java多线程编程之管道通信详解

java多线程编程之管道通信详解

上一章节讲了wait/notify通信，这一节我们来探讨使用管道进行通信。

java中提供了IO流使我们很方便的对数据进行操作，pipeStream是一种特殊的流，用于不同线程间直接传送数据。一个线程将数据发送到输出管道，另一个线程从输入管道读取数据。通过管道实现通信不需要借助临时文件这类东西。

java中提供了四个类使得线程间可以通信：

①字节流：PipeInputStream，PipedOutputStream

②字符流：PipedReader，PipedWriter

下面我们看看字节流的实现方法：

package pipeInputOutput;

//输出流

import java.io.IOException;

import java.io.PipedOutputStream;

public class WriteDate {

public void writeMethod(PipedOutputStream out) {

try {

System.out.println("write:");

for(int i=0;i<300;i++) {

String outDate=""+(i+1);

out.write(outDate.getBytes());

System.out.print(outDate);

}

System.out.println();

out.close();

}catch(IOException e) {

e.printStackTrace();

}

}

}

package pipeInputOutput;

//输入流

import java.io.IOException;

import java.io.PipedInputStream;

public class ReadDate {

public void ReadDate(PipedInputStream input) {

try {

System.out.println("read:");

byte[] byteArray=new byte[20];

int readLength=input.read(byteArray);

while(readLength!=-1) {

String newDate=new String(byteArray,0,readLength);

System.out.print(newDate);

readLength=input.read(byteArray);

}

System.out.println();

input.close();

}catch(IOException e){

e.printStackTrace();

}

}

}

package pipeInputOutput;

import java.io.PipedOutputStream;

//输出线程

public class ThreadWrite extends Thread {

private WriteDate write;

private PipedOutputStream out;

public ThreadWrite(WriteDate write,PipedOutputStream out) {

super();

this.write=write;

this.out=out;

}

public void run() {

write.writeMethod(out);

}

}

package pipeInputOutput;

import java.io.PipedInputStream;

//输入线程

public class ThreadRead extends Thread{

private ReadDate read;

private PipedInputStream in;

public ThreadRead(ReadDate read,PipedInputStream in) {

super();

this.read=read;

this.in=in;

}

public void run() {

read.ReadDate(in);

}

}

package pipeInputOutput;

import java.io.IOException;

import java.io.PipedInputStream;

import java.io.PipedOutputStream;

//测试方法

public class Run {

public static void main(String[] args) {

try {

WriteDate write=new WriteDate();

ReadDate read=new ReadDate();

PipedInputStream inputStream=new PipedInputStream();

PipedOutputStream outputStream=new PipedOutputStream();

//输出流与输入流进行连接。

outputStream.connect(inputStream);

//inputStream.connect(outputStream);

ThreadRead readThread=new ThreadRead(read,inputStream);

readThread.start();//先启动输出线程

Thread.sleep(2000);

ThreadWrite writeThread=new ThreadWrite(write,outputStream);

writeThread.start();//后启动输入线程

} catch (IOException e) {

e.printStackTrace();

} catch (InterruptedExcepyFZUMfVtion e) {

e.printStackTrace();

}

}

}

控制台输出：

read:

write:

123456789101112131415161718192021...

123456789101112131415161718192021...

上面测试中，先启动输入线程，然后因为没有线程被写入所以线程被阻塞，知道有数据写入。

我们接着继续看看字符流的实现方法：

package pipeInputOutput1;

import java.io.IOException;

import java.io.PipedWriter;

//字符输出流

public class WriteDate {

public void writeMethod(PipedWriter out) {

try {

System.out.println("write:");

for(int i=0;i<300;i++) {

String outDate=""+(i+1);

out.write(outDate);

System.out.print(outDate);

}

System.out.println();

out.close();

}catch(IOException e) {

e.printStackTrace();

}

}

}

package pipeInputOutput1;

import java.io.IOException;

import java.io.PipedReader;

//字符输入流

public class ReadDate {

public void readMethod(PipedReader in) {

try {

System.out.println("read:");

char[] byteArray=new char[20];

int readLength=in.read(byteArray);

while(readLength!=-1) {

String newDate=new String(byteArray,0,readLength);

System.out.print(newDate);

readLength=in.read(byteArray);

}

System.out.println();

in.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

package pipeInputOutput1;

import java.io.PipedWriter;

//输出流线程

public class WriteThread extends Thread {

private WriteDate write;

private PipedWriter out;

public WriteThread(WriteDate write,PipedWriter out) {

super();

this.write=write;

this.out=out;

}

public void run() {

write.writeMethod(out);

}

}

package pipeInputOutput1;

import java.io.PipedReader;

//输入流线程

public class ReadThread extends Thread{

private ReadDate read;

private PipedReader in;

public ReadThread(ReadDate read,PipedReader in) {

super();

this.read=read;

this.in=in;

}

public void run() {

read.readMethod(in);

}

}

package pipeInputOutput1;

import java.io.IOException;

import java.io.PipedReader;

import java.io.PipedWriter;

//测试方法

public class run {

public static void main(String[] args) {

try {

WriteDate write=new WriteDate();

ReadDate read=new ReadDate();

PipedWriter out=new PipedWriter();

PipedReader in=new PipedReader();

//连接输出流与输入流

out.connect(in);

//in.connect(out);

ReadThread threadread=new ReadThread(read,in);

threadread.start();

Thread.sleep(2000);

WriteThread threadwrite=new WriteThread(write,out);

threadwrite.start();

} catch (IOException e) {

e.printStackTrace();

} catch (InterruptedException e) {

e.printStackTrace();

}

}

}

字符流额字节流大同小异，上面的例子中字符流不需要创建字节数组而已。

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