如何使用Guice`Module`注入構造函數接受Class的地方？

Question

標題描述了我的問題。

E.g.

public class EntryDAOModule extends AbstractModule { 

    @Override 
    protected void configure() { 
     bind(EntryDAO.class).to(EntryDTOMongoImpl.class); // what should this be?  
    } 
} 

如圖所示，應該是什麼參數.to，給出以下：

public class GenericDAOMongoImpl<T, K extends Serializable> extends BasicDAO<T, K> { 
    public GenericDAOMongoImpl(Class<T> entityClass) throws UnknownHostException { 
     super(entityClass, ConnectionManager.getDataStore()); 
    } 
} 

public class EntryDAOMongoImpl extends GenericDAOMongoImpl<EntryDTOMongoImpl, ObjectId> implements EntryDAO<EntryDTOMongoImpl> { 
    private static final Logger logger = Logger.getLogger(EntryDAOMongoImpl.class); 

    @Inject 
    public EntryDAOMongoImpl(Class<EntryDTOMongoImpl> entityClass) throws UnknownHostException { 
     super(entityClass); 
    } 
    ... 
} 

我如何實例化EntryDAOMongoImpl類，像這樣：

Injector injector = Guice.createInjector(new EntryDAOModule()); 
this.entryDAO = injector.getInstance(EntryDAO.class); // what should this be? 

Answer 1

什麼你會在這裏需要創建一個工廠。使用輔助注射可以幫助你。

你可以看到我的previous post regarding assisted injection

但這裏是你的情況下精確解：

EntryDAOMongoImpl：

public class EntryDAOMongoImpl extends GenericDAOMongoImpl<EntryDTOMongoImpl, ObjectId> implements EntryDAO<EntryDTOMongoImpl> { 
    private static final Logger logger = Logger.getLogger(EntryDAOMongoImpl.class); 

    @Inject 
    public EntryDAOMongoImpl(@Assisted Class<EntryDTOMongoImpl> entityClass) throws UnknownHostException { 
     super(entityClass); 
    } 
    ... 
} 

廠：

public interface EntryDAOFactory { 
    public EntryDAOMongoImpl buildEntryDAO(Class<EntryDTOMongoImpl> entityClass); 
} 

模塊：

public class EntryDAOModule extends AbstractModule { 

    @Override 
    protected void configure() { 
     //bind(EntryDAO.class).to(EntryDAOMongoImpl.class); // what should this be? 

     FactoryModuleBuilder factoryModuleBuilder = new FactoryModuleBuilder(); 
     install(factoryModuleBuilder.build(EntryDAOFactory.class)); 
    } 
} 

用法：

Injector injector = Guice.createInjector(new EntryDAOModule()); 
EntryDAOFactory factory = injector.getInstance(EntryDAOFactory.class); 
this.entryDAO = factory.buildEntryDAO(entityClass); 

如果你將要使用EntryDAOMongoImpl作爲singelton（單身海事組織的自然使用），那麼你可以不用你的模塊內輔助注射執行以下操作：

public class EntryDAOModule extends AbstractModule { 

    @Override 
    protected void configure() { 
     EtnryDTOMongoImpl dto = new EntryDTOMongoImpl(TargetEntry.class); //guessing here 
     bind(EntryDAO.class).toInstance(new EntryDAOMongoImpl(dto)); // singleton 
    } 
} 

讓我知道這是否有助於