分享
 
 
 

J2ME中使用Socket开发联网程序

王朝java/jsp·作者佚名  2008-05-31
窄屏简体版  字體: |||超大  

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("\r\n".getBytes());

int ch = 0;

while(ch != -1) {

ch = is.read();

}

is.close();

os.close();

sc.close();

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。

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) {

server.stop();

}

if (client != null) {

client.stop();

}

}

public void commandAction(Command c, Displayable s) {

if (c == exitCommand) {

destroyApp(true);

notifyDestroyed();

} 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) {

break;

}

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) {

ioe.printStackTrace();

}

}

} catch (Exception e) {

e.printStackTrace();

}

}

public void commandAction(Command c, Displayable s) {

if (c == sendCommand && !parent.isPaused()) {

sender.send(tf.getString());

}

if ((c == Alert.DISMISS_COMMAND) (c == exitCommand)) {

parent.notifyDestroyed();

parent.destroyApp(true);

}

}

/**

* Close all open streams

*/

public void stop() {

try {

stop = true;

if (is != null) {

is.close();

}

if (os != null) {

os.close();

}

if (sc != null) {

sc.close();

}

if (scn != null) {

scn.close();

}

} 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) {

break;

}

// 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) {

ioe.printStackTrace();

}

} catch (Exception e) {

e.printStackTrace();

}

}

public void commandAction(Command c, Displayable s) {

if (c == sendCommand && !parent.isPaused()) {

sender.send(tf.getString());

}

if ((c == Alert.DISMISS_COMMAND) (c == exitCommand)) {

parent.notifyDestroyed();

parent.destroyApp(true);

}

}

/**

* Close all open streams

*/

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
2023年上半年GDP全球前十五强
 百态   2023-10-24
美众议院议长启动对拜登的弹劾调查
 百态   2023-09-13
上海、济南、武汉等多地出现不明坠落物
 探索   2023-09-06
印度或要将国名改为“巴拉特”
 百态   2023-09-06
男子为女友送行,买票不登机被捕
 百态   2023-08-20
手机地震预警功能怎么开?
 干货   2023-08-06
女子4年卖2套房花700多万做美容:不但没变美脸,面部还出现变形
 百态   2023-08-04
住户一楼被水淹 还冲来8头猪
 百态   2023-07-31
女子体内爬出大量瓜子状活虫
 百态   2023-07-25
地球连续35年收到神秘规律性信号,网友:不要回答!
 探索   2023-07-21
全球镓价格本周大涨27%
 探索   2023-07-09
钱都流向了那些不缺钱的人,苦都留给了能吃苦的人
 探索   2023-07-02
倩女手游刀客魅者强控制(强混乱强眩晕强睡眠)和对应控制抗性的关系
 百态   2020-08-20
美国5月9日最新疫情:美国确诊人数突破131万
 百态   2020-05-09
荷兰政府宣布将集体辞职
 干货   2020-04-30
倩女幽魂手游师徒任务情义春秋猜成语答案逍遥观:鹏程万里
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案神机营:射石饮羽
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案昆仑山:拔刀相助
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案天工阁:鬼斧神工
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案丝路古道:单枪匹马
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案镇郊荒野:与虎谋皮
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案镇郊荒野:李代桃僵
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案镇郊荒野:指鹿为马
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案金陵:小鸟依人
 干货   2019-11-12
倩女幽魂手游师徒任务情义春秋猜成语答案金陵:千金买邻
 干货   2019-11-12
 
推荐阅读
 
 
 
>>返回首頁<<
 
靜靜地坐在廢墟上,四周的荒凉一望無際,忽然覺得,淒涼也很美
© 2005- 王朝網路 版權所有