Socket编程基础范例

   socket 通讯简单的说，就是服务器监听端口，客户端根据服务器地址和端口发出请求，服务器处理请求后返回数据给客户端。比如说，需要开发一个简单的qq聊天室，客户端发出各种请求，加好友，发消息，网络视屏等等。服务器进过处理后，可以将消息进行转发给不同的客户端。

   以下范例的目的是，从客户端发送数据，请求服务器执行指定方法，并且返回结果给客户端。 此范例一共包含3个java类。

 

   首先给出我们的数据传输对象，Message类。

   package sample;import java.util.HashMap;public class Message implements java.io.Serializable {private String methodName;private String param;public String getMethodName() {return methodName;}public void setMethodName(String methodName) {this.methodName = methodName;}public String getParam() {return param;}public void setParam(String param) {this.param = param;}}

 

   Message对象需要在网络中传输，因此必须可序列化，实现Serializable接口即可。简单起见，这个Message类只包装一个方法名，和一个String类型的参数。也就是说客户端指定一个方法名，并且提供一个String类型的参数，经过Message包装后，通过网络将请求数据传递给服务器。

 

   先简单看下 java.net.ServerSocket，此类负责监听服务器端指定端口，当端口接受请求后，立即建立与客户端的连接。以下使用ServerListener类来对ServerSocket类进行包装。

 

   package sample;import java.lang.reflect.InvocationTargetException;import java.net.*;import java.io.*;public class ServerListener {private int port;private java.net.ServerSocket serverSocket;public ServerListener() throws IOException {port = 10008;serverSocket = new ServerSocket(port);System.out.println("Server Listener Start ,local port = "+ serverSocket.getLocalPort());}private PrintWriter getWriter(Socket socket) throws IOException {OutputStream out = socket.getOutputStream();return new PrintWriter(out);}private BufferedReader getReader(Socket socket) throws IOException {InputStream in = socket.getInputStream();return new BufferedReader(new InputStreamReader(in));}private ObjectInputStream getObjectInputStream(Socket socket)throws IOException {InputStream in = socket.getInputStream();return new ObjectInputStream(in);}private ObjectOutputStream getObjectOutputStream(Socket socket)throws IOException {OutputStream out = socket.getOutputStream();return new ObjectOutputStream(out);}public void service() {while (true) {Socket socket = null;try {socket = serverSocket.accept();System.out.println("Connection established : IP = "+ socket.getInetAddress() + " Port = "+ socket.getPort());String result = "";Object object = null;while ((object = getObjectInputStream(socket).readObject()) != null) {result = handleEvent((Message) (object));getObjectOutputStream(socket).writeObject(result);}} catch (IOException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();} finally {try {serverSocket.close();} catch (IOException e) {e.printStackTrace();}}}}public String handleEvent(Message reqMsg) {String methodName = reqMsg.getMethodName();String param = reqMsg.getParam();String result = "";try {java.lang.reflect.Method method = getClass().getDeclaredMethod(methodName, new Class[] { String.class });System.out.println("Begin to invoke method " + methodName+ ",with param " + param);Object obj = method.invoke(this, new Object[] { param });result = obj.toString();System.out.println("After invoking method " + methodName);} catch (SecurityException e) {e.printStackTrace();} catch (NoSuchMethodException e) {e.printStackTrace();} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (InvocationTargetException e) {e.printStackTrace();}return result;}public String method1(String param) {return "It's the result !!!!";}public static void main(String[] args) {try {new ServerListener().service();} catch (IOException e) {e.printStackTrace();}}}

 

   此时启动main函数，ServerListener构造时初始化ServerSocket的一个实例，指定监听端口为 10008 。 

    

private java.net.ServerSocket serverSocket; public ServerListener() throws IOException {port = 10008;serverSocket = new ServerSocket(port);System.out.println("Server Listener Start ,local port = "+ serverSocket.getLocalPort()); }

 

  之后调用service()方法进行对端口的监听。

 

 public void service() {while (true) {Socket socket = null;try {socket = serverSocket.accept();System.out.println("Connection established : IP = "+ socket.getInetAddress() + " Port = "+ socket.getPort());String result = "";Object object = null;while ((object = getObjectInputStream(socket).readObject()) != null) {result = handleEvent((Message) (object));getObjectOutputStream(socket).writeObject(result);}} catch (IOException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();} finally {try {serverSocket.close();} catch (IOException e) {e.printStackTrace();}}}}

 

 

 

 

      socket = serverSocket.accept();  服务器此时会处于监听状态，如果没有任何请求，线程会一直阻塞于此。假设此时有客户端进行请求，则会立即与客户端建立连接，并且得到一个socket连接对象。这个对象处位于 java.net.Socket. 得到socket连接对象后，即可进行对输入输出流进行一系列操作已完成数据传输。建立连接后，如果输入流没有任何请求数据，线程会阻塞，直到客户端发送请求数据。当请求数据到达服务器端时，服务器端从输入流中获得序列化对象，即Message对象，然后拆包后，根据方法名和参数进行对服务器端方法的调用，然后得到结果，写入输出流，返回给客户端对象。

 

     最后给出客户端的java类，ClientListener.java 。

 

     package sample;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.OutputStream;import java.io.PrintWriter;import java.net.Socket;public class ClientListener {private String host;private int port;private Socket socket;public ClientListener() throws IOException {host = "192.168.80.118";port = 10008;socket = new Socket(host, port);}private PrintWriter getWriter(Socket socket) throws IOException {OutputStream out = socket.getOutputStream();return new PrintWriter(out);}private BufferedReader getReader(Socket socket) throws IOException {InputStream in = socket.getInputStream();return new BufferedReader(new InputStreamReader(in));}private ObjectOutputStream getObjectOutputStream(Socket socket)throws IOException {OutputStream out = socket.getOutputStream();return new ObjectOutputStream(out);}private ObjectInputStream getObjectInputStream(Socket socket)throws IOException {InputStream in = socket.getInputStream();return new ObjectInputStream(in);}private void service() {InputStreamReader in = new InputStreamReader(System.in);BufferedReader br = new BufferedReader(in);String command = "";String result = "";try {while ((command = br.readLine()) != null) {String methodName = (String) command.split(":")[0];String param = (String) command.split(":")[1];Message msg = new Message();msg.setMethodName(methodName);msg.setParam(param);getObjectOutputStream(socket).writeObject(msg);result = (String) getObjectInputStream(socket).readObject();System.out.println("The result from server after method invokation");System.out.println("Result is " + result);}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} finally {try {socket.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}public static void main(String[] args) {try {new ClientListener().service();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}

 

 如果此时启动main函数，则会立即与服务器建立socket连接。在ClientListener类初始化的时候，已经实例化socket连接对象，指定服务器端地址和监听端口，并请求与服务器端的连接。建立连接后，客户端从命令行采集数据，如：method1:param1. 数据会被封装到Message对象，并且序列化后，通过之前建立起来的socket通道，传输到服务器端。这样就完成了客户端的数据采集和请求。其实，当从输入流获取返回结果时，客户端线程会阻塞等待服务器端的响应结果。服务器处理完毕，返回结果后，客户端立即打印出返回结果。

 

 

此范例执行过程：1，启动ServerListener，服务器端控制台显示 Server Listener Start ,local port = 10008

                        2，启动ClientListener,服务器控制台显示    Server Listener Start ,local port = 10008
                             Connection established : IP = /192.168.80.118 Port = 50360          

                        3，客户端控制台输入 ：  method1:param1 .  服务器端显示 ： 

                              Begin to invoke method method1,with param param1
                              After invoking method method1 

                        4，客户端显示：

                             The result from server after method invokation
                             Result is It's the result !!!!

 

 

 To be continue ......