java - 用 Dagger 改造类的 HashMap

Question

我对依赖注入(inject)有点陌生，我有疑问。在我的应用程序中，我有一个 HashMap 来存储用于 RetroFit 的构建类(如缓存)，但现在我正在使用 Dagger 转向 DI，我想知道如何实现相同的行为。

我的代码:

private Map<String, Object> restInstances;
public <T> T getRestClient(Class<T> clazz) {
        T client = null;

        if ((client = (T) restInstances.get(clazz.getCanonicalName())) != null) {
            return client;
        }

        client = restAdapter.create(clazz);
        restInstances.put(clazz.getCanonicalName(), client);
        return client;
    }

开始使用 DI 后，我的“模块”类:

 @Provides @Singleton
    public JobManager providesJobManager(){
        Configuration config = new Configuration.Builder(app)
                .minConsumerCount(1).maxConsumerCount(3).loadFactor(3).customLogger(new CustomLogger() {
                    private static final String TAG = "JOBS";

                    @Override
                    public boolean isDebugEnabled() {
                        return true;
                    }

                    @Override
                    public void d(String text, Object... args) {
                        Log.d(TAG, String.format(text, args));
                    }

                    @Override
                    public void e(Throwable t, String text, Object... args) {
                        Log.e(TAG, String.format(text, args));
                    }

                    @Override
                    public void e(String text, Object... args) {
                        Log.e(TAG, String.format(text, args));
                    }
                })
                .consumerKeepAlive(120).build();

        return new JobManager(app, config);
    }

    @Provides @Singleton
    public RestAdapter providesRestAdapter()
    {
        restInstances = new HashMap<String, Object>();
        return new RestAdapter.Builder()
                .setEndpoint("http://192.168.0.23:9000/api")
                .setLogLevel(RestAdapter.LogLevel.FULL).build();
    }

那么，如何将这个“缓存”哈希注入(inject)到我的应用程序中？

谢谢

Answer 1

您可以创建一个类，其唯一目的是提供休息接口(interface)类。这是接口(interface)/实现

public interface RestApiProvider {
    public <T> T getRestClient(Class<T> clazz);
}

public class RestApiProviderImpl implements RestApiProvider {
    private Map<String, Object> restInstances = new HashMap<String, Object>();
    private RestAdapter restAdapter;

    @Inject
    RestApiProvider(RestAdapter restAdapter) {
        this.restAdapter = restAdapter;
    }

    public <T> T getRestClient(Class<T> clazz) {
        T client = null;

        if ((client = (T) restInstances.get(clazz.getCanonicalName())) != null) {
            return client;
        }

        client = restAdapter.create(clazz);
        restInstances.put(clazz.getCanonicalName(), client);
        return client;
    }

}

在你的模块中你会有

@Provides @Singleton
public RestAdapter providesRestAdapter()
{
    return new RestAdapter.Builder()
            .setEndpoint("http://192.168.0.23:9000/api")
            .setLogLevel(RestAdapter.LogLevel.FULL).build();
}

@Provides @Singleton
public RestApiProvider providesRestApiProvider(RestApiProviderImpl impl) {
    return impl;
}

其工作方式是模块中的 RestAdapter Provider 将用作 RestApiProviderImpl 实例中的依赖项。现在，在任何需要获取 RestApi 类实例的地方，您只需注入(inject) RestApiProvider 即可。

@Inject
RestApiProvider restApiProvider;

// Somewhere in your code
RestApiClassOfSomeSort instance = restApiProvider.getRestClient(RestApiClassOfSomeSort.class);
instance.// do what you need!