java - Java 中 InputStream 的多个读取器

Question

我有一个 InputStream，我正在从中读取字符。我希望多个读者访问此 InputStream。似乎实现此目的的合理方法是将传入数据写入 StringBuffer 或 StringBuilder，并让多个读取器读取它。不幸的是，StringBufferInputStream 已被弃用。 StringReader 读取字符串，而不是不断更新的可变对象。我有哪些选择？自己写？

Answer 1

注意: My other answer更通用(在我看来更好)。

如 @dimo414 所述，下面的答案要求第一位读者始终领先于第二位读者。如果您确实是这种情况，那么这个答案可能仍然更可取，因为它建立在标准类之上。

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要创建两个独立读取同一源的读取器，您必须确保它们不使用同一流中的数据。

这可以通过组合 TeeInputStream 来实现来自 Apache Commons 和 PipedInputStream和 PipedOutputStream如下:

import java.io.*;
import org.apache.commons.io.input.TeeInputStream;
class Test {
    public static void main(String[] args) throws IOException {

        // Create the source input stream.
        InputStream is = new FileInputStream("filename.txt");

        // Create a piped input stream for one of the readers.
        PipedInputStream in = new PipedInputStream();

        // Create a tee-splitter for the other reader.
        TeeInputStream tee = new TeeInputStream(is, new PipedOutputStream(in));

        // Create the two buffered readers.
        BufferedReader br1 = new BufferedReader(new InputStreamReader(tee));
        BufferedReader br2 = new BufferedReader(new InputStreamReader(in));

        // Do some interleaved reads from them.
        System.out.println("One line from br1:");
        System.out.println(br1.readLine());
        System.out.println();

        System.out.println("Two lines from br2:");
        System.out.println(br2.readLine());
        System.out.println(br2.readLine());
        System.out.println();

        System.out.println("One line from br1:");
        System.out.println(br1.readLine());
        System.out.println();
    }
}

输出:

One line from br1:
Line1: Lorem ipsum dolor sit amet,      <-- reading from start

Two lines from br2:
Line1: Lorem ipsum dolor sit amet,      <-- reading from start
Line2: consectetur adipisicing elit,

One line from br1:
Line2: consectetur adipisicing elit,    <-- resumes on line 2