基础知识
每个正在系统上运行的程序都是一个进程（process）。每个进程包含一到多个线程(thread)。进程也可能是整个程序或者是部分程序的动态执行。
线程是一组指令的集合，或者是程序的特殊段，它可以在程序里独立执行。也可以把它理解为代码运行的上下文。所以线程基本上是轻量级的进程，它负责在单个程序里执行多任务。
Java对多线程的支持是非常强大的，他屏蔽掉了许多的技术细节，让我们可以轻松的开发多线程的应用程序。Java里面有2个方法实现多线程，
1 继承 Thread类，比如
class MyThread extends Thread {
public void run() {
// 这里写上线程的内容
}
public static void main(String[] args) {
// 使用这个方法启动一个线程
new MyThread().start();
}
}
2 实现 Runnable接口，例如
class MyThread implements Runnable{
public void run() {
// 这里写上线程的内容
}
public static void main(String[] args) {
// 使用这个方法启动一个线程
new Thread(new MyThread()).start();
}
}
一般鼓励使用第二种方法，因为Java里面只允许单一继承，但允许实现多个接口。第二个方法更加灵活。
代码示例
多线程实现1－30的累计，其中共享资源池为1－30的数字的递增，采用了同步锁synchronized。
1 class Sum{ //共享资源，计数器count
2 private int count;//共享资源
3 public int add(){
4 synchronized(this){ //代码段1，共享锁，修饰程序段或者方法
5 count = count + 1;
6 System.out.println("add:" + count);
7 return count;
8 }
9 }
10 }
11 class SumThread implements Runnable{//定义线程
12 private Sum sd;
13 private int sum = 0;
14 private int [] a = new int[10];
15
16 public SumThread(String name, Sum sd){
17 super(name);
18 this.sd = sd;
19 }
20 public void run(){//必需的重写
21 try{
22 for(int i=0;i<10;i++){
23 a[i] = sd.add();
24 sum += a[i];
25 Thread.sleep(100);
26 }
27 Thread.sleep(1000);
28 }catch(Exception e){}
29
30 System.out.println(getName() + "累加和:" + sum);
31 }
32 public void showData(){
33 System.out.print(getName() + "获得的数为");
34 for(int i=0;i<10;i++){
35 if(i%10==0)System.out.println();
36 System.out.print(a[i] + "+\t");
37 }
38 }
39 public int getSum(){
40 return sum;
41 }
42 }
43 public class SumDemo{
44 public static void main(String [] args){
45 Sum sd = new Sum();//代表共享资源的变量
46 SumThread s1 = new SumThread("线程1",sd);//创建完毕
47 SumThread s2 = new SumThread("线程2",sd);
48 SumThread s3 = new SumThread("线程3",sd);
49 Thread st1 = new Thread(s1);
50 Thread st2 = new Thread(s2);
51 Thread st3 = new Thread(s3);
52 st1.setPriority(Thread.MAX_PRIORITY); //代码段2
53 st2.setPriority(10);
54 st3.setPriority(1);
55 long begin = System.currentTimeMillis();
56 st1.start();//使线程运行
57 st2.start(); st3.start();
58 St1.join(); st2.join(); st3.join();
59 st1.showData();
60 st2.showData();
61 st3.showData();
62 System.out.println("总和为:" + (st1.getSum() + st2.getSum() + st3.getSum()));
63 long end = System.currentTimeMillis();
64 System.out.println(“探测localhost的TCP端口，共耗时” +
65 ( end - begin)+"毫秒");
66 } }
TCP Socket多线程通信
服务端：
1 import java.io.*;
2 import java.net.*;
3 import java.util.*;
4 @SuppressWarnings(value={"deprecation","unchecked"}) //查阅该语句作用
5 public class MultiServer extends Thread{
6 ServerSocket serverSocket = null;
7 boolean listening = true;
8 int port = 1080;
9 int count;
10 public MultiServer(){
11 try{
12 serverSocket = new ServerSocket(port);
13 System.out.println("The Chat Server is listening on " + port);
14 }catch(IOException e){
15 System.err.println("Can‘t listen on Port");
16 System.exit(1);
17 }
18 count = 0;
19 while(listening){
20 try{
21 new ClientServiceThread(serverSocket.accept()).start();
22 count += 1;
23 System.out.println("The Chat Server get " + count + " Clients");
24 }catch(IOException e){
25 System.err.println("Can‘t Accept the Client Connection Apply");
26 }
27 }
28 try{
29 serverSocket.close();
30 }catch(IOException e){
31 System.exit(1);
32 }
33 this.start();
34 }
35 public static void main(String args[]){
36 MultiServer ms = new MultiServer();
37 } }
客户端：
1 class ClientServiceThread extends Thread{
2 private String name = "Client";
3 private Socket socket = null;
4 private Vector clients = null;
5 public ClientServiceThread(Socket socket){
6 super("ClientServiceThread");
7 this.socket = socket;
8 }
9 public ClientServiceThread(Vector clients, Socket socket){
10 super("ClientServiceThread");
11 this.socket = socket;
12 this.clients = clients;
13 }
14 public void run(){
15 try{
16 DataInputStream in = new DataInputStream(new
17 BufferedInputStream(socket.getInputStream()));
18 PrintStream out = new PrintStream(new
19 BufferedOutputStream(socket.getOutputStream(), 1024), true);
20
21 String inputLine, outputLine;
22
23 GreetingProtocol greeting = new GreetingProtocol();
24 outputLine = greeting.processInput(null);
25
26 out.println("Welcome to My Chat Server, Please REG your Name, Format: name = yourname");
27 out.flush();
28
29 while((inputLine = in.readLine()) != null){
30 System.out.println(this.name + " Say: " + inputLine);
31 if(inputLine.startsWith("name")){
32 this.name =
33 inputLine.substring(inputLine.indexOf("=") + 1);
34 out.println("Your Name "+ this.name + " is REG");
35 out.flush();
36 }else{
37 outputLine = greeting.processInput(inputLine);
38 out.println(outputLine);
39 out.flush();
40 }
41 if(inputLine.equals("bye")) break;
42 }
43 out.close();
44 in.close();
45 socket.close();
46 }catch(IOException e){
47 e.printStackTrace();
48 } } }
原文地址：https://www.cnblogs.com/ftl1012/p/9347677.html
时间： 2024-10-18 02:59:54