Guice注入泛型类型 [英] Guice injecting Generic type

问题描述

我试图用Guice注入泛型。我有知识库< T>，它位于Cursor类中。

  public class Cursor< T> {
 
 @Inject 
受保护的信息库< T>库; 
  

所以当我创建Cursor<用户>，我也希望Guice将我的资源库注入到Repository<用户>。有没有办法做到这一点？

解决方案

您必须使用 TypeLiteral ： p>

  import com.google.inject.AbstractModule; 
 import com.google.inject.TypeLiteral; 
 
 public class MyModule extends AbstractModule {
 
 @Override 
 protected void configure（）{
 bind（new TypeLiteral< Repository< User>>（ ）{}）。（UserRepository.class）; 
 
 
 $ / code> 

要得到一个的实例， Cursor< T> ，一个注射器是必需的：



  import com.google.inject.Guice; 
 import com.google.inject.Injector; 
 import com.google.inject.Key; 
 import com.google.inject.TypeLiteral; 
 
 public class Main {
 
 public static void main（String [] args）{
 Inject injector = Guice.createInjector（new MyModule（））; 
光标<用户> instance = 
 injector.getInstance（Key.get（new TypeLiteral< Cursor< User>>（）{}））; 
 System.err.println（instance.repository）; 
 
 
  

更多详情常见问题。

I'am trying to Inject generic type with Guice. I have Repository< T > which is located in the Cursor class.

public class Cursor<T> {

    @Inject
    protected Repository<T> repository;

So when I create Cursor< User >, I also want the Guice to inject my repository to Repository< User >. Is there a way to do this?

解决方案

You have to use a TypeLiteral:

import com.google.inject.AbstractModule;
import com.google.inject.TypeLiteral;

public class MyModule extends AbstractModule {

  @Override
  protected void configure() {
    bind(new TypeLiteral<Repository<User>>() {}).to(UserRepository.class);
  }
}

To get an instance of Cursor<T>, an Injector is required:

import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;

public class Main {

  public static void main(String[] args) {
    Injector injector = Guice.createInjector(new MyModule());
    Cursor<User> instance = 
        injector.getInstance(Key.get(new TypeLiteral<Cursor<User>>() {}));
    System.err.println(instance.repository);
  }
}

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