通过管道进行线程间通信

1 述

• 管道流（pipeStream）是一种特殊的流，用于在不同线程间直接传送数据。
• 一个线程发送数据到输出管道，另一个线程从输入管道中读数据。通过使用管道，实现不同线程间的通信，而无须借助于类似临时文件之类的东西。
• 在Java的JDK中提供了4个类来使线程间可以进行通信：
  1）PipedInputStream和PipedOutputStream
  2）PipedReader和PipedWriter

2 使用字节流

使用代码inputStream.connect（outputStream）或outputStream.connect（inputStream）的作用使两个Stream之间产生通信链接，这样才可以将数据进行输出与输入。

package test;
import java.io.IOException;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import service.ReadData;
import service.WriteData;
import extthread.ThreadRead;
import extthread.ThreadWrite;
public class Run {
    public static void main(String[] args) {
        try {
            WriteData writeData = new WriteData();
            ReadData readData = new 
ReadData();
            PipedInputStream inputStream = new PipedInputStream();
            PipedOutputStream outputStream = new PipedOutputStream();
            // inputStream.connect(outputStream);
            outputStream.connect(inputStream);
            ThreadRead threadRead = new ThreadRead(readData, inputStream);
            threadRead.start();
            Thread.sleep(2000);
            ThreadWrite threadWrite = new ThreadWrite(writeData, outputStream);
            threadWrite.start();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

package service;
import java.io.IOException;
import java.io.PipedOutputStream;
public class WriteData {
    public void writeMethod(PipedOutputStream out) {
        try {
            System.out.println("write :");
            for (int i = 0; i < 300; i++) {
                String outData = "" + (i + 1);
                out.write(outData.getBytes());
                System.out.print(outData);
            }
            System.out.println();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

package service;
import java.io.IOException;
import java.io.PipedInputStream;
public class ReadData {
    public void readMethod(PipedInputStream input) {
        try {
            System.out.println("read  :");
            byte[] byteArray = new byte[20];
            int readLength = input.read(byteArray);
            while (readLength != -1) {
                String newData = new String(byteArray, 0, readLength);
                System.out.print(newData);
                readLength = input.read(byteArray);
            }
            System.out.println();
            input.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

3 使用字符流

package service;
import java.io.IOException;
import java.io.PipedWriter;
public class WriteData {
    public void writeMethod(PipedWriter out) {
        try {
            System.out.println("write :");
            for (int i = 0; i < 300; i++) {
                String outData = "" + (i + 1);
                out.write(outData);
                System.out.print(outData);
            }
            System.out.println();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

package service;
import java.io.IOException;
import java.io.PipedReader;
public class ReadData {
    public void readMethod(PipedReader input) {
        try {
            System.out.println("read  :");
            char[] byteArray = new char[20];
            int readLength = input.read(byteArray);
            while (readLength != -1) {
                String newData = new String(byteArray, 0, readLength);
                System.out.print(newData);
                readLength = input.read(byteArray);
            }
            System.out.println();
            input.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

package test;
import java.io.IOException;
import java.io.PipedReader;
import java.io.PipedWriter;
import service.ReadData;
import service.WriteData;
import extthread.ThreadRead;
import extthread.ThreadWrite;
public class Run {
    public static void main(String[] args) {
        try {
            WriteData writeData = new WriteData();
            ReadData readData = new ReadData();
            PipedReader inputStream = new PipedReader();
            PipedWriter outputStream = new PipedWriter();
            // inputStream.connect(outputStream);
            outputStream.connect(inputStream);
            ThreadRead threadRead = new ThreadRead(readData, inputStream);
            threadRead.start();
            Thread.sleep(2000);
            ThreadWrite threadWrite = new ThreadWrite(writeData, outputStream);
            threadWrite.start();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}