FooImpl) cannot be directly injected unless
it is also explicitly bound (bind(FooImpl.class)).
Tools can still retrieve bindings for implicit bindings (bindings created through a linked binding) if explicit bindings are required, however {@link Binding#getProvider} will fail.
By default, explicit bindings are not required.
If a parent injector requires explicit bindings, then all child injectors (and private modules within that injector) also require explicit bindings. If a parent does not require explicit bindings, a child injector or private module may optionally declare itself as requiring explicit bindings. If it does, the behavior is limited only to that child or any grandchildren. No siblings of the child will require explicit bindings.
In the absence of an explicit binding for the target, linked bindings in child injectors create a binding for the target in the parent. Since this behavior can be surprising, it causes an error instead if explicit bindings are required. To avoid this error, add an explicit binding for the target, either in the child or the parent. @since 3.0]]>
{@literal @}Named("foo") Foo.
@since 4.0]]>
bind(ServiceImpl.class);
This statement does essentially nothing; it "binds the {@code ServiceImpl}
class to itself" and does not change Guice's default behavior. You may still
want to use this if you prefer your {@link Module} class to serve as an
explicit manifest for the services it provides. Also, in rare cases,
Guice may be unable to validate a binding at injector creation time unless it
is given explicitly.
bind(Service.class).to(ServiceImpl.class);
Specifies that a request for a {@code Service} instance with no binding
annotations should be treated as if it were a request for a
{@code ServiceImpl} instance. This overrides the function of any
{@link ImplementedBy @ImplementedBy} or {@link ProvidedBy @ProvidedBy}
annotations found on {@code Service}, since Guice will have already
"moved on" to {@code ServiceImpl} before it reaches the point when it starts
looking for these annotations.
bind(Service.class).toProvider(ServiceProvider.class);
In this example, {@code ServiceProvider} must extend or implement
{@code ProviderThe {@link Provider} you use here does not have to be a "factory"; that is, a provider which always creates each instance it provides. However, this is generally a good practice to follow. You can then use Guice's concept of {@link Scope scopes} to guide when creation should happen -- "letting Guice work for you".
bind(Service.class).annotatedWith(Red.class).to(ServiceImpl.class);
Like the previous example, but only applies to injection requests that use
the binding annotation {@code @Red}. If your module also includes bindings
for particular values of the {@code @Red} annotation (see below),
then this binding will serve as a "catch-all" for any values of {@code @Red}
that have no exact match in the bindings.
bind(ServiceImpl.class).in(Singleton.class);
// or, alternatively
bind(ServiceImpl.class).in(Scopes.SINGLETON);
Either of these statements places the {@code ServiceImpl} class into
singleton scope. Guice will create only one instance of {@code ServiceImpl}
and will reuse it for all injection requests of this type. Note that it is
still possible to bind another instance of {@code ServiceImpl} if the second
binding is qualified by an annotation as in the previous example. Guice is
not overly concerned with preventing you from creating multiple
instances of your "singletons", only with enabling your application to
share only one instance if that's all you tell Guice you need.
Note: a scope specified in this way overrides any scope that was specified with an annotation on the {@code ServiceImpl} class.
Besides {@link Singleton}/{@link Scopes#SINGLETON}, there are servlet-specific scopes available in {@code com.google.inject.servlet.ServletScopes}, and your Modules can contribute their own custom scopes for use here as well.
bind(new TypeLiteral<PaymentService<CreditCard>>() {})
.to(CreditCardPaymentService.class);
This admittedly odd construct is the way to bind a parameterized type. It
tells Guice how to honor an injection request for an element of type
{@code PaymentService
bind(Service.class).toInstance(new ServiceImpl());
// or, alternatively
bind(Service.class).toInstance(SomeLegacyRegistry.getService());
In this example, your module itself, not Guice, takes responsibility
for obtaining a {@code ServiceImpl} instance, then asks Guice to always use
this single instance to fulfill all {@code Service} injection requests. When
the {@link Injector} is created, it will automatically perform field
and method injection for this instance, but any injectable constructor on
{@code ServiceImpl} is simply ignored. Note that using this approach results
in "eager loading" behavior that you can't control.
bindConstant().annotatedWith(ServerHost.class).to(args[0]);
Sets up a constant binding. Constant injections must always be annotated.
When a constant binding's value is a string, it is eligile for conversion to
all primitive types, to {@link Enum#valueOf(Class, String) all enums}, and to
{@link Class#forName class literals}. Conversions for other types can be
configured using {@link #convertToTypes(Matcher, TypeConverter)
convertToTypes()}.
{@literal @}Color("red") Color red; // A member variable (field)
. . .
red = MyModule.class.getDeclaredField("red").getAnnotation(Color.class);
bind(Service.class).annotatedWith(red).to(RedService.class);
If your binding annotation has parameters you can apply different bindings to
different specific values of your annotation. Getting your hands on the
right instance of the annotation is a bit of a pain -- one approach, shown
above, is to apply a prototype annotation to a field in your module class, so
that you can read this annotation instance and give it to Guice.
bind(Service.class)
.annotatedWith(Names.named("blue"))
.to(BlueService.class);
Differentiating by names is a common enough use case that we provided a
standard annotation, {@link com.google.inject.name.Named @Named}. Because of
Guice's library support, binding by name is quite easier than in the
arbitrary binding annotation case we just saw. However, remember that these
names will live in a single flat namespace with all the other names used in
your application.
Constructor loneCtor = getLoneCtorFromServiceImplViaReflection();
bind(ServiceImpl.class)
.toConstructor(loneCtor);
In this example, we directly tell Guice which constructor to use in a concrete
class implementation. It means that we do not need to place {@literal @}Inject
on any of the constructors and that Guice treats the provided constructor as though
it were annotated so. It is useful for cases where you cannot modify existing
classes and is a bit simpler than using a {@link Provider}.
The above list of examples is far from exhaustive. If you can think of how the concepts of one example might coexist with the concepts from another, you can most likely weave the two together. If the two concepts make no sense with each other, you most likely won't be able to do it. In a few cases Guice will let something bogus slip by, and will then inform you of the problems at runtime, as soon as you try to create your Injector.
The other methods of Binder such as {@link #bindScope}, {@link #bindInterceptor}, {@link #install}, {@link #requestStaticInjection}, {@link #addError} and {@link #currentStage} are not part of the Binding EDSL; you can learn how to use these in the usual way, from the method documentation. @author crazybob@google.com (Bob Lee) @author jessewilson@google.com (Jesse Wilson) @author kevinb@google.com (Kevin Bourrillion)]]>
bind(Service.class).annotatedWith(Red.class).to(ServiceImpl.class);
bindConstant().annotatedWith(ServerHost.class).to(args[0]);They exist on both modules and on injectors, and their behaviour is different for each:
public class FooApplication {
public static void main(String[] args) {
Injector injector = Guice.createInjector(
new ModuleA(),
new ModuleB(),
. . .
new FooApplicationFlagsModule(args)
);
// Now just bootstrap the application and you're done
FooStarter starter = injector.getInstance(FooStarter.class);
starter.runApplication();
}
}
]]>
The returned map does not include bindings inherited from a {@link #getParent() parent injector}, should one exist. The returned map is guaranteed to iterate (for example, with its {@link Map#entrySet()} iterator) in the order of insertion. In other words, the order in which bindings appear in user Modules.
This method is part of the Guice SPI and is intended for use by tools and extensions.]]>
The returned map does not include bindings inherited from a {@link #getParent() parent injector}, should one exist.
This method is part of the Guice SPI and is intended for use by tools and extensions. @since 3.0]]>
No key may be bound by both an injector and one of its ancestors. This includes just-in-time bindings. The lone exception is the key for {@code Injector.class}, which is bound by each injector to itself. @since 2.0]]>
No key may be bound by both an injector and one of its ancestors. This includes just-in-time bindings. The lone exception is the key for {@code Injector.class}, which is bound by each injector to itself. @since 2.0]]>
An injector can also {@link #injectMembers(Object) inject the dependencies} of already-constructed instances. This can be used to interoperate with objects created by other frameworks or services.
Injectors can be {@link #createChildInjector(Iterable) hierarchical}. Child injectors inherit the configuration of their parent injectors, but the converse does not hold.
The injector's {@link #getBindings() internal bindings} are available for introspection. This enables tools and extensions to operate on an injector reflectively. @author crazybob@google.com (Bob Lee) @author jessewilson@google.com (Jesse Wilson)]]>
Example usage for a binding of type {@code Foo} annotated with {@code @Bar}:
{@code new Key
Example usage for a binding of type {@code Foo} annotated with {@code @Bar}:
{@code new Key
Example usage for a binding of type {@code Foo}:
{@code new Key
{@literal @}Inject
public void setService({@literal @}Transactional Service service) {
...
}
{@code Key} supports generic types via subclassing just like {@link TypeLiteral}.
Keys do not differentiate between primitive types (int, char, etc.) and their corresponding wrapper types (Integer, Character, etc.). Primitive types will be replaced with their wrapper types when keys are created. @author crazybob@google.com (Bob Lee)]]>
In addition to the bindings configured via {@link #configure}, bindings will be created for all methods annotated with {@literal @}{@link Provides}. Use scope and binding annotations on these methods to configure the bindings.]]>
Guice EDSL bindings can be exposed with {@link #expose(Class) expose()}. {@literal @}{@link com.google.inject.Provides Provides} bindings can be exposed with the {@literal @}{@link Exposed} annotation:
public class FooBarBazModule extends PrivateModule {
protected void configure() {
bind(Foo.class).to(RealFoo.class);
expose(Foo.class);
install(new TransactionalBarModule());
expose(Bar.class).annotatedWith(Transactional.class);
bind(SomeImplementationDetail.class);
install(new MoreImplementationDetailsModule());
}
{@literal @}Provides {@literal @}Exposed
public Baz provideBaz() {
return new SuperBaz();
}
}
Private modules are implemented using {@link Injector#createChildInjector(Module[]) parent injectors}. When it can satisfy their dependencies, just-in-time bindings will be created in the root environment. Such bindings are shared among all environments in the tree.
The scope of a binding is constrained to its environment. A singleton bound in a private module will be unique to its environment. But a binding for the same type in a different private module will yield a different instance.
A shared binding that injects the {@code Injector} gets the root injector, which only has access to bindings in the root environment. An explicit binding that injects the {@code Injector} gets access to all bindings in the child environment.
To promote a just-in-time binding to an explicit binding, bind it:
bind(FooImpl.class);@author jessewilson@google.com (Jesse Wilson) @since 2.0]]>
An example of a scope is {@link Scopes#SINGLETON}. @author crazybob@google.com (Bob Lee)]]>
{@code TypeLiteral Along with modeling generic types, this class can resolve type parameters.
For example, to figure out what type {@code keySet()} returns on a {@code
Map {@code
TypeLiteral
@author crazybob@google.com (Bob Lee)
@author jessewilson@google.com (Jesse Wilson)]]>
Obsolete Usage: When used in tandem with {@link FactoryProvider}, constructors annotated with {@code @AssistedInject} trigger a "backwards compatibility mode". The assisted parameters must exactly match one corresponding factory method within the factory interface and all must be in the same order as listed in the factory. In this backwards compatable mode, constructors annotated with AssistedInject are not created by Guice and thus receive none of the benefits.
Constructor parameters must be either supplied by the factory interface and marked with
@Assisted, or they must be injectable.
@author jmourits@google.com (Jerome Mourits)
@author jessewilson@google.com (Jesse Wilson)]]>
public interface PaymentFactory {
Payment create(Date startDate, Money amount);
}
You can name your factory methods whatever you like, such as create, createPayment
or newPayment.
public class RealPayment implements Payment {
{@literal @}Inject
public RealPayment(
CreditService creditService,
AuthService authService,
{@literal @}Assisted Date startDate,
{@literal @}Assisted Money amount) {
...
}
}
public interface PaymentFactory {
Payment create(Date startDate, Money amount);
Payment createWithoutDate(Money amount);
}
public class RealPayment implements Payment {
{@literal @}AssistedInject
public RealPayment(
CreditService creditService,
AuthService authService,
{@literal @}Assisted Date startDate,
{@literal @}Assisted Money amount) {
...
}
{@literal @}AssistedInject
public RealPayment(
CreditService creditService,
AuthService authService,
{@literal @}Assisted Money amount) {
...
}
}
install(new FactoryModuleBuilder()
.implement(Payment.class, RealPayment.class)
.build(PaymentFactory.class));
As a side-effect of this binding, Guice will inject the factory to initialize it for use. The
factory cannot be used until the injector has been initialized.
.implement.
public interface OrderFactory {
Payment create(Date startDate, Money amount);
Shipment create(Customer customer, Item item);
Receipt create(Payment payment, Shipment shipment);
}
[...]
install(new FactoryModuleBuilder()
.implement(Payment.class, RealPayment.class)
// excluding .implement for Shipment means the implementation class
// will be 'Shipment' itself, which is legal if it's not an interface.
.implement(Receipt.class, RealReceipt.class)
.build(OrderFactory.class));
public class PaymentAction {
{@literal @}Inject private PaymentFactory paymentFactory;
public void doPayment(Money amount) {
Payment payment = paymentFactory.create(new Date(), amount);
payment.apply();
}
}
public interface PaymentFactory {
Payment create(
{@literal @}Assisted("startDate") Date startDate,
{@literal @}Assisted("dueDate") Date dueDate,
Money amount);
}
...and to the concrete type's constructor parameters:
public class RealPayment implements Payment {
{@literal @}Inject
public RealPayment(
CreditService creditService,
AuthService authService,
{@literal @}Assisted("startDate") Date startDate,
{@literal @}Assisted("dueDate") Date dueDate,
{@literal @}Assisted Money amount) {
...
}
}
public interface FruitFactory {
Apple getApple(Color color);
}
...
protected void configure() {
install(new FactoryModuleBuilder().build(FruitFactory.class));
}
Note that any type returned by the factory in this manner needs to be an implementation class.
To return two different implementations for the same interface from your factory, use binding
annotations on your return types:
interface CarFactory {
{@literal @}Named("fast") Car getFastCar(Color color);
{@literal @}Named("clean") Car getCleanCar(Color color);
}
...
protected void configure() {
install(new FactoryModuleBuilder()
.implement(Car.class, Names.named("fast"), Porsche.class)
.implement(Car.class, Names.named("clean"), Prius.class)
.build(CarFactory.class));
}
Provides a factory that combines the caller's arguments with injector-supplied values to construct objects.
public interface PaymentFactory {
Payment create(Date startDate, Money amount);
}
You can name your factory methods whatever you like, such as create, createPayment
or newPayment.
public class RealPayment implements Payment {
{@literal @}Inject
public RealPayment(
CreditService creditService,
AuthService authService,
{@literal @}Assisted Date startDate,
{@literal @}Assisted Money amount) {
...
}
}
Any parameter that permits a null value should also be annotated {@code @Nullable}.
bind(PaymentFactory.class).toProvider(
FactoryProvider.newFactory(PaymentFactory.class, RealPayment.class));
As a side-effect of this binding, Guice will inject the factory to initialize it for use. The
factory cannot be used until the injector has been initialized.
public class PaymentAction {
{@literal @}Inject private PaymentFactory paymentFactory;
public void doPayment(Money amount) {
Payment payment = paymentFactory.create(new Date(), amount);
payment.apply();
}
}
public interface PaymentFactory {
Payment create(
{@literal @}Assisted("startDate") Date startDate,
{@literal @}Assisted("dueDate") Date dueDate,
Money amount);
}
...and to the concrete type's constructor parameters:
public class RealPayment implements Payment {
{@literal @}Inject
public RealPayment(
CreditService creditService,
AuthService authService,
{@literal @}Assisted("startDate") Date startDate,
{@literal @}Assisted("dueDate") Date dueDate,
{@literal @}Assisted Money amount) {
...
}
}
Instead of matching factory method arguments to constructor parameters using their names, the parameters are matched by their order. The first factory method argument is used for the first {@literal @}Assisted constructor parameter, etc.. Annotation names have no effect.
Returned values are not created by Guice. These types are not eligible for
method interception. They do receive post-construction member injection.
@param
{@code
Guice.createInjector(...other modules..., DaggerAdapter.from(new SomeDaggerAdapter()));
}
Some notes on usage and compatibility.
In addition to the {@code Map
When multiple modules contribute elements to the map, this configuration
option impacts all of them.
@return this map binder
@since 3.0]]>
Scoping elements independently is supported. Use the {@code in} method to specify a binding scope.]]>
public class SnacksModule extends AbstractModule {
protected void configure() {
MapBinder<String, Snack> mapbinder
= MapBinder.newMapBinder(binder(), String.class, Snack.class);
mapbinder.addBinding("twix").toInstance(new Twix());
mapbinder.addBinding("snickers").toProvider(SnickersProvider.class);
mapbinder.addBinding("skittles").to(Skittles.class);
}
}
With this binding, a {@link Map}{@code In addition to binding {@code Map Contributing mapbindings from different modules is supported. For example,
it is okay to have both {@code CandyModule} and {@code ChipsModule} both
create their own {@code MapBinder The map's iteration order is consistent with the binding order. This is
convenient when multiple elements are contributed by the same module because
that module can order its bindings appropriately. Avoid relying on the
iteration order of elements contributed by different modules, since there is
no equivalent mechanism to order modules.
The map is unmodifiable. Elements can only be added to the map by
configuring the MapBinder. Elements can never be removed from the map.
Values are resolved at map injection time. If a value is bound to a
provider, that provider's get method will be called each time the map is
injected (unless the binding is also scoped, or a map of providers is injected).
Annotations are used to create different maps of the same key/value
type. Each distinct annotation gets its own independent map.
Keys must be distinct. If the same key is bound more than
once, map injection will fail. However, use {@link #permitDuplicates()} in
order to allow duplicate keys; extra bindings to {@code Map Keys must be non-null. {@code addBinding(null)} will
throw an unchecked exception.
Values must be non-null to use map injection. If any
value is null, map injection will fail (although injecting a map of providers
will not).
@author dpb@google.com (David P. Baker)]]>
class SnackMachine {
{@literal @}Inject
public SnackMachine(Map<String, Snack> snacks) { ... }
}
class SnackMachine {
{@literal @}Inject
public SnackMachine(Map<String, Provider<Snack>> snackProviders) { ... }
}
Map<String, Snack>, then this will always return a
TypeLiteral<String>.]]>
Map<String, Snack>, then this will always return a
TypeLiteral<Snack>.]]>
Map<String, Snack>, then this will always return a list of type
List<Map.Entry<String, Binding<Snack>>>.]]>
MapBinderBinding<Map<String, Snack>>
@since 3.0
@author sameb@google.com (Sam Berlin)]]>
{@literal @}MapKey(unwrapValue = true)
{@literal @}Retention(RUNTIME)
public {@literal @}interface MyCustomEnumKey {
MyCustomEnum value();
}
You can also use the whole annotation as the key, if {@code unwrapValue=false}.
When unwrapValue is false, the annotation type will be the key type for the injected map and
the annotation instances will be the key values. If {@code unwrapValue=true}, the value() type
will be the key type for injected map and the value() instances will be the keys values.
@since 4.0]]>
Scoping elements independently is supported. Use the {@code in} method to specify a binding scope.]]>
public class SnacksModule extends AbstractModule {
protected void configure() {
Multibinder<Snack> multibinder
= Multibinder.newSetBinder(binder(), Snack.class);
multibinder.addBinding().toInstance(new Twix());
multibinder.addBinding().toProvider(SnickersProvider.class);
multibinder.addBinding().to(Skittles.class);
}
}
With this binding, a {@link Set}{@code Contributing multibindings from different modules is supported. For
example, it is okay for both {@code CandyModule} and {@code ChipsModule}
to create their own {@code Multibinder The set's iteration order is consistent with the binding order. This is
convenient when multiple elements are contributed by the same module because
that module can order its bindings appropriately. Avoid relying on the
iteration order of elements contributed by different modules, since there is
no equivalent mechanism to order modules.
The set is unmodifiable. Elements can only be added to the set by
configuring the multibinder. Elements can never be removed from the set.
Elements are resolved at set injection time. If an element is bound to a
provider, that provider's get method will be called each time the set is
injected (unless the binding is also scoped).
Annotations are be used to create different sets of the same element
type. Each distinct annotation gets its own independent collection of
elements.
Elements must be distinct. If multiple bound elements
have the same value, set injection will fail.
Elements must be non-null. If any set element is null,
set injection will fail.
@author jessewilson@google.com (Jesse Wilson)]]>
If desired, {@link Collection}{@code
class SnackMachine {
{@literal @}Inject
public SnackMachine(Set<Snack> snacks) { ... }
}
Set<String>, then this will always return a
TypeLiteral<String>.]]>
Set<String>, then this will always return a list of type
List<Binding<String>>.]]>
MultibinderBinding<Set<Boolean>>
@since 3.0
@author sameb@google.com (Sam Berlin)]]>
When an OptionalBinder is added, it will always supply the bindings:
{@code Optional {@code setDefault} is intended for use by frameworks that need a default
value. User code can call {@code setBinding} to override the default.
Warning: Even if setBinding is called, the default binding
will still exist in the object graph. If it is a singleton, it will be
instantiated in {@code Stage.PRODUCTION}.
If setDefault or setBinding are linked to Providers, the Provider may return
{@code null}. If it does, the Optional bindings will be absent. Binding
setBinding to a Provider that returns null will not cause OptionalBinder
to fall back to the setDefault binding.
If neither setDefault nor setBinding are called, it will try to link to a
user-supplied binding of the same type. If no binding exists, the optionals
will be absent. Otherwise, if a user-supplied binding of that type exists,
or if setBinding or setDefault are called, the optionals will return present
if they are bound to a non-null value.
Values are resolved at injection time. If a value is bound to a
provider, that provider's get method will be called each time the optional
is injected (unless the binding is also scoped, or an optional of provider is
injected).
Annotations are used to create different optionals of the same key/value
type. Each distinct annotation gets its own independent binding.
With this module, an {@link Optional}{@code Option 1:
or Option 2:
Default values can be supplied using:
If one module uses setDefault the only way to override the default is to use setBinding.
It is an error for a user to specify the binding without using OptionalBinder if
setDefault or setBinding are called. For example,
public class FrameworkModule extends AbstractModule {
protected void configure() {
OptionalBinder.newOptionalBinder(binder(), Renamer.class);
}
}
public class UserRenamerModule extends AbstractModule {
protected void configure() {
bind(Renamer.class).to(ReplacingRenamer.class);
}
}
With both options, the {@code Optional
public class UserRenamerModule extends AbstractModule {
protected void configure() {
OptionalBinder.newOptionalBinder(binder(), Renamer.class)
.setBinding().to(ReplacingRenamer.class);
}
}
With the above module, code can inject an {@code @LookupUrl String} and it
will supply the DEFAULT_LOOKUP_URL. A user can change this value by binding
public class FrameworkModule extends AbstractModule {
protected void configure() {
OptionalBinder.newOptionalBinder(binder(), Key.get(String.class, LookupUrl.class))
.setDefault().toInstance(DEFAULT_LOOKUP_URL);
}
}
... which will override the default value.
public class UserLookupModule extends AbstractModule {
protected void configure() {
OptionalBinder.newOptionalBinder(binder(), Key.get(String.class, LookupUrl.class))
.setBinding().toInstance(CUSTOM_LOOKUP_URL);
}
}
... would generate an error, because both the framework and the user are trying to bind
{@code @LookupUrl String}.
@author sameb@google.com (Sam Berlin)
@since 4.0]]>
public class FrameworkModule extends AbstractModule {
protected void configure() {
OptionalBinder.newOptionalBinder(binder(), Key.get(String.class, LookupUrl.class))
.setDefault().toInstance(DEFAULT_LOOKUP_URL);
}
}
public class UserLookupModule extends AbstractModule {
protected void configure() {
bind(Key.get(String.class, LookupUrl.class)).toInstance(CUSTOM_LOOKUP_URL);
}
}
Optional<String>, then this will always return a
Binding<String>.]]>
Optional<String>, then this will always return a
Binding<String>.]]>
Because the key is specified as an annotation, only Strings, Classes, enums, primitive types and annotation instances are supported as keys. @author sameb@google.com (Sam Berlin) @since 4.0]]>
Example configuration:
{@code
public class MyModule extends ServletModule {
public void configureServlets() {
filter("/*").through(PersistFilter.class);
serve("/index.html").with(MyHtmlServlet.class);
// Etc.
}
}
}
This filter is thread safe and allows you to create injectors concurrently and deploy multiple guice-persist modules within the same injector, or even multiple injectors with persist modules withing the same JVM or web app.
This filter requires the Guice Servlet extension. @author Dhanji R. Prasanna (dhanji@gmail.com)]]>
If the method throws an exception, the transaction will be rolled back unless you have specifically requested not to in the {@link #ignore()} clause.
Similarly, the set of exceptions that will trigger a rollback can be defined in the {@link #rollbackOn()} clause. By default, only unchecked exceptions trigger a rollback. @author Dhanji R. Prasanna (dhanji@gmail.com)]]>
<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>
This filter must appear before every filter that makes use of Guice injection or servlet
scopes functionality. Typically, you will only register this filter in web.xml and register
any other filters (and servlets) using a {@link ServletModule}.
@author crazybob@google.com (Bob Lee)
@author dhanji@gmail.com (Dhanji R. Prasanna)]]>
Part of the EDSL builder language for configuring servlets and filters with guice-servlet. Think of this as an in-code replacement for web.xml. Filters and servlets are configured here using simple java method calls. Here is a typical example of registering a filter when creating your Guice injector:
Guice.createInjector(..., new ServletModule() {
{@literal @}Override
protected void configureServlets() {
serve("*.html").with(MyServlet.class)
}
}
This registers a servlet (subclass of {@code HttpServlet}) called {@code MyServlet} to service
any web pages ending in {@code .html}. You can also use a path-style syntax to register
servlets:
serve("/my/*").with(MyServlet.class)
Every servlet (or filter) is required to be a singleton. If you cannot annotate the class
directly, you should add a separate {@code bind(..).in(Singleton.class)} rule elsewhere in
your module. Mapping a servlet that is bound under any other scope is an error.
Guice.createInjector(..., new ServletModule() {
{@literal @}Override
protected void configureServlets() {
filter("/*").through(MyFilter.class);
filter("*.css").through(MyCssFilter.class);
filter("*.jpg").through(new MyJpgFilter());
// etc..
serve("*.html").with(MyServlet.class);
serve("/my/*").with(MyServlet.class);
serve("*.jpg").with(new MyServlet());
// etc..
}
}
This will traverse down the list of rules in lexical order. For example, a url
"{@code /my/file.js}" (after it runs through the matching filters) will first
be compared against the servlet mapping:
serve("*.html").with(MyServlet.class);
And failing that, it will descend to the next servlet mapping:
serve("/my/*").with(MyServlet.class);
Since this rule matches, Guice Servlet will dispatch to {@code MyServlet}. These
two mapping rules can also be written in more compact form using varargs syntax:
serve("*.html", "/my/*").with(MyServlet.class);
This way you can map several URI patterns to the same servlet. A similar syntax is
also available for filter mappings.
serveRegex("(.)*ajax(.)*").with(MyAjaxServlet.class)
This will map any URI containing the text "ajax" in it to {@code MyAjaxServlet}. Such as:
Map<String, String> params = new HashMap<String, String>();
params.put("name", "Dhanji");
params.put("site", "google.com");
...
serve("/*").with(MyServlet.class, params)
...
filter("/*").through(Key.get(Filter.class, Fave.class));
Where {@code Filter.class} refers to the Servlet API interface and {@code Fave.class} is a
custom binding annotation. Elsewhere (in one of your own modules) you can bind this
filter's implementation:
bind(Filter.class).annotatedWith(Fave.class).to(MyFilterImpl.class);See {@link com.google.inject.Binder} for more information on binding syntax.
Guice Servlet allows you to register several instances of {@code ServletModule} to your injector. The order in which these modules are installed determines the dispatch order of filters and the precedence order of servlets. For example, if you had two servlet modules, {@code RpcModule} and {@code WebServiceModule} and they each contained a filter that mapped to the same URI pattern, {@code "/*"}:
In {@code RpcModule}:
filter("/*").through(RpcFilter.class);
In {@code WebServiceModule}:
filter("/*").through(WebServiceFilter.class);
Then the order in which these filters are dispatched is determined by the order in which
the modules are installed:
install(new WebServiceModule()); install(new RpcModule());In the case shown above {@code WebServiceFilter} will run first. @since 2.0]]>
The returned callable will throw a {@link ScopingException} when called if the HTTP request scope is still active on the current thread. @param callable code to be executed in another thread, which depends on the request scope. @param seedMap the initial set of scoped instances for Guice to seed the request scope with. To seed a key with null, use {@code null} as the value. @return a callable that will invoke the given callable, making the request context available to it. @throws OutOfScopeException if this method is called from a non-request thread, or if the request has completed. @since 3.0]]>
Because request-scoped objects are not typically thread-safe, the callable returned by this method must not be run on a different thread until the current request scope has terminated. The returned callable will block until the current thread has released the request scope. @param callable code to be executed in another thread, which depends on the request scope. @return a callable that will invoke the given callable, making the request context available to it. @throws OutOfScopeException if this method is called from a non-request thread, or if the request has completed. @since 4.0]]>
The elements of an injector can be inspected and exercised. Use {@link com.google.inject.Injector#getBindings Injector.getBindings()} to reflect on Guice injectors. @author jessewilson@google.com (Jesse Wilson) @author crazybob@google.com (Bob Lee) @since 2.0]]>
1 and 3 are returned.
In the cases where stack trace is not available (i.e., the stack trace was not collected), it returns -1 for all module positions.]]>
The {@link #getStackTrace()} refers to the sequence of calls ends at one of {@link com.google.inject.Binder} {@code bindXXX()} methods and eventually defines the element. Note that {@link #getStackTrace()} lists {@link StackTraceElement StackTraceElements} in reverse chronological order. The first element (index zero) is the last method call and the last element is the first method invocation. By default, the stack trace is not collected. The default behavior can be changed by setting the {@code guice_include_stack_traces} flag value. The value can be either {@code OFF}, {@code ONLY_FOR_DECLARING_SOURCE} or {@code COMPLETE}. Note that collecting stack traces for every binding can cause a performance hit when the injector is created.
The sequence of class names of {@link com.google.inject.Module modules} involved in the element creation can be retrieved by {@link #getModuleClassNames()}. Similar to {@link #getStackTrace()}, the order is reverse chronological. The first module (index 0) is the module that installs the {@link Element element}. The last module is the root module.
In order to support the cases where a Guice {@link Element element} is created from another Guice {@link Element element} (original) (e.g., by {@link Element#applyTo}), it also provides a reference to the original element source ({@link #getOriginalElementSource()}). @since 4.0]]>
Due to issues with generics, the type parameters of this method do not relate to the type of the provider. In practice, the 'B' type will always be a supertype of 'T'.]]>
<V, B> V acceptExtensionVisitor(BindingTargetVisitor<B, V> visitor, ProviderInstanceBinding<? extends B> binding) {
if(visitor instanceof MyCustomExtensionVisitor) {
return ((MyCustomExtensionVisitor<B, V>)visitor).visitCustomExtension(customProperties, binding);
} else {
return visitor.visit(binding);
}
}
'MyCustomExtensionVisitor' in the example above would be an interface the
extension provides that users can implement in order to be notified of custom
extension information. These visitor interfaces must extend from
BindingTargetVisitor.
@since 3.0
@author sameb@google.com (Sam Berlin)]]>
The following rules are followed in determining how fields are bound using this module:
Example use:
public class TestFoo {
// bind(new TypeLiteral{@code >}() {}).toInstance(listOfObjects);
{@literal @}Bind private List{@code
public interface RemoteProvider<T> extends CheckedProvider<T> {
T get() throws CustomExceptionOne, CustomExceptionTwo;
}
When this type is bound using {@link ThrowingProviderBinder}, the value returned or exception thrown by {@link #get} will be scoped. As a consequence, {@link #get} will invoked at most once within each scope. @since 3.0]]>
ThrowingProviderBinder.create(binder())
.bind(RemoteProvider.class, Customer.class)
.providing(CustomerImpl.class);
where CustomerImpl has a constructor annotated with ThrowingInject.
@author sameb@google.com (Sam Berlin)
@since 4.0]]>
public interface RemoteProvider<T> extends ThrowingProvider<T, RemoteException> { }
When this type is bound using {@link ThrowingProviderBinder}, the value returned or exception thrown by {@link #get} will be scoped. As a consequence, {@link #get} will invoked at most once within each scope. @author jmourits@google.com (Jerome Mourits) @author jessewilson@google.com (Jesse Wilson) @deprecated use {@link CheckedProvider} instead.]]>
You can use a fluent API and custom providers:
ThrowingProviderBinder.create(binder())
.bind(RemoteProvider.class, Customer.class)
.to(RemoteCustomerProvider.class)
.in(RequestScope.class);
class MyModule extends AbstractModule {
configure() {
ThrowingProviderBinder.install(this, binder());
}
{@literal @}CheckedProvides(RemoteProvider.class)
{@literal @}RequestScope
Customer provideCustomer(FlakyCustomerCreator creator) throws RemoteException {
return creator.getCustomerOrThrow();
}
}
ThrowingProviderBinder.create(binder())
.bind(RemoteProvider.class, Customer.class)
.providing(CustomerImpl.class)
.in(RequestScope.class);
Prefer to write smaller modules that can be reused and tested without overrides. @param modules the modules whose bindings are open to be overridden]]>
Prefer to write smaller modules that can be reused and tested without overrides. @param modules the modules whose bindings are open to be overridden]]>