英文:
Passing constructors for outer dependency into Guice implementation
问题
我有一个工作，需要从深层存储中读取数据。我正在使用Guice DI来进行项目开发。
已经编写了一个深层存储，并且作为外部依赖项提供。我在实例化Guice中的客户端方面遇到了困难。
以下是代码示例：
JobModule
public class JobModule extends AbstractModule {
private Config config;
JobModule(Config config) {
this.config = config;
}
@Override
protected void configure() {
bind(Reader.class).to(DeepStoreReader.class);
}
@Provides
@Named("config")
Config provideConfig() {
return this.config;
}
}
Reader 接口
public interface Reader {
List<String> getData(String path);
}
DeepStoreReader
public class DeepStoreReader implements Reader {
private final DeepStoreClient deepStoreClient;
DeepStoreReader(@Named("config") Config config) {
this.deepStoreClient = new DeepStoreClient(config);
}
@Override
public List<String> getData(String path) {
return this.deepStoreClient.getData(path);
}
}
问题是我不想在 DeepStoreReader 构造函数内实例化 DeepStoreClient，因为这会使得测试 DeepStoreReader 变得困难，因为我将无法对 DeepStoreClient 进行模拟。
在这种情况下，实例化客户端的首选方式是什么？DeepStoreClient 不是一个 Guice 模块/实现，而是作为外部已发布的依赖项提供的。
PS：我对依赖注入不太熟悉，正在学习 Guice。
英文:
I have a Job, which should read data from deep storage. I am using Guice DI for my project.
There is a deep store already written and coming as an outer dependencie. I am struggling with instantiating the client in Guice
Here is the code
JobModule
public class JobModule extends AbstractModule {
private Config config;
JobModule(Config config) {
this.config = config;
}
@Override
protected void configure() {
bind(Reader.class).to(DeepStoreReader.class);
}
@Provides
@Named("config")
Config provideConfig() {
return this.config;
}
}
Reader Interface
public interface Reader {
List<String> getData(String path);
}
DeepStoreReader
public class DeepStoreReader implements Reader {
private final DeepStoreClient deepStoreClient;
DeepStoreReader(@Named("config") Config config) {
this.deepStoreClient = new DeepStoreClient(config);
}
@Override
public List<String> getData(String path) {
return this.deepStoreClient.getData(path);
}
}
The issue is I don't want to instantiate DeepStoreClient inside the DeepStoreReader constructor, because it becomes difficult to test DeepStoreReader, since I won't be able to mock DeepStoreClient
What is the preferred way to instantiate a client in such cases? DeepStoreClient is not a Guice module/implementation and is coming as an outer published dependency
PS: I am new to DI and learning Guice
答案1
得分: 1
你想要的是构造函数注入，例如：
@Inject
public DeepStoreReader(DeepStoreClient deepStoreClient) {
this.deepStoreClient = deepStoreClient;
}
Guice 将会负责为你实例化 DeepStoreClient。
编辑：
如果 DeepStoreClient 本身有依赖关系，你也可以注解那个构造函数：
@Inject
public DeepStoreClient(@Named("config") Config config) {
// ... 8< ...
}
英文:
What you want is constructor injection, e.g.:
@Inject
public DeepStoreReader(DeepStoreClient deepStoreClient) {
this.deepStoreClient = deepStoreClient;
}
Guice will take care of instantiating the DeepStoreClient for you.
EDIT:
If DeepStoreClient itself has dependencies, you can also annotate that constructor:
@Inject
public DeepStoreClient(@Named("config") Config config) {
// ... 8< ...
}
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