java - Constructor中如何处理Writer、Result、OutputStream？

Question

我有一个类封装了一个 StAX Writer 用于特殊的业务 XML 编写。您可以插入一些域对象，逻辑会生成足够的 XML。

出于安全原因，我不想提供 XMLStreamWriter 实例，因此此类是唯一负责写入此编写器的类。 XMLStreamWriter 将在此类中实例化。为了支持几乎所有的输出变体，例如 Result、OutputStream 和 Writer，我还为这些变体提供了构造。

public CustomStreamWriter ([...], Result result) {
      this([...], (Object) result);
}

public CustomStreamWriter ([...], OutputStream outputStream) {
      this([...], (Object) outputStream);
}

public CustomStreamWriter ([...], Writer writer) {
      this([...], (Object) writer);
}

protected CustomStreamWriter ([...], Object outputHandler) {
    // Initialize some final fields and do some stuff with [...]
    XMLOutputFactory factory = XMLOutputFactory.newInstance();

    if(outputHandler instanceof OutputStream) {
       this.writer = factory.createXMLStreamWriter((OutputStream) outputHandler);
    } else if(outputHandler instanceof Result) {
       this.writer = factory.createXMLStreamWriter((Result) outputHandler);
    } else if(outputHandler instanceof Writer) {
       this.writer = factory.createXMLStreamWriter((Writer) outputHandler);
    }
}

当我看到它时，我认为这是非常丑陋的，而且不是实现此目标的巧妙方法。 Stackoverflow，你对我有什么提示吗？

Answer 1

我会这样写。

public CustomStreamWriter ([...], Writer writer) throws XMLStreamException {
    this([...], XMLOutputFactory.newInstance().createXMLStreamWriter(writer);
}

protected CustomStreamWriter ([...], XMLStreamWriter outputHandler) {
    this.writer = writer;
}

如果构造函数抛出异常，构造函数无法处理它并创建一个有效的对象，因此抛出异常是一种明智的处理方式。