多线程编程-线程间通信.管道（五）

最新推荐文章于 2022-08-10 17:21:59 发布

原创最新推荐文章于 2022-08-10 17:21:59 发布 · 725 阅读

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文章标签：

#线程间通信 #管道 #字节流 #字符流

多线程编程专栏收录该内容

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本文介绍如何使用Java中的管道流（Pipe Stream）实现线程间的数据通信。包括字节流（PipedOutputStream 和 PipedInputStream）和字符流（PipedWriter 和 PipedReader）的使用方法，并给出具体的测试代码。

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通过管道进行线程间通信：字节流（PipedOutputStream，PipedInputStream）

在Java中提供了各种各样的输入/输出流Stream，其中管道流（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。使用管道实现线程间的通信，不需要借助类似临时文件之类的东西。

测试代码：

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

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

public class ThreadWrite extends Thread{
	private WriteData wd;
	private PipedOutputStream pos;
	public ThreadWrite(WriteData wd, PipedOutputStream pos) {
		super();
		this.wd = wd;
		this.pos = pos;
	}
	
	@Override
	public void run(){
		wd.writeMethod(pos);
	}
}

public class ThreadRead extends Thread{
	private ReadData rd;
	private PipedInputStream pis;
	public ThreadRead(ReadData rd, PipedInputStream pis) {
		this.rd = rd;
		this.pis = pis;
	}
	
	@Override
	public void run(){
		rd.readMethod(pis);
	}
}

public class RunTest {

	public static void main(String[] args) {
		try{
			WriteData wd = new WriteData();
			ReadData rd = new ReadData();
			PipedInputStream pis = new PipedInputStream();
			PipedOutputStream pos = new PipedOutputStream();
			pos.connect(pis);
			//pis.connect(pos);
			ThreadRead tr = new ThreadRead(rd, pis);
			tr.start();
			Thread.sleep(2000);
			ThreadWrite tw = new ThreadWrite(wd, pos);
			tw.start(); 
		}catch(IOException | InterruptedException e){
			e.printStackTrace();
		}
	}
}

运行结果：

Read :
write :
123456789101112123456789101....

读取线程启动后，由于还没数据写入，所以线程阻塞在read中，直到有数据写入，继续运行。

通过管道进行进程间通信：字符流（PipedWriter，PipedReader）

在管道中也可以传递字符流。

测试代码：

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

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

public class ThreadWrite extends Thread{
	private WriteData wd;
	private PipedWriter pos;
	public ThreadWrite(WriteData wd, PipedWriter pos) {
		super();
		this.wd = wd;
		this.pos = pos;
	}
	
	@Override
	public void run(){
		wd.writeMethod(pos);
	}
}

public class ThreadRead extends Thread{
	private ReadData rd;
	private PipedReader pis;
	public ThreadRead(ReadData rd, PipedReader pis) {
		this.rd = rd;
		this.pis = pis;
	}
	
	@Override
	public void run(){
		rd.readMethod(pis);
	}
}

public class RunTest {

	public static void main(String[] args) {
		try{
			WriteData wd = new WriteData();
			ReadData rd = new ReadData();
			PipedReader pis = new PipedReader();
			PipedWriter pos = new PipedWriter();
			pos.connect(pis);
			//pis.connect(pos);
			ThreadRead tr = new ThreadRead(rd, pis);
			tr.start();
			Thread.sleep(2000);
			ThreadWrite tw = new ThreadWrite(wd, pos);
			tw.start(); 
		}catch(IOException | InterruptedException e){
			e.printStackTrace();
		}
	}
}

运行结果也是一样的，两个线程可以通过管道进行字符数据的传输。