如何在另一个FilterInputStream中使用FilterInputStream的自定义方法

Question

我有两个扩展FilterInputStream类的流。A从流中读取双精度，B取这些双精度并对它们施加随机噪声。问题是关于如何正确实现第二个流，这样B就可以访问A返回双精度的自定义函数。链接方式如下:

源-> ->双-> B——>双打与噪声

向Turakar致以最诚挚的问候

Answer 1

A FilteredInputStream似乎不太适合您的问题，因为InputStream表示字节序列，但您需要的是double数字序列。一种可能的替代方法是实现Iterator接口。因此，A将变成:

import java.io.InputStream;
import java.util.Iterator;
import java.util.Scanner;
public class DoubleIterator implements Iterator<Double> {
    private Scanner scanner;
    public DoubleIterator(InputStream is) {
        scanner = new Scanner(is);
    }
    @Override
    public boolean hasNext() {
        return scanner.hasNextDouble();
    }
    @Override
    public Double next() {
        return scanner.nextDouble();
    }
    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }
}

而B会变成

import java.util.Iterator;
import java.util.Random;
public class NoiseIterator implements Iterator<Double> {
    Random r = new Random();
    private Iterator<Double> source;
    public NoiseIterator(Iterator<Double> source) {
        this.source = source;
    }
    @Override
    public boolean hasNext() {
        return source.hasNext();
    }
    @Override
    public Double next() {
        return source.next()+r.nextGaussian();
    }
    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }
}

这些类可以按以下方式使用:

String s = "1 56 123 30 0";
Iterator<Double> it = new DoubleIterator(new ByteArrayInputStream(s.getBytes()));
while(it.hasNext()) {
    System.out.println(it.next());
}
it = new NoiseIterator(new DoubleIterator(new ByteArrayInputStream(s.getBytes())));
while(it.hasNext()) {
    System.out.println(it.next());
}

典型输出:

1.0
56.0
123.0
30.0
0.0
-0.011797617285828732
55.71721599815757
123.33995522117877
29.16152453760448
-0.9614750776766922