io.druid.guice

Class PolyBind

java.lang.Object

io.druid.guice.PolyBind

public class PolyBind
extends Object

Provides the ability to create "polymorphic" bindings. Where the polymorphism is actually just making a decision based on a value in a Properties. The workflow is that you first create a choice by calling createChoice(). Then you create options using the binder returned by the optionBinder() method. Multiple different modules can call optionBinder and all options will be reflected at injection time as long as equivalent interface Key objects are passed into the various methods.

Constructor Summary

Constructors

Constructor and Description
PolyBind()

Method Summary

Methods

Modifier and Type	Method and Description
static <T> com.google.inject.binder.ScopedBindingBuilder	createChoice(com.google.inject.Binder binder, String property, com.google.inject.Key<T> interfaceKey, com.google.inject.Key<? extends T> defaultKey) Sets up a "choice" for the injector to resolve at injection time.
static <T> com.google.inject.binder.ScopedBindingBuilder	createChoiceWithDefault(com.google.inject.Binder binder, String property, com.google.inject.Key<T> interfaceKey, com.google.inject.Key<? extends T> defaultKey, String defaultPropertyValue) Sets up a "choice" for the injector to resolve at injection time.
static <T> com.google.inject.multibindings.MapBinder<String,T>	optionBinder(com.google.inject.Binder binder, com.google.inject.Key<T> interfaceKey) Binds an option for a specific choice.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PolyBind

public PolyBind()

Method Detail

createChoice

public static <T> com.google.inject.binder.ScopedBindingBuilder createChoice(com.google.inject.Binder binder,
                                                             String property,
                                                             com.google.inject.Key<T> interfaceKey,
                                                             com.google.inject.Key<? extends T> defaultKey)

Sets up a "choice" for the injector to resolve at injection time.

Type Parameters:

T - interface type

Parameters:

binder - the binder for the injector that is being configured

property - the property that will be checked to determine the implementation choice

interfaceKey - the interface that will be injected using this choice

defaultKey - the default instance to be injected if the property doesn't match a choice. Can be null

Returns:

A ScopedBindingBuilder so that scopes can be added to the binding, if required.

createChoiceWithDefault

public static <T> com.google.inject.binder.ScopedBindingBuilder createChoiceWithDefault(com.google.inject.Binder binder,
                                                                        String property,
                                                                        com.google.inject.Key<T> interfaceKey,
                                                                        com.google.inject.Key<? extends T> defaultKey,
                                                                        String defaultPropertyValue)

Sets up a "choice" for the injector to resolve at injection time.

Type Parameters:

T - interface type

Parameters:

binder - the binder for the injector that is being configured

property - the property that will be checked to determine the implementation choice

interfaceKey - the interface that will be injected using this choice

defaultKey - the default instance to be injected if the property doesn't match a choice. Can be null

defaultPropertyValue - the default property value to use if the property is not set.

Returns:

A ScopedBindingBuilder so that scopes can be added to the binding, if required.

optionBinder

public static <T> com.google.inject.multibindings.MapBinder<String,T> optionBinder(com.google.inject.Binder binder,
                                                                   com.google.inject.Key<T> interfaceKey)

Binds an option for a specific choice. The choice must already be registered on the injector for this to work.

Type Parameters:

T - interface type

Parameters:

binder - the binder for the injector that is being configured

interfaceKey - the interface that will have an option added to it. This must equal the Key provided to createChoice

Returns:

A MapBinder that can be used to create the actual option bindings.