多线程补充

等待唤醒机制

现在有两条线程在运行，其中一条线程可以创造一个特殊的数据供另一条线程使用，但这个数据的创建也有要求：在同一时间只允许有一个这样的特殊数据，那么我们要怎样去完成呢？如果用普通的多线程在理想环境下（也就是两个线程分别每个抢到一次）可以完成，但是很多时候没有这么美好，如果任意一个线程连续运行就会发生错误。我们可以让线程在运行的时候去判断这个特殊数据是否存在，然后再去根据这个结果去运行程序或是放弃占用CPU让另一个线程运行就行了。

例子：

public class dask {//有就是1，没有就是0；public static int food=0;//消耗十次public static int sum=10;public static Object lock=new Object();
}

public class cread implements Runnable{@Overridepublic void run() {while(true){synchronized (dask.lock){if(dask.sum==0&&dask.food==0) {break;} else {if(dask.food==0){dask.food=1;System.out.println("做了一个数据");dask.lock.notifyAll();}else{try {dask.lock.wait();} catch (InterruptedException e) {throw new RuntimeException(e);}}}}}}
}

public class food implements Runnable{@Overridepublic void run() {while(true){synchronized (dask.lock){if(dask.sum==0&&dask.food==0) {break;} else {if(dask.food==1){dask.sum--;dask.food=0;System.out.println("还可以使用"+dask.sum+"次");dask.lock.notifyAll();}else{try {dask.lock.wait();} catch (InterruptedException e) {throw new RuntimeException(e);}}}}}}
}

public class Main {public static void main(String[] args) {food food=new food();Thread thread=new Thread(food);thread.start();cread cread=new cread();Thread thread1=new Thread(cread);thread1.start();}
}

网络编程

import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;public class TCPin implements Runnable{private final Socket socket;private final String name;public TCPin(Socket socket, String name) {this.socket = socket;this.name = name;}@Overridepublic void run() {TCPout tcPout=new TCPout(socket,name);Thread thread= new Thread(tcPout);thread.start();char []chars=new char[1000];while(true){InputStreamReader inputStreamReader= null;try {inputStreamReader = new InputStreamReader(socket.getInputStream());} catch (IOException e) {throw new RuntimeException(e);}int x;try {x=inputStreamReader.read(chars);} catch (IOException e) {throw new RuntimeException(e);}System.out.println(new String(chars,0,x));}}}

import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
import java.util.Scanner;public class TCPout implements Runnable{private final Socket socket;private final String name;public TCPout(Socket socket, String name) {this.socket = socket;this.name = name;}@Overridepublic void run() {Scanner scanner=new Scanner(System.in);OutputStream outputStream= null;try {outputStream = socket.getOutputStream();} catch (IOException e) {throw new RuntimeException(e);}while(true){String s=name+":\t"+scanner.nextLine();try {outputStream.write(s.getBytes());} catch (IOException e) {throw new RuntimeException(e);}}}}

import java.io.IOException;
import java.net.Socket;public class TCPclient {public static void main(String[] args) throws IOException {Socket socket = new Socket("127.0.0.1", 1080);TCPin tcPin=new TCPin(socket,"用户1");tcPin.run();}
}

import java.io.IOException;
import java.net.Socket;public class TCPclient1 {public static void main(String[] args) throws IOException {Socket socket = new Socket("127.0.0.1", 1080);TCPin tcPin=new TCPin(socket,"用户2");tcPin.run();}
}

import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;public class serverin implements Runnable{private final Socket socket;private final String name;public serverin(Socket socket, String name) {this.socket = socket;this.name = name;}@Overridepublic void run() {char []chars=new char[1000];while(true){InputStreamReader inputStreamReader= null;try {inputStreamReader = new InputStreamReader(socket.getInputStream());} catch (IOException e) {throw new RuntimeException(e);}int x;try {x=inputStreamReader.read(chars);} catch (IOException e) {throw new RuntimeException(e);}System.out.println(new String(chars,0,x));}}}

import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.Scanner;public class TCPserver {public static void main(String[] args) throws IOException {ServerSocket serverSocket=new ServerSocket(1080);ArrayList<Socket> s=new ArrayList<>();int x=0;while(true){Socket socket=serverSocket.accept();s.add(socket);System.out.println(x);Thread thread=new Thread(new serverin(socket,"服务器"));thread.start();x++;if(x==2)break;}Scanner scanner=new Scanner(System.in);OutputStream outputStream= null;while(true) {String b = "服务器" + ":\t" + scanner.nextLine();for (int i = 0; i < s.size(); i++) {try {outputStream = s.get(i).getOutputStream();} catch (IOException e) {throw new RuntimeException(e);}try {outputStream.write(b.getBytes());} catch (IOException e) {throw new RuntimeException(e);}}}}
}

该程序实现了多个客户端与服务端的多次通信。