为什么Guava InputSupplier/OutputSupplier不扩展供应商界面？

Question

我的用例是能够在不创建文件的情况下创建FileOutputStream.所以我创建了这个基于Guava的OutputStream:

public class LazyInitOutputStream extends OutputStream {

  private final Supplier<OutputStream> lazyInitOutputStreamSupplier;

  public LazyInitOutputStream(Supplier<OutputStream> outputStreamSupplier) {
    this.lazyInitOutputStreamSupplier = Suppliers.memoize(outputStreamSupplier);
  }

  @Override
  public void write(int b) throws IOException {
    lazyInitOutputStreamSupplier.get().write(b);
  }

  @Override
  public void write(byte b[]) throws IOException {
    lazyInitOutputStreamSupplier.get().write(b);
  }

  @Override
  public void write(byte b[], int off, int len) throws IOException {
    lazyInitOutputStreamSupplier.get().write(b,off,len);
  }


  public static LazyInitOutputStream lazyFileOutputStream(final File file) {
    return lazyFileOutputStream(file,false);
  }

  public static LazyInitOutputStream lazyFileOutputStream(final File file,final boolean append) {
    return new LazyInitOutputStream(new Supplier<OutputStream>() {
      @Override
      public OutputStream get() {
        try {
          return new FileOutputStream(file,append);
        } catch (FileNotFoundException e) {
          throw Throwables.propagate(e);
        }
      }
    });
  }

}

这工作正常,但我看到有InputSupplier/OutputSupplier我可以使用的接口...除了他们不扩展供应商所以我不能使用这里需要的记忆功能,因为我不希望它OutputSupplier像一个工厂.

另外还有Filesapi:

public static OutputSupplier<FileOutputStream> newOutputStreamSupplier(File file,
                                                       boolean append)

有没有办法可以使用OutputSupplier,它会比我现在的代码更优雅？

OutputSupplier没有实现供应商的原因吗？

Answer 1

InputSupplier可以抛出IOException,Supplier但不能.