3.6线程间的通信：字节流与字符流

最新推荐文章于 2024-05-16 20:42:28 发布

envieol

最新推荐文章于 2024-05-16 20:42:28 发布

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分类专栏：多线程

本文链接：https://blog.youkuaiyun.com/bb10210521/article/details/50541432

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本文探讨了线程间通信中字节流与字符流的使用，包括PipedInputStream、PipedOutputStream、PipedReader和PipedWriter。分析了字节流在读取时如果没有数据会堵塞线程，而字符流的使用方式与字节流类似，关键在于建立输入输出管道的连接。

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管道流（pipeStream）是一种特殊的流，用于线程间的通信。
字节流：PipedInputStream和PipedOutputStream
字符流：PipedReader和PipedWriter

字节流

package com.myObject;

import java.io.IOException;
import java.io.PipedInputStream;

public class ReadObj {
    public void readMothd(PipedInputStream is) {
        try {
            System.out.println("read begin");
            byte[] byteArr = new byte[20];
            int readLength;
            while ((readLength = is.read(byteArr)) != -1) {
                String str = new String(byteArr,0,readLength);
                System.out.println(str);
            }
            System.out.println("red end");
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

package com.myObject;

import java.io.IOException;
import java.io.PipedOutputStream;

public class WriteObj {
    public void writeMothd(PipedOutputStream os) {
        try {
            System.out.println("write begin");
            for(int i = 0; i < 50; i++){
                String str = ""+(1+i);
                os.write(str.getBytes());
            }
            System.out.println("write end");
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }
}

package com.myThread;

import java.io.PipedInputStream;

import com.myObject.ReadObj;

public class Thread1a extends Thread{
    private PipedInputStream is;
    private ReadObj readObj;

    public Thread1a(PipedInputStream is, ReadObj readObj) {
        this.is = is;
        this.readObj = readObj;
    }

    @Override
    public void run() {
        super.run();
        readObj.readMothd(is);
    }
}

package com.myThread;

import java.io.PipedInputStream;
import java.io.PipedOutputStream;

import com.myObject.ReadObj;
import com.myObject.WriteObj;

public class Thread1b extends Thread{
    private PipedOutputStream os;
    private WriteObj writeObj;

    public Thread1b(PipedOutputStream os, WriteObj writeObj) {
        this.os = os;
        this.writeObj = writeObj;
    }

    @Override
    public void run() {
        super.run();
        writeObj.writeMothd(os);
    }
}

package com.test;

import java.io.IOException;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;

import com.myObject.ReadObj;
import com.myObject.WriteObj;
import com.myThread.Thread1a;
import com.myThread.Thread1b;

public class Test1 {
    public static void main(String[] args){
        try {
            WriteObj writeObj = new WriteObj();
            ReadObj readObj = new ReadObj();
            PipedInputStream is = new PipedInputStream();
            PipedOutputStream os = new PipedOutputStream();

//      is.connect(os);//与下面效果一样，连接管道，如果对象与别的管道已经连接则抛出IO异常
            os.connect(is);

            Thread1a thread1a = new Thread1a(is, readObj);
            Thread1b thread1b = new Thread1b(os, writeObj);

            thread1a.start();
            Thread.sleep(3000);
            thread1b.start();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }


    }
}

打印结果
read begin write begin write end 12345678910111213141 51617181920212223242 52627282930313233343 53637383940414243444 54647484950 red end

分析：读取的线程先启动，但是没有流写入，所以线程被堵塞在readLength = is.read(byteArr)；直到有流写入，才继续往下执行

字符流

package com.test;

import java.io.IOException;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.io.PipedReader;
import java.io.PipedWriter;

import com.myObject.ReadObj;
import com.myObject.WriteObj;
import com.myThread.Thread1a;
import com.myThread.Thread1b;

public class Test1 {
    public static void main(String[] args){
        try {
            WriteObj writeObj = new WriteObj();
            ReadObj readObj = new ReadObj();
            PipedReader is = new PipedReader();
            PipedWriter os = new PipedWriter();

//      is.connect(os);//与下面效果一样，连接管道，如果对象与别的管道已经连接则抛出IO异常
            os.connect(is);

            Thread1a thread1a = new Thread1a(is, readObj);
            Thread1b thread1b = new Thread1b(os, writeObj);

            thread1a.start();
            Thread.sleep(3000);
            thread1b.start();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }


    }
}

package com.myObject;

import java.io.IOException;
import java.io.PipedOutputStream;
import java.io.PipedWriter;

public class WriteObj {
    public void writeMothd(PipedWriter os) {
        try {
            System.out.println("write begin");
            for(int i = 0; i < 50; i++){
                String str = ""+(1+i);
                //os.write(str.getBytes());
                os.write(str);
            }
            System.out.println("write end");
            os.close();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }
}

package com.myObject;

import java.io.IOException;
import java.io.PipedInputStream;
import java.io.PipedReader;

public class ReadObj {
    public void readMothd(PipedReader is) {
        try {
            System.out.println("read begin");
            //byte[] byteArr = new byte[20];
            char[] byteArr =new char[20];
            int readLength;
            while ((readLength = is.read(byteArr)) != -1) {
                String str = new String(byteArr,0,readLength);
                System.out.println(str);
            }
            System.out.println("red end");
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

package com.myThread;

import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.io.PipedWriter;

import com.myObject.ReadObj;
import com.myObject.WriteObj;

public class Thread1b extends Thread{
    private PipedWriter os;
    private WriteObj writeObj;

    public Thread1b(PipedWriter os, WriteObj writeObj) {
        this.os = os;
        this.writeObj = writeObj;
    }

    @Override
    public void run() {
        super.run();
        writeObj.writeMothd(os);
    }
}

package com.myThread;

import java.io.PipedInputStream;
import java.io.PipedReader;

import com.myObject.ReadObj;

public class Thread1a extends Thread{
    private PipedReader is;
    private ReadObj readObj;

    public Thread1a(PipedReader is, ReadObj readObj) {
        this.is = is;
        this.readObj = readObj;
    }

    @Override
    public void run() {
        super.run();
        readObj.readMothd(is);
    }
}

打印结果
read begin write begin write end 12345678910111213141 51617181920212223242 52627282930313233343 53637383940414243444 54647484950 red end

分析

字节流和字符流使用方式基本一样，最主要的地方是输入输出管道建立联系

//      is.connect(os);//与下面效果一样，连接管道，如果对象与别的管道已经连接则抛出IO异常
        os.connect(is);