使用方法

PipedReader和PipedWriter即管道输入流和输出流，可用于线程间管道通信。它们和PipedInputStream/PipedOutputStream区别是前者操作的是字符后者是字节。

方法介绍

PipedReader提供的API如下：

//构造方法
PipedReader(PipedWriter src)    //使用默认的buf的大小和传入的pw构造pr
PipedReader(PipedWriter src, int pipeSize)      //使用指定的buf的大小和传入的pw构造pr
PipedReader()       //使用默认大小构造pr
PipedReader(int pipeSize)       //使用指定大小构造pr

//关闭流
void close()
//绑定Writer
void connect(PipedWriter src)
//是否可读
synchronized boolean ready()
//读取一个字符
synchronized int read()
//读取多个字符到cbuf
synchronized int read(char cbuf[], int off, int len)
//Writer调用, 向Reader缓冲区写数据
synchronized void receive(int c)
synchronized void receive(char c[], int off, int len)
synchronized void receivedLast()

PipedWriter提供的API如下：

//构造方法
PipedWriter(PipedReader snk)
PipedWriter()

//绑定Reader Writer
synchronized void connect(PipedReader snk)
//关闭流
void close()
//刷新流,唤醒Reader
synchronized void flush()
//写入1个字符,实际是写到绑定Reader的缓冲区
void write(int c)
//写入多个字符到Reader缓冲区
void write(char cbuf[], int off, int len)

使用示例

/**
 * 写线程
 */
public class Producer extends Thread {
    //输出流
    private PipedWriter writer = new PipedWriter();
    public Producer(PipedWriter writer) {
        this.writer = writer;
    }

    @Override
    public void run() {
        try {
            StringBuilder sb = new StringBuilder();
            sb.append("Hello World!");
            writer.write(sb.toString());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

/**
 * 读取线程
 */
public class Consumer extends Thread{
    //输入流
    private PipedReader reader = new PipedReader();

    public Consumer(PipedReader reader) {
        this.reader = reader;
    }

    @Override
    public void run() {
        try {
            char [] cbuf = new char[20];
            reader.read(cbuf, 0, cbuf.length);
            System.out.println("管道流中的数据为: " + new String(cbuf));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

@org.junit.Test
public void testPipedReaderWriter() {
    /**
     * 管道流通信核心是,Writer和Reader公用一块缓冲区,缓冲区在Reader中申请,
     * 由Writer调用和它绑定的Reader的Receive方法进行写.
     *
     * 线程间通过管道流通信的步骤为
     * 1 建立输入输出流
     * 2 绑定输入输出流
     * 3 Writer写
     * 4 Reader读
     */
    PipedReader reader = new PipedReader();
    PipedWriter writer = new PipedWriter();
    Producer producer = new Producer(writer);
    Consumer consumer = new Consumer(reader);

    try {
        writer.connect(reader);
        producer.start();
        consumer.start();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

运行结果如下：管道流中的数据为: Hello World!