急!!socket网络编程问题,在线!

while(true){
        try{
            clientSentence = new String(inFromClient.readLine());
            outToClient.writeBytes("OK\r\n");
          }
      catch(IOException ex){
        }其中clientSentence 是String，
inFromClient =new BufferedReader(new InputStreamReader(connectedSocket.getInputStream()));
outToClient = new DataOutputStream(connectedSocket.getOutputStream());connectedSocket是当前的连接

你说的聊天室功能应该用组播来实现，建议你看看《Beginning Java Networking》，Chad Darby,John Griffin等著。电子工业出版社有中文版，《Java网络编程指南》。

看一下这个我写的：/*this applet is used to request and receive the updated price information
*from the server side and display it in the applet window. The applet display
*the information using an animation.
*/import javax.swing.JApplet;import java.applet.*;
import java.awt.*;
import java.awt.image.BufferedImage;import java.net.*;
import java.io.*;
import javax.swing.JOptionPane;import java.text.DecimalFormat;
public class Client extends JApplet implements Runnable
{
  protected Socket socket; //socket connecting the server side
  protected DataInputStream input;
  protected DataOutputStream output;
  //horizontal position on the applet canvas where the string is displayed
  protected int horiPos;  private Image bufImage; //buffered image for offscreen drawing
  private Graphics graphic;
  protected Thread thread; //thread object
  //protected String[] stockNames = {"MSFT", "HSBC", "DELL", "IBM", "INTC", "SUN"};
  //protected String[] stockPrices = {"27.5", "82.3", "25.2", "85.5", "18.8", "5.7"};
  protected String[] stockNames = new String[6];
  protected String[] stockPrices = new String[6];
  private int width; //width of the canvas
  private int height; //height of the canvas
  private int currentStringLength;  protected FontMetrics metrics;
  protected Font nameFont, priceFont; //fonts for different strings
  //constructor
  public Client()
  {
    //get the values of canvas of this applet
    width = 350;
    height = 150;
    horiPos = width;

    nameFont = new Font("Helvetica", Font.BOLD, 20);
    priceFont = new Font("Helvetica", Font.BOLD, 12);
  }  //this method wait until the display is finished and then get the
  //image resource of the display based on the finished screen show
  public void addNotify()
  {
   super.addNotify();
   bufImage = this.createImage(width, height);
    graphic = bufImage.getGraphics();
    metrics = graphic.getFontMetrics();
  }
    //init method
  public void init()
  {
    //get the server host from the paramters in html file
    String host = getParameter("Host");
    if (host == null) {
      host = "127.0.0.1";
    }    try {
      //set the socket connection to the server
      socket = new Socket(host, 9999);
      //get the dataInputStream and outputstream from the connection
      input = new DataInputStream(socket.getInputStream());
      output = new DataOutputStream(socket.getOutputStream());
    }
    catch (UnknownHostException uhe) {
      System.err.println("Unknown Host Error!");
    }
    catch (SocketException se) {
      System.err.println("Socket Error!");
    }
    catch (IOException ioe) {
      System.err.println("IO Error!");
    }

    //create a thread using this object
    thread = new Thread(this);
    thread.start();
  }  //run method
  public void run()
  {
    //first time for updating stock information
    try{
     updateStockInformation();
}catch(IOException ioe){
System.err.println("IOException");
ioe.printStackTrace();
}

    while(true)
    {
      repaint();      try{
        Thread.currentThread().sleep(100L);
      }catch(InterruptedException ie){
        System.err.println("Interrupted Exception During the Sleep Method");
      }

      //the displayed string moves leftward by 4 pixles for each loop round
      horiPos -= 4;

      //if the displayed string has reached the left side edge
      //then the program should wait for a while and at the same
      //update the stock price information downloaded from the server
      if(horiPos + currentStringLength < 0){
        try{
          Thread.currentThread().sleep(400L);
          horiPos = width;
          updateStockInformation();
        }catch(InterruptedException ie){
          System.err.println("Interrupted Exception during waiting");
        }catch(IOException e){
          System.err.println("IO Exception during the updating process");
        }
      }
    }
  }
  //this method gets the stock names and prices from the server from the inputstream
  public void updateStockInformation() throws IOException
  {
    //send the request for updated price info
    output.writeBoolean(true);
    output.flush();    for(int i=0; i<stockNames.length; i++)
    {
      stockNames[i] = input.readUTF();
      //format mask the price info
      stockPrices[i] = input.readUTF();
    }
  }


  //update method overridden
  public void update(Graphics g)
  {
   //call for resizing function when the size of the canvas is changed
   resizing();
   clearCanvas(graphic);
   paint(graphic);
   g.drawImage(bufImage, 0, 0, this);
  }  //paint method overridden
  public void paint(Graphics g)
  {
    drawString(g);
  }  //clear the display of the canvas
  protected void clearCanvas(Graphics g)
  {
    g.clearRect(0, 0, width, height);
  }


  //if the applet window is resized then we need to update the size information
  public void resizing()
  {
   Dimension size = this.getSize();
   if(size.getWidth() > 0 && size.getHeight() > 0)
   {
     width = (int)size.getWidth();
     height = (int)size.getHeight();
    }

    //create the new iamge resources based on the new screen resources
   graphic.dispose();
   bufImage = this.createImage(width, height);
   graphic = bufImage.getGraphics();
  }
  //draw method that is used to draw the graphics on the offscreen image
  protected void drawString(Graphics g)
  {
    //the length of the string
    int stringLength = 0;
    int temp;    for(int i=0; i<stockNames.length; i++)
    {
      //draw stock names
      g.setColor(Color.blue);
      g.setFont(nameFont);
      g.drawString(stockNames[i], (horiPos + stringLength), height/2-5);

      metrics = g.getFontMetrics();
      temp = metrics.stringWidth(stockNames[i]);
      stringLength = stringLength + temp + 1;      //draw stock prices
      g.setColor(Color.red);
      g.setFont(priceFont);
      g.drawString(stockPrices[i], (horiPos + stringLength), (height/2-28)+metrics.getHeight());      metrics = g.getFontMetrics();
      temp = metrics.stringWidth(stockPrices[i]);
      stringLength = stringLength + temp + 25;
    }    currentStringLength = stringLength - 32;
  }}

服务器端/*This class is server-side listener and deal with the incoming connections
*sending back the reply to the client containing updated stock prices.
*/import java.net.ServerSocket;
import java.net.Socket;import java.io.DataOutputStream;
import java.io.DataInputStream;
import java.io.IOException;import java.text.DecimalFormat;public class Server
{
  protected Socket socket;
  protected DecimalFormat format;
  //constructor
  public Server(Socket socket) {
    this.socket = socket;
    this.format = new DecimalFormat("###0.0#");
  }
    //override the run method of the thread
  public void start() {
    DataOutputStream output = null;
    DataInputStream input = null;    try{
      //get the io streams from the socket
      output = new DataOutputStream(socket.getOutputStream());
      input = new DataInputStream(socket.getInputStream());      boolean request = false;      try {
        do {
          System.out.println();          //wait for the request for updated price info from client side
          request = input.readBoolean();

          //send the updated stock price info
          if (request == true) {
            String[] names = Stock.getNames();
            double[] prices = Stock.getPrices();
            String temp;
            //send the updated info via the output stream
              for (int i = 0; i < names.length; i++) {
                output.writeUTF(names[i]);
                System.out.print(names[i] + "  ");
                temp = format.format(prices[i]);
                output.writeUTF(temp);
                System.out.println(temp);
              }
              output.flush();
            }
        } while (true);
      }
      catch (IOException ioe) {
          System.err.println("Could not send price info");
      }
      //finally block to ensure that the iostreams and socket are closed
      finally{
       input.close();
       output.close();
       socket.close();
        System.err.println();
        System.err.println("Client side disconnected. Server stopped.");
      }
    }catch(IOException ioe){
      System.err.println("Failure in intializing IO stream");
    }
  }
  //main method
  public static void main(String[] args)
  {
    ServerSocket server = null;
    Socket socket;    try{
    //create the server socket listening at port 9999
      server = new ServerSocket(9999);
      System.err.println("\nServer started...");
    }catch(IOException ioe){
      System.err.println("Failure in server socket initialization");
    }    try{
      if(server != null)
      {
        socket = server.accept(); //block and wait for the incoming connection
        System.err.println("Incoming connection from "
         + socket.getInetAddress() + " at "
         + 9999 + " accepted!");
        //deal with the connection incoming
        new Server(socket).start();
      }
    }catch(IOException ioe){
      System.err.println("Failure in accepting incoming connection");
    }
  }
}

服务器Sockets服务器并不是主动地建立连接.相反地,他们是被动地监听一个客户端的连接请示然后给他们服务.服务器是由类ServerSocket来建立的.下面的程序建立了一个服务器端socket并把它绑定到80端口:ServerSocket serverSocket = new ServerSocket(80, 5); 第一个参数是服务器要监听的端口.第二个参数是可选的.API文档中说明了这是一个监听时间,但是在传统的socket程序中第二个参数是监听深度.一个服务器可以同时接收多个连接请求,但是每次只能处理一个.监听堆是一个无回答的连接请求队列.上面的请求建立一个连接来处理最后五个请求.如果省略了后面的一个参数,则默认值是50.ServerSocket serverSocket = new ServerSocket(80, 5); 一旦socket建立了并开始监听连接,进来的连接将会建立并放在监听堆.accetp()方法把在堆中的连接取出来.Socket clientSocket = serverSocket.accept(); 这个方法返回一个用来与来访者对话的客户端连接.服务器本身不可能建立对话,相反地,服务器socket会使用accept()方法来产生一个新的socket.服务器socket依旧打开并排列新的连接请求.与客户端socket一样,下面的一步建立输入和输出流:DataInputStream inbound = new DataInputStream( clientSocket.getInputStream() ); DataOutputStream outbound = new DataOutputStream( clientSocket.getOutputStream() ); 一般的I/O操作可以在新建的流中运用.在服务器回应前它等待客户端发送一个空白的行.当会话结束时,服务器关闭流和客户端socket.如果在队列中没有请示将会出现什么情况呢?那个方法将会等待一个的到来.这个行为叫阻塞.accept()方法将会阻塞服务器线程直到一个呼叫到来.当5个连接处理完闭之后,服务器退出.任何的在队列中的呼叫将会被取消. 所有的服务器都要有以下的基本的步骤:1.建立一个服务器socket并开始监听.2.使用accept()方法取得新的连接. 3.建立输入和输出流.4.在已有的协议上产生会话. 5.关闭客户端流和socket.6.回到第二步或者到第七步.7.关闭服务器socket.

服务器Sockets列表9.2是一个服务器应用程序的一部分.列表9.2 一个简单的服务器程序 /**
* 一个监听端口并提供HTML文档的程序.
*/
class SimpleWebServer {
public static void main(String args[])
{
ServerSocket serverSocket = null;
Socket clientSocket = null;
int connects = 0;
try
{
{
// 建立一个服务器socket
serverSocket = new ServerSocket(80, 5);
while (connects < 5)
{
// 等待连接
clientSocket = serverSocket.accept();
//服务连接
ServiceClient(clientSocket);
connects++;
}
serverSocket.close();
}
catch (IOException ioe)
{
System.out.println("Error in SimpleWebServer: " + ioe);
}
}
public static void ServiceClient(Socket client)
throws IOException
{
DataInputStream inbound = null;
DataOutputStream outbound = null;
try
{
// 得到IO流
inbound = new DataInputStream( client.getInputStream());
outbound = new DataOutputStream( client.getOutputStream());
//格式化输出(回应头和很少的HTML文档)
StringBuffer buffer = PrepareOutput();
String inputLine;
while ((inputLine = inbound.readLine()) != null)
{
//如果到了HTTP请求的尾部,就发送回应
if ( inputLine.equals("") )
{
outbound.writeBytes(buffer.toString());
break;
}
}
}
finally
{
// 清除
System.out.println("Cleaning up connection: " + client);
tln("Cleaning up connection: " + client);
outbound.close();
inbound.close();
client.close();
client.close();
}
}

重复和并发服务器所有的这些调用都可以掷出一个UnknownHostException违例.如果一台计算机没有连接上DNS服务器,或者主机的确没有找到,这个违例就会被掷出.如果一台计算机没有一个激活的TCP/IP配置,getLocalHost()也为失败并掷出一个违例. 一旦一个地址被确定了,数据报就可以被送出了.下面的程序传输了一个字符串给目的socket: String toSend = "This is the data to send!");
byte[] sendbuf = new byte[ toSend.length() ];
toSend.getBytes( 0, toSend.length(), sendbuf, 0 );
DatagramPacket sendPacket = new DatagramPacket( sendbuf, sendbuf.length,
addr, port);
clientSocket.send( sendPacket ); 首先,字符串必须被转换成一个字节数组.然后,一个新的DatagramPacket实例必须被建立.注意构建器的最后两个参数.因为要发送一个包,所以地址和端口必须被给定.一个applet可能可以知道它的服务器的地址,但是服务器如何知道它的客户机的地址呢.当任何一个包被收到后,返回的地址和端口会被解压出来,并通过getAddress()和getPort()方法得到.这就是一个服务器如何回应一个客户端的包: DatagramPacket sendPacket = new DatagramPacket( sendbuf, sendbuf.length,
recvPacket.getAddress(), recvPacket.getPort() );
serverSocket.send( sendPacket ); 不像面向连接的操作,数据报服务器服务器其实比数据报客户端更简单: 数据报服务器一个数据报服务器的基本步骤: 1.在一个指定的端口上建立一个数据报socket. 2.用receive方法等待进来的包.3.用特定的协议来回应收到的包.4.回到第二步或继续第二步.5.关闭数据报socket.列表9.3演示了一人简单的数据报回应服务器.它将回应它收到的包. 列表9.3.一个简单的数据报回应服务器 import java.io.*;
import java.net.*;
public class SimpleDatagramServer
{
public static void main(String[] args)
{
DatagramSocket socket = null;
DatagramPacket recvPacket, sendPacket;
try
{
socket = new DatagramSocket(4545);
while (socket != null)
{
recvPacket= new DatagramPacket(new byte[512], 512);
socket.receive(recvPacket);
sendPacket = new DatagramPacket(
recvPacket.getData(), recvPacket.getLength(),
recvPacket.getAddress(), recvPacket.getPort() );
socket.send( sendPacket );
}
}
catch (SocketException se)
{
System.out.println("Error in SimpleDatagramServer: " + se);
}
catch (IOException ioe)
{
System.out.println("Error in SimpleDatagramServer: " + ioe); 这个应用程序被当作一个重复的服务器.因为它只有在处理完一个进程以后才会接受另一个连接.更多的复杂服务器是并发的.它为每一个请求分配一个线程,而不是来一个处理一个.所以看起来它在同时处理多人请求.所有的商业的服务器都是并发的服务器. Java数据报类不像面向连接的类,数据报的客户端和服务器端的类在表面上是一样的.下面的程序建立了一个客户和服务器商的数据报sockets:DatagramSocket serverSocket = new DatagramSocket( 4545 );
DatagramSocket clientSocket = new DatagramSocket(); 服务器用参数4545来指定端口号,由于客户端将要呼叫服务器,客户端可以利用可利用的端口.如果省略第二个参数,程序会让操作系统分配一个可用的端口.客户端可以请求一个指定的端口,但是如果其它的应用程序已经绑定到这个端口之上,请求将会失败.如果你的意图不是作为一个服务器,最好不要指定端口.由于流不能由交谈得到,那么我么如何与一个数据报Socket进行对话.答案在于数据报类. 接收数据报DatagramPacket类是用来通过DatagramSocket类接收和发送数据的类.packet类包括了连接信息和数据.就如前面所说的一样,数据报是自身独立的传输单元.DatagramPacket类压缩了这些单元.下面的程序表示了用一个数据报socket来接收数据:DatagramPacket packet = new DatagramPacket(new byte[512], 512); clientSocket.receive(packet);
clientSocket.receive(packet); packet的构建器需要知道将得到的数据放在哪儿.一个512字节的缓存被建立并且作为构建器的第二个参数.每二个构建器参数是缓存的大小.就像ServerSocket类的accept()方法一样,receive()方法在数据可用之前将会阻塞.发送数据报发送数据报是非常地简单地,所有需要的只是一个地址.地址是由InetAddress类来建立的.这个类没有公共的构建器,但是它有几个static的方法,可以用来建立这个类的实例.下面的列表列出了建立InetAddress类的实例的方法: Public InetAddress Creation Methods InetAddress getByName(String host);
InetAddress[] getAllByName(String host);
InetAddress getLocalHost(); 得到本地主机的地址是非常地有用的,只有前面两个方法是用来发送数据包的.getByName()和getAllByName()需要目的主机的地址.第一个方法仅仅只是返回第一个符合条件的东西.第二个方法是必须的,因为一台计算机可能有多个地址.在这种情况下,这台计算机被称为multi-homed.所有的建立的方法都被标记为static.它们必须像下面这样得到调用: InetAddress addr1 = InetAddress.getByName("merlin");
InetAddress addr2[] = InetAddress.getAllByName("merlin");
InetAddress addr3 = InetAddress.getLocalHost();

需要的stock类但是没必要了解/*this class is used to calculate the stock price according to the model given
*by the problem. The price info will be updated each round.
*/ public class Stock
{
//the possibilities of changes for different stocks
private static double [][] possibility = {{0, 0.60, 0.85, 0.95, 1.00},
   {0, 0.50, 0.75, 0.90, 1.00},
   {0, 0.40, 0.65, 0.85, 1.00},
   {0, 0.30, 0.60, 0.85, 1.00}};
//percentage change compared with the original price
private static double [] changes = {0, 0.01, 0.03, 0.05};
//betas of these stocks
private static double [] betas = {1.0, 1.3, 1.3, 1.6, 2.0, 2.0};
private static double [] prices = {27.50, 82.30, 25.20,
  85.50, 18.80, 5.70}; //prices
static String [] stockNames = {"MSFT", "HSBC", "DELL",
   "IBM", "INTC", "SUN"}; //stock names


//update the prices of all the given stocks
protected static void updatePrices()
{
for(int i=0; i<prices.length; i++)
{
prices[i] = calculatePrice(prices[i], betas[i]);
}
}

//getter method for stock prices
public static double [] getPrices()
{
double [] temp = prices;
updatePrices();
return temp;
}

//getter method for stock names
public static String [] getNames()
{
return stockNames;
}

//this static method is used to calculate the forecast stock price
//using the input arguments of original price and beta of the stock
protected static double calculatePrice(double originalPrice, double beta)
{
double percentage = (Math.abs(Math.random()-0.5))*2;
double direction = Math.random()-0.5;
double changePer = 0;

int i;
if(beta == 1.0)      { i = 0; }
else if(beta == 1.3) { i = 1; }
else if(beta == 1.6) { i = 2; }
else if(beta == 2.0) { i = 3; }
else                 { i = -1; }

//find the interval in which the possibility falls
if(i != -1){
for(int p=0; p < (possibility[i].length)-1; p++){
if(percentage >= possibility[i][p] && percentage < possibility[i][p+1]){
changePer = changes[p];
}
}
}

//calculate and return the new price
if(direction >= 0){
return originalPrice*(1+changePer);
}else
{
return originalPrice*(1-changePer);
}
}//end of calculatePrice method
}

简单的WEB服务器一个简单的WEB服务器将由列表9.2这样构建.当然,还必须要对方法和回应事件进行改进.简单的服务器不会分析和存储请求头.新的WEB服务器将分析和存储请求,为以后的处理作准备.为了达到这个目的,你必须有一个包含HTTP请求的类.HTTPrequest类列表9.5列出了一个完整的HTTPrequest类.这个类必须包括一个请求头所需的所有信息. 列表9.5.HTTPrequest类. import java.io.*;
import java.util.*;
import java.net.*;
import NameValue;
/**
* 这个类有一个HTTP请求的所有信息
*/
public class HTTPrequest
{
public String version;
public String method;
public String file;
public Socket clientSocket;
public DataInputStream inbound;
public NameValue headerpairs[];
/**
* 建立一个这个类的实例
*/
public HTTPrequest()
{
version = null;
method = null;
file = null;
clientSocket = null;
inbound = null;
inbound = null;
headerpairs = new NameValue[0];
}
/**
* 加入一个名称/值对到核心数组
*/
public void addNameValue(String name, String value)
{
try
{
NameValue temp[] = new NameValue[ headerpairs.length + 1 ];
System.arraycopy(headerpairs, 0, temp, 0, headerpairs.length);
temp[ headerpairs.length ] = new NameValue(name, value);
headerpairs = temp;
}
catch (NullPointerException npe)
{
System.out.println("NullPointerException while adding name-value:
" + npe);
}
}
/**
* 以字符串的形式归还这个类
*/
public String toString()
{
String s = method + " " + file + " " + version + "\n";
for (int x = 0; x < headerpairs.length; x++ )
s += headerpairs[x] + "\n";
return s;
}
} NameValue类简单地存储了两个字符串:name 和 value.当一个新的对要被加入时,一个新的数组将被分配.新的数组接受了旧的数组和新的成员.旧的数组然后被一个新建的对象覆盖了.

用URLConnection是不错的选择！！

服务端监听请求socket.accept()
收到请求后,读客户端输入信息,
向客户端发送反馈信息.

调试易

急!!socket网络编程问题,在线!

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