java - 单一职责原则重构

Question

我想重构一些代码，使其不违反单一职责原则 (SRP)。

据我了解，以下类可能会因多种原因而发生更改:

• 分析的业务规则可能会发生变化
• 元数据架构可能会发生变化
• 上传方法可能会改变

但是，我很难弄清楚如何将其重构为单独的类。

引擎.java

package com.example;

import java.util.List;

public interface Engine {
  public List<Recording> analyze(List<String> files);
  public List<Recording> getMetadata(List<Recording> recordings);
  public List<Recording> upload(List<Recording> recordings);
}

CallEngine.java

package com.example;

import java.util.ArrayList;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class CallEngine implements Engine {

  final static Logger log = LoggerFactory.getLogger(Main.class);

  public List<Recording> analyze(List<String> files) {
    log.info("Analyzing recording files per business rules...");

    List<Recording> recordings = new ArrayList<Recording>();
    return recordings;
  }

  public List<Recording> getMetadata(List<Recording> r) {
    log.info("Retrieving metadata for calls...");
    List<Recording> recordings = new ArrayList<Recording>();
    return recordings;
  }

  public List<Recording> upload(List<Recording> r) {
    log.info("Uploading calls...");
    List<Recording> recordings = new ArrayList<Recording>();
    return recordings;
  }
}

Answer 1

SRP 主要是通过抽象接口(interface)后面的代码并将不相关功能的责任委托(delegate)给运行时恰好位于接口(interface)后面的任何实现来实现的。

在这种情况下，您需要将职责抽象到自己的接口(interface)后面。

例如...

public interface Analyzer {
    public List<Recording> analyze(List<String> files);
}
public interface Retriever {
    public List<Recording> getMetadata(List<Recording> recordings);
}
public interface Uploader {
    public List<Recording> upload(List<Recording> r);
}

并将它们作为 Engine 实现的可注入(inject)依赖项。

public class CallEngine implements Engine {
    private Analyzer analyzer;
    private Retriever retriever;
    private Uploader uploader;

    public CallEngine(Analyzer analyzer, Retriever retriever, Uploader uploader) {
        this.analyzer = analyzer;
        this.retriever = retriever;
        this.uploader = uploader;        
    }

    public List<Recording> analyze(List<String> files) {
        return analyzer.analyze(files);
    }

    public List<Recording> getMetadata(List<Recording> r) {
        return retriever.getMetadata(r);
    }

    public List<Recording> upload(List<Recording> r) {
        return uploader.upload(r);
    }
}

可以更改它们的运行时实现，而不会影响依赖类实现的总体责任，这使其更能适应更改。