
http://code.google.com/p/google‐guice/source/detail?r=937
It requires Guice 2 (with or
without AOP), plus the guice‐
servlet extension.

58. with GAE setup
Servlet and Filter Registration
class MyServletModule extends com.google.inject.servlet.ServletModule {
@Override
protected void configureServlets() {
serve(“/*”).with(MyServlet.class);
}
}
Injector Creation
public class MyGuiceServletContextListener
extends com.google.inject.servlet.GuiceServletContextListener {
@Override protected Injector getInjector() {
return Guice.createInjector(new MyServletModule());
}
}

59. with GAE setup
web.xml configration
<filter>
<filter‐name>guiceFilter</filter‐name>
<filter‐class>com.google.inject.servlet.GuiceFilter</filter‐class>
</filter>
<filter‐mapping>
<filter‐name>guiceFilter</filter‐name>
<url‐pattern>/*</url‐pattern>
</filter‐mapping>
<listener>
<listener‐class>
example.MyGuiceServletContextListener
</listener‐class>
</listener>

60. with Google App Engine
Enjoy! Guice
with Google App Engine

61. Haiku
Guice is
not juice
It’s Guice❤

62. Thank you!
:)