多线程编程-线程间通信.管道（五）

布满荆棘的人生 2022-06-01 02:07 238阅读 0赞

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。