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 (interruptedexception 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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。