java线程间通信之通过管道进行通信

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，而不需要借助临时文件之类的东西。

jdk中提供了四个类来使线程间可以通信：

1）PipedInputStream和PipedOutputStream

2）PipedReader和PipedWriter

先看看字节流的示例：

 public class ReadData {

     public void readMethod(PipedInputStream in) throws IOException{
         System.out.println("begin read...");
         byte[] b = new byte[20];
         int readLength = in.read(b);
         while (readLength != -1) {
             String newData = new String(b, 0, readLength);
             System.out.println("read:"+newData);
             readLength = in.read(b);
         }
         in.close();
         System.out.println("end read...");
     }

 }

 public class WriteData {

     public void writeMethod(PipedOutputStream out) throws IOException{
         System.out.println("begin write...");
         for (int i = 0; i < 10; i++) {
             out.write((""+i).getBytes());
             System.out.println("write:"+i);
         }
         out.close();
         System.out.println("end write...");
     }
 }

 public class ThreadRead extends Thread {

     private ReadData readData;
     private PipedInputStream in;

     public ThreadRead(ReadData readData, PipedInputStream in) {
         this.readData = readData;
         this.in = in;
     }

     @Override
     public void run() {
         try {
             readData.readMethod(in);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
 }

 public class ThreadWrite extends Thread {

     private WriteData writeData;
     private PipedOutputStream out;

     public ThreadWrite(WriteData writeData, PipedOutputStream out) {
         this.writeData = writeData;
         this.out = out;
     }

     @Override
     public void run() {
         try {
             writeData.writeMethod(out);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
 }

 public class Run {
     public static void main(String[] args) throws IOException, InterruptedException {
         WriteData writeData = new WriteData();
         ReadData readData = new ReadData();

         PipedOutputStream out = new PipedOutputStream();
         PipedInputStream in = new PipedInputStream();

         in.connect(out);

         new ThreadWrite(writeData, out).start();
         Thread.sleep(2000);
         new ThreadRead(readData, in).start();
     }
 }

再看看字符流示例：

 public class ReadData {

     public void readMethod(PipedReader reader) throws IOException{
         System.out.println("begin read...");
         char[] c = new char[20];
         int readLength = reader.read(c);
         while (readLength != -1) {
             String newData = new String(c, 0, readLength);
             System.out.println("read:"+newData);
             readLength = reader.read(c);
         }
         reader.close();
         System.out.println("end read...");
     }

 }

 public class WriteData {

     public void writeMethod(PipedWriter writer) throws IOException{
         System.out.println("begin write...");
         for (int i = 0; i < 10; i++) {
             writer.write((""+i));
             System.out.println("write:"+i);
         }
         writer.close();
         System.out.println("end write...");
     }
 }

 public class ThreadRead extends Thread {

     private ReadData readData;
     private PipedReader reader;

     public ThreadRead(ReadData readData, PipedReader reader) {
         this.readData = readData;
         this.reader = reader;
     }

     @Override
     public void run() {
         try {
             readData.readMethod(reader);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
 }

 public class ThreadWrite extends Thread {

     private WriteData writeData;
     private PipedWriter writer;

     public ThreadWrite(WriteData writeData, PipedWriter writer) {
         this.writeData = writeData;
         this.writer = writer;
     }

     @Override
     public void run() {
         try {
             writeData.writeMethod(writer);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
 }

 public class Run {
     public static void main(String[] args) throws IOException, InterruptedException {
         WriteData writeData = new WriteData();
         ReadData readData = new ReadData();

         PipedWriter writer = new PipedWriter();
         PipedReader reader = new PipedReader();

         writer.connect(reader);

         new ThreadWrite(writeData, writer).start();
         Thread.sleep(2000);
         new ThreadRead(readData, reader).start();
     }
 }