使用 Guice DI 实施策略模式

Question

我是

Guice DI

的新人。我正在尝试使用

Strategy

实现

Guice

模式。但我对如何通过Context在

Guice DI

类中注入不同类型的

策略实现

感到困惑。有哪位专家可以帮我解决这个问题吗？以下是我到目前为止的代码。

策略模式

public interface MetricCollectorStrategy {
    List<String> collect(final Context context);
}

public class AMetricCollector implements MetricCollectorStrategy {
 @Override
 public List<String> collect(final Context context) {
    List<String> aMetricList = construct A metric list by some business logic....
    return aMetricList;
 }
}


public class BMetricCollector implements MetricCollectorStrategy {
 @Override
 public List<String> collect(final Context context) {
    List<String> bMetricList = construct B metric list by some business logic....
    return bMetricList;
 }
}


@AllArgsConstructor(onConstructor_ = @Inject)
public class MetricPublisher {

    // This has a method to publish metric
    private final MetricsHelper metricsHelper;
    private final MetricCollectorStrategy metricCollectorStrategy;

 
    public void collectAndPublishMetric(Context context) {
        metricsHelper.emitCollectedCountMetricList(metricCollectorStrategy.collect(context));
    }
}

到那时就可以了。但是如何在客户端创建并注入这两种类型的

MetricCollector

：

@AllArgsConstructor(onConstructor_ = @Inject)
public class Client{
    
  // Some dummy code to simulate the current code
  private final ExistingDependency_1 existingDependency_1;

  private final ExistingDependency_2 existingDependency_2;

  private final ExistingDependency_3 existingDependency_2;


  // Now how to create the metricCollectors here

  AMetricCollector aMetricCollector;
  BMetricCollector bMetricCollector;

  public void someMethod(Context context){


      if(condition){
        aMetricCollector.collectAndPublishMetric(context);
      }else{
        bMetricCollector.collectAndPublishMetric(context);
      }
  }

}

Answer 1

注意你说的地方

// Now how to create the metricCollectors here

不是您实际应该创建 metricCollectors 的地方。这就是依赖注入的要点，您注入依赖项而不是构建它们。

您应该有一个构造函数来接收这些依赖项，并且您的 DI 框架应该创建它们。