java - Guice/Morphia，辅助注入(inject)错误

Question

(或者可能用法不正确？我是 Guice 的新手) 我收到以下错误:

• 字符串不能用作键；尚未完全指定。

• java.lang.Class T 不能用作键；尚未完全指定。

我有以下内容:

public interface BaseRepository<T, PK> (){
    public void f1();
}

public class BaseRepositoryMongoImpl<T, String> extends BaseDAO<T, String> implements BaseRepository<T, String> {
    @Inject
    BaseRepositoryMongoImpl(MongoClient mongoClient, Morphia morphia,
        String dbName, @Assisted Class<T> type) {
        super(type, mongoClient, morphia, (java.lang.String) dbName);
    }

    public void f1(){}
}

工厂接口(interface)和类

public interface BaseRepositoryFactory {
    public BaseRepository create(Class<?> tableClass);
}

public class BaseRepositoryFactoryImpl implements BaseRepositoryFactory {

    private final MongoClientProvider mongoClientProvider;
    private final MorphiaProvider morphiaProvider;

    @Inject
    public BaseRepositoryFactoryImpl(MongoClientProvider mongoClientProvider,
        MorphiaProvider morphiaProvider) {
        this.mongoClientProvider = mongoClientProvider;
        this.morphiaProvider = morphiaProvider;
    }

    @Override
    public BaseRepository create(Class<?> tableClass) {
        return new BaseRepositoryMongoDBImpl(mongoClientProvider.get(),
                morphiaProvider.get(),
                "DATABASE_NAME", //comes from properties
                tableClass);
    }
}

提供者类

public class MongoClientProvider implements Provider<MongoClient> {

    @Override
    public MongoClient get() {
        MongoClient mongoClient = null;
        try {
            //for sake of simplicity, all properties code is removed
            //the database name is part of the properties
            mongoClient = new MongoClient("DATABASE_HOST");
        } catch (UnknownHostException ex) {
            Logger.error("Severe Error: Unknown database host", ex);
        }

        return mongoClient;
    }
}

public class MorphiaProvider implements Provider<Morphia> {
    @Override
    public Morphia get() {
        Morphia morphia = new Morphia();
        //for sake of simplicity, all properties code is removed
        //the package name is part of the properties
        morphia.mapPackage("MODEL_PACKAGE", true); 
        return morphia;
    }
}

最后是模块类

public class DatabaseModule extends AbstractModule {
    @Override
    protected void configure() {
        install(new FactoryModuleBuilder()
                .implement(BaseRepository.class, BaseRepositoryMongoDBImpl.class)
                .build(BaseRepositoryFactory.class));
    }
}

我需要在模块类中使用 TypeLiteral 进行任何操作吗？

另外，我可以将 BaseRepositoryFactory 变量声明为

@Inject
private static BaseRepositoryFactory baseRepo;

提前致谢!

Answer 1

首先:你不能注入(inject)一个普通的字符串，guice只是不知道你想要注入(inject)什么。使用限定符来指定您需要什么。最简单的修饰符:@Named。

所以:

@Inject
@Named("foo")
private String myString;

@Provides
@Named("foo")
public String myString() {
   return ... whatever myString should be ... constant? property? DB value?
}

第二:您的辅助注入(inject)方法不是“guicy”方式。查看assisted inject extension ，您不必自己实现接口(interface):

install(new FactoryModuleBuilder()
 .implement(Payment.class, RealPayment.class)
 .build(PaymentFactory.class));

这样，您就可以删除一些代码，从而使搜索真正的问题变得更加容易。

第三:您可以使用requestStaticInjection() ，但通常你不应该这样做。依赖注入(inject)和静态值持有者的概念不匹配，你会遇到很多麻烦，只需使用单例绑定(bind)即可。