J2ME中使用Socket开发联网程序
2010-09-15 19:53
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源自:http://www.builder.com.cn/2007/1228/692426.shtml)
首先看一下,ServerSocketConnection类,它的一个非常重要的方法就是acceptAndOpen()方法,这个方法返回一个SocketConnection实例,从而使得客户端和服务器端可以通过socket通信了。典型的代码如下:
其实我们在用socket编写程序的时候无非遵循这样的一种规则:服务器端建立监听端口等待连接,客户端通过open()方法与服务器端建立连接,两端通过建立的socket传输数据,关闭连接。
下图是我在运行WTK中NetworkDemo的时候的截图!代码也一并发表出来。
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J2ME中使用Socket开发联网程序
开发者在线 Builder.com.cn 更新时间:2007-12-28作者:mingjava 来源:J2ME开发网
本文关键词: J2ME socket 联网程序
在J2ME中基于UDP协议编程一文中介绍了如何使用Datagram和DatagramConnection来开发应用程序,本文将主要讲述在MIDP2.0中使用ServerSocketConnection和SocketConnection来开发联网应用程序。TCP协议是可以保证传输的质量的,这也是他和UDP的一大区别。由于以上谈到的四个类都属于GCF,他们在程序编写方面也非常相似,通常我们在Server端的某个端口监听,当客户端连接服务器的时候,则可以得到一个SocketConnection的实例。通过两端的SocketConnection则可以实现C/S结构的通信了。首先看一下,ServerSocketConnection类,它的一个非常重要的方法就是acceptAndOpen()方法,这个方法返回一个SocketConnection实例,从而使得客户端和服务器端可以通过socket通信了。典型的代码如下:
// Create the server listening socket for port 1234 ServerSocketConnection scn = (ServerSocketConnection) Connector.open("socket://:1234"); // Wait for a connection. SocketConnection sc = (SocketConnection) scn.acceptAndOpen(); // Set application specific hints on the socket. sc.setSocketOption(DELAY, 0); sc.setSocketOption(LINGER, 0); sc.setSocketOption(KEEPALIVE, 0); sc.setSocketOption(RCVBUF, 128); sc.setSocketOption(SNDBUF, 128); // Get the input stream of the connection. DataInputStream is = sc.openDataInputStream(); // Get the output stream of the connection. DataOutputStream os = sc.openDataOutputStream(); // Read the input data. String result = is.readUTF(); // Echo the data back to the sender. os.writeUTF(result); // Close everything. is.close(); os.close(); sc.close(); scn.close(); .. SocketConnection的使用也是非常简单,通过Connector的open方法我们可以得到一个SocketConnection的实例。 SocketConnection sc = (SocketConnection) Connector.open("socket://host.com:79"); sc.setSocketOption(SocketConnection.LINGER, 5); InputStream is = sc.openInputStream(); OutputStream os = sc.openOutputStream(); os.write("rn".getBytes()); int ch = 0; while(ch != -1) { ch = is.read(); } is.close(); os.close(); sc.close(); |
下图是我在运行WTK中NetworkDemo的时候的截图!代码也一并发表出来。
package socket; import javax.microedition.midlet.*; import javax.microedition.io.*; import javax.microedition.lcdui.*; import java.io.*; public class SocketMIDlet extends MIDlet implements CommandListener { private static final String SERVER = "Server"; private static final String CLIENT = "Client"; private static final String[] names = { SERVER, CLIENT }; private static Display display; private Form f; private ChoiceGroup cg; private boolean isPaused; private Server server; private Client client; private Command exitCommand = new Command("Exit", Command.EXIT, 1); private Command startCommand = new Command("Start", Command.ITEM, 1); public SocketMIDlet() { display = Display.getDisplay(this); f = new Form("Socket Demo"); cg = new ChoiceGroup("Please select peer", Choice.EXCLUSIVE, names,null); f.append(cg); f.addCommand(exitCommand); f.addCommand(startCommand); f.setCommandListener(this); display.setCurrent(f); } public boolean isPaused() { return isPaused; } public void startApp() { isPaused = false; } public void pauseApp() { isPaused = true; } public void destroyApp(boolean unconditional) { if (server != null) if (client != null) } public void commandAction(Command c, Displayable s) { if (c == exitCommand) else if (c == startCommand) { String name = cg.getString(cg.getSelectedIndex()); if (name.equals(SERVER)) { server = new Server(this); server.start(); } else { client = new Client(this); client.start(); } } } } package socket; import javax.microedition.midlet.*; import javax.microedition.io.*; import javax.microedition.lcdui.*; import java.io.*; public class Server implements Runnable, CommandListener { private SocketMIDlet parent; private Display display; private Form f; private StringItem si; private TextField tf; private boolean stop; private Command sendCommand = new Command("Send", Command.ITEM, 1); private Command exitCommand = new Command("Exit", Command.EXIT, 1); InputStream is; OutputStream os; SocketConnection sc; ServerSocketConnection scn; Sender sender; public Server(SocketMIDlet m) { parent = m; display = Display.getDisplay(parent); f = new Form("Socket Server"); si = new StringItem("Status:", " "); tf = new TextField("Send:", "", 30, TextField.ANY); f.append(si); f.append(tf); f.addCommand(exitCommand); f.setCommandListener(this); display.setCurrent(f); } public void start() { Thread t = new Thread(this); t.start(); } public void run() { try { si.setText("Waiting for connection"); scn = (ServerSocketConnection) Connector.open("socket://:5009"); // Wait for a connection. sc = (SocketConnection) scn.acceptAndOpen(); si.setText("Connection accepted"); is = sc.openInputStream(); os = sc.openOutputStream(); sender = new Sender(os); // Allow sending of messages only after Sender is created f.addCommand(sendCommand); while (true) { StringBuffer sb = new StringBuffer(); int c = 0; while (((c = is.read()) != 'n') && (c != -1)) { sb.append((char) c); } if (c == -1) si.setText("Message received - " + sb.toString()); } stop(); si.setText("Connection is closed"); f.removeCommand(sendCommand); } catch (IOException ioe) { if (ioe.getMessage().equals("ServerSocket Open")) { Alert a = new Alert("Server", "Port 5000 is already taken.",null, AlertType.ERROR); a.setTimeout(Alert.FOREVER); a.setCommandListener(this); display.setCurrent(a); } else { if (!stop) } } catch (Exception e) } public void commandAction(Command c, Displayable s) { if (c == sendCommand && !parent.isPaused()) if ((c == Alert.DISMISS_COMMAND) || (c == exitCommand)) } /** * Close all open streams */ public void stop() { try { stop = true; if (is != null) if (os != null) if (sc != null) if (scn != null) } catch (IOException ioe) } } package socket; import javax.microedition.midlet.*; import javax.microedition.io.*; import javax.microedition.lcdui.*; import java.io.*; public class Client implements Runnable, CommandListener { private SocketMIDlet parent; private Display display; private Form f; private StringItem si; private TextField tf; private boolean stop; private Command sendCommand = new Command("Send", Command.ITEM, 1); private Command exitCommand = new Command("Exit", Command.EXIT, 1); InputStream is; OutputStream os; SocketConnection sc; Sender sender; public Client(SocketMIDlet m) { parent = m; display = Display.getDisplay(parent); f = new Form("Socket Client"); si = new StringItem("Status:", " "); tf = new TextField("Send:", "", 30, TextField.ANY); f.append(si); f.append(tf); f.addCommand(exitCommand); f.addCommand(sendCommand); f.setCommandListener(this); display.setCurrent(f); } /** * Start the client thread */ public void start() { Thread t = new Thread(this); t.start(); } public void run() { try { sc = (SocketConnection) Connector.open("socket://localhost:5009"); si.setText("Connected to server"); is = sc.openInputStream(); os = sc.openOutputStream(); // Start the thread for sending messages - see Sender's main // comment for explanation sender = new Sender(os); // Loop forever, receiving data while (true) { StringBuffer sb = new StringBuffer(); int c = 0; while (((c = is.read()) != 'n') && (c != -1)) { sb.append((char) c); } if (c == -1) // Display message to user si.setText("Message received - " + sb.toString()); } stop(); si.setText("Connection closed"); f.removeCommand(sendCommand); } catch (ConnectionNotFoundException cnfe) { Alert a = new Alert("Client", "Please run Server MIDlet first",null, AlertType.ERROR); a.setTimeout(Alert.FOREVER); a.setCommandListener(this); display.setCurrent(a); } catch (IOException ioe) { if (!stop) } catch (Exception e) } public void commandAction(Command c, Displayable s) { if (c == sendCommand && !parent.isPaused()) if ((c == Alert.DISMISS_COMMAND) || (c == exitCommand)) } /** * Close all open streams */ public void stop() { try { stop = true; if (sender != null) if (is != null) if (os != null) if (sc != null) } catch (IOException ioe) } } package socket; import javax.microedition.midlet.*; import javax.microedition.io.*; import javax.microedition.lcdui.*; import java.io.*; public class Sender extends Thread { private OutputStream os; private String message; public Sender(OutputStream os) { this.os = os; start(); } public synchronized void send(String msg) { message = msg; notify(); } public synchronized void run() { while (true) { // If no client to deal, wait until one connects if (message == null) { try catch (InterruptedException e) } if (message == null) try catch (IOException ioe) // Completed client handling, return handler to pool and // mark for wait message = null; } } public synchronized void stop() { message = null; notify(); } } |
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