EchoServer.java (阻塞模式)

Posted 2020-08-23

package block;
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;
import java.net.*;
import java.util.*;
import java.util.concurrent.*;

public class EchoServer {
  private int port=8000;
  private ServerSocketChannel serverSocketChannel = null;
  private ExecutorService executorService;
  private static final int POOL_MULTIPLE = 4;

  public EchoServer() throws IOException {
    executorService= Executors.newFixedThreadPool(
        Runtime.getRuntime().availableProcessors() * POOL_MULTIPLE);
    serverSocketChannel= ServerSocketChannel.open();
    serverSocketChannel.socket().setReuseAddress(true);
    serverSocketChannel.socket().bind(new InetSocketAddress(port));
    System.out.println("服务器启动");
  }

  public void service() {
    while (true) {
      SocketChannel socketChannel=null;
      try {
        socketChannel = serverSocketChannel.accept();
        executorService.execute(new Handler(socketChannel));
      }catch (IOException e) {
         e.printStackTrace();
      }
    }
  }

  public static void main(String args[])throws IOException {
    new EchoServer().service();
  }
}

class Handler implements Runnable{
  private SocketChannel socketChannel;
  public Handler(SocketChannel socketChannel){
    this.socketChannel=socketChannel;
  }
  public void run(){
    handle(socketChannel);
  }

  public void handle(SocketChannel socketChannel){
    try {
        Socket socket=socketChannel.socket();
        System.out.println("接收到客户连接，来自: " +
        socket.getInetAddress() + ":" +socket.getPort());

        BufferedReader br =getReader(socket);
        PrintWriter pw = getWriter(socket);

        String msg = null;
        while ((msg = br.readLine()) != null) {
          System.out.println(msg);
          pw.println(echo(msg));
          if (msg.equals("bye"))
            break;
        }
      }catch (IOException e) {
         e.printStackTrace();
      }finally {
         try{
           if(socketChannel!=null)socketChannel.close();
         }catch (IOException e) {e.printStackTrace();}
      }
  }

  private PrintWriter getWriter(Socket socket)throws IOException{
    OutputStream socketOut = socket.getOutputStream();
    return new PrintWriter(socketOut,true);
  }
  private BufferedReader getReader(Socket socket)throws IOException{
    InputStream socketIn = socket.getInputStream();
    return new BufferedReader(new InputStreamReader(socketIn));
  }

  public String echo(String msg) {
    return "echo:" + msg;
  }
}





/****************************************************
 * 作者：孙卫琴                                     *
 * 来源：<<Java网络编程精解>>                       *
 * 技术支持网址：www.javathinker.org                *
 ***************************************************/

 

EchoServer 类的构造负责创建线程池，启动服务器，把它绑定到一个本地端口。EchoServer类的service()方法负责接收客户的连接。每接收一个客户连接，就把它交给线程池来处理，线程池取出一个空闲的线程，来执行Handler对象的run()方法。Handler类的handle()负责与客户通信。该方法先获得与SocketChannel关联的Socket对象，然后从Socket对象中得到输入流与输出流，再接收和发送数据。
    SocketChanle实际上也是提供了read(ByteBuffer buffer),但是通过它来读取一行字符比较麻烦。一下radLine()方法就通过SocketChannel的read(ByteBuffer buffer)方法来读取一行字符串。它的作用与BufferReader的readLine()方法等价的。

 

 

//*******************

public String readLine(SocketChannel socketChannel)throws IOException{
    ByteBuffer buffer = ByteBuffer.allocate(1024);
    ByteBuffer tempBuffer =ByteBuffer.allocate(1);
    boolean isLine = false;
    boolean isEnd = false;
    String data = null;
    while(!isLine && !isEnd){
        tempBuffer.clear();
        int n = socketChannel.read(tempBuffer);
        if(n==-1){
            isEnd = true;
            break;
        }
        if(n==0) continue;
        tempBuffer.flip();
        buffer.put(tempBuffer);
        buffer.flip();
        Charset charset  = Charset.forName("GBK");
        CharBuffer charBuffer = charset.decode(buffer);
        data = charBuffer.toString();
        if(data.indexOf("\r\n")!=-1){
            isLine = true;
            data = data.substring(0,data.indexOf("\r\n"));
            break;
        }
        buffer.position(buffer.limit());
        buffer.limit(buffer.capacity());
    }
    return data;
}