java为什么可以部署到不同的服务器上正常运行？

楼主要搞清楚一些概念：

1 Java的跨平台是指java应用程序可以运行在windows、linux等操作系统上，而这种跨平台性是通过JVM（java虚拟机）来实现的。

2 而Java EE应用可以部署到tomcat,Weblogic等Web服务器上运行是因为那些Web服务器实现了Java EE规范（servlet、jsp规范等）。

服务器端可以采用多线程处理客户请求，例如：

package threadPool;

import javaioBufferedReader;

import javaioIOException;

import javaioInputStream;

import javaioInputStreamReader;

import javaioOutputStream;

import javaioPrintWriter;

import javanetServerSocket;

import javanetSocket;

import javautilconcurrentExecutorService;

import javautilconcurrentExecutors;

public class ThreadPoolServer {

private int port = 8000;

private ServerSocket serverSocket;

private ExecutorService executorService; //线程池

private final int POOL_SIZE = 4; //单个CPU时线程池中的工作线程数目

public ThreadPoolServer() throws IOException{

serverSocket = new ServerSocket(port);

//创建线程池

//Runtime 的availableProcessors()方法返回当前系统CPU的数目

//系统CPU越多，线程池中的工作线程数目越多

executorService = ExecutorsnewFixedThreadPool(RuntimegetRuntime()availableProcessors()POOL_SIZE);

Systemoutprintln("服务器已启动！！");

}

public void service(){

while(true){

Socket socket = null;

try{

socket = serverSocketaccept();

executorServiceexecute(new Handler(socket));

}catch(IOException e){

eprintStackTrace();

}

}

}

public static void main(String[] args) {

try {

new ThreadPoolServer()service();

} catch (IOException e) {

eprintStackTrace();

}

}

}

class Handler implements Runnable {

private Socket socket;

public Handler(Socket socket) {

thissocket = socket;

}

private PrintWriter getWriter(Socket socket) throws IOException {

OutputStream socketOut = socketgetOutputStream();

return new PrintWriter(socketOut, true);

}

private BufferedReader getReader(Socket socket) throws IOException {

InputStream socketIn = socketgetInputStream();

return new BufferedReader(new InputStreamReader(socketIn));

}

public String echo(String msg) {

return "echo:" + msg;

}

@Override

public void run() {

try {

Systemoutprintln("New connection accepted:" + socketgetInetAddress() + ":" + socketgetPort());

BufferedReader br = getReader(socket);

PrintWriter pw = getWriter(socket);

String msg = null;

while ((msg = brreadLine()) != null) {

Systemoutprintln(msg);

pwprintln(echo(msg));

if (msgequals("bye")) {

break;

}

}

} catch (IOException e) {

eprintStackTrace();

} finally {

try {

if (socket != null)

socketclose();

} catch (IOException e) {

eprintStackTrace();

}

}

}

}