我這天，開發(fā)網(wǎng)絡(luò)連接程序，遇到n多問題，都得以解決。
總結(jié)一下。
首先是環(huán)境。
我用的開發(fā)SDK和模擬器都是Sun的，J2ME Wireless Toolkit 2.2
現(xiàn)在UltraEdit下面寫一個網(wǎng)絡(luò)程序。注意一定要在網(wǎng)絡(luò)連接動作時，另外啟動一下線程，否則模擬器運行會有錯誤。
很不好的代碼：不要使用！！！！！！！！！！
import java.io.InputStream;
import java.io.OutputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.io.StreamConnection;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.AlertType;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.TextBox;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
public class MainMidlet extends MIDlet
implements CommandListener
{
private Display display;
public MainMidlet() {
super();
display = Display.getDisplay(this);
}
private Form f;
private TextField server;
private TextField port;
private TextBox showBox;
protected void startApp() throws MIDletStateChangeException {
f = new Form("Test Network");
server = new TextField("服務(wù)器","www.google.com",20,TextField.ANY);
port = new TextField("端口","80",4,TextField.NUMERIC);
showBox = new TextBox("連接數(shù)據(jù)", "Init",1024,TextField.ANY);
showBox.addCommand(new Command("返回",Command.BACK,1));
showBox.setCommandListener(this);
f.append(server);
f.append(port);
f.addCommand(new Command("Socket連接",Command.SCREEN,1));
f.addCommand(new Command("Http連接",Command.SCREEN,1));
f.setCommandListener(this);
display.setCurrent(f);
}
protected void pauseApp() {
// TODO Auto-generated method stub
}
protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
// TODO Auto-generated method stub
}
public void commandAction(Command arg0, Displayable arg1) {
if(arg0.getLabel().equals("Socket連接"))
{
socketconnect();
}
else if(arg0.getLabel().equals("Http連接"))
{
httpconnect();
}
else if(arg0.getLabel().equals("返回"))
{
display.setCurrent(f);
}
}
private void socketconnect()
{
StreamConnection socket = null;
InputStream is = null;
OutputStream os = null;
try{
String name = "http://" + server.getString() + ":" + port.getString();
socket = (StreamConnection)Connector.open(name,Connector.READ_WRITE);
String request = "GET / HTTP/1.0\n\n";
os = socket.openOutputStream();
os.write(request.getBytes());
is = socket.openInputStream();
final int MAX_LENGTH = 128;
byte[] buf = new byte[MAX_LENGTH];
int total = 0;
while(total < MAX_LENGTH){
int count = is.read(buf,total, MAX_LENGTH - total);
if(count < 0)
{
break;
}
total += count;
}
String toshow = new String(buf,0,buf.length);
showBox.setString(toshow);
display.setCurrent(showBox);
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,f);
}finally{
if(is != null)
{
try{
is.close();
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,f);
}
is = null;
}
if(os != null)
{
try{
os.close();
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,f);
}
os = null;
}
if(socket != null)
{
try{
socket.close();
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,f);
}
socket = null;
}
}
}
private void httpconnect()
{
HttpConnection conn = null;
InputStream is = null;
OutputStream os = null;
try{
String url = "wap.winwap.com";
conn = (HttpConnection)Connector.open("http://10.0.0.172/" + "home.wml");
conn.setRequestProperty("X-Online-Host",url);
conn.setRequestMethod(HttpConnection.GET);
if(conn.getResponseCode() == HttpConnection.HTTP_OK)
{
is = conn.openInputStream();
final int MAX_LENTH = 128;
byte[] buf = new byte[MAX_LENTH];
int total = 0;
while(total < MAX_LENTH)
{
int count = is.read(buf,total,MAX_LENTH - total);
if(count < 0)
break;
total += count;
}
is.close();
String reply = new String(buf,0,total);
showBox.setString(reply);
display.setCurrent(showBox);
}else{
showBox.insert(String.valueOf(conn.getResponseCode()),showBox.getCaretPosition());
showBox.insert(String.valueOf(HttpConnection.HTTP_OK),showBox.getCaretPosition());
display.setCurrent(showBox);
}
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,showBox);
}finally{
if(is != null)
{
try{
is.close();
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,showBox);
}
is = null;
}
if(os != null)
{
try{
os.close();
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,showBox);
}
os = null;
}
if(conn != null)
{
try{
conn.close();
}catch(Exception ex)
{
Alert al = new Alert("未定義異常", ex.getMessage(), null, AlertType.ALARM);
al.setTimeout(Alert.FOREVER);
display.setCurrent(al,showBox);
}
conn = null;
}
}
}
}
這段代碼，在模擬器上運行很有問題！
這以后，再按鈕就沒有反應(yīng)了，而且，會有警告warning
警告: 若要避免潛在的死鎖，應(yīng)該在 commandAction() 處理程序之外的其他線程中執(zhí)行
可能會阻塞的
操作(如網(wǎng)絡(luò)連接)。
模擬器再不能正常鏈接了。無法配置。
===============================================
改代碼如下：
import javax.microedition.io.*;
import java.io.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class QueryForm extends TextBox implements CommandListener
{
MIDlet midlet ;
public QueryForm(MIDlet m)
{
super("請輸入網(wǎng)址","http://wap.winwap.com",40,TextField.ANY) ;
midlet = m ;
addCommand(new Command("離開",Command.SCREEN,1)) ;
addCommand(new Command("查詢",Command.SCREEN,1)) ;
setCommandListener(this) ;
}
public void commandAction(Command c,Displayable s)
{
String cmd = c.getLabel() ;
if(cmd.equals("離開"))
{
midlet.notifyDestroyed() ;
}else if(cmd.equals("查詢"))
{
String url = getString() ; //連接網(wǎng)址
WorkThread wt = new WorkThread(url,Display.getDisplay(midlet)) ;
wt.start() ;
}
}
}
import javax.microedition.io.*;
import java.io.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class MyHttpClient extends MIDlet
{
Display display ;
public MyHttpClient()
{
display = Display.getDisplay(this) ;
}
public void startApp()
{
display.setCurrent(new QueryForm(this));
}
public void pauseApp()
{
}
public void destroyApp(boolean con)
{
}
}
import javax.microedition.io.*;
import java.io.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class WorkThread extends Thread
{
String url ;
Display display ;
public WorkThread(String url,Display d)
{
this.url = url ;
display = d ;
System.out.println("準(zhǔn)備連接："+this.url) ;
}
public void run()
{
HttpConnection conn = null;
InputStream is = null;
InputStreamReader isr = null ;
StringBuffer line = new StringBuffer("");
try {
conn = (HttpConnection)Connector.open(url);
System.out.println("內(nèi)容長度：" + conn.getLength()) ;
is = conn.openInputStream();
isr = new InputStreamReader(is) ;
int ic ;
while( (ic = isr.read()) != -1 )
{
line.append((char)ic) ;
}
}catch (Exception ioe)
{
System.out.println(ioe);
}finally
{
try
{
if(conn!=null)
conn.close();
}catch(Exception e){}
}
Alert al = new Alert("查詢結(jié)果",line.toString(),null,AlertType.CONFIRMATION);
al.setTimeout(Alert.FOREVER) ;
display.setCurrent(al) ;
}
}
可以了，在運行代碼，就會看到模擬同樣出現(xiàn)提示，但是確認(rèn)后，模擬器會走本地的網(wǎng)絡(luò)，鏈接站點。
OK，成功在模擬器上訪問了。
注意，這僅僅是模擬器，部署到手機(jī)上，要對程序稍加改動，才能用。
在中國移動提供的網(wǎng)絡(luò)連接中，分為CMNET和CMWAP兩種，其中CMNET可以無限制的訪問互聯(lián)網(wǎng)絡(luò)，資費比較貴。CMWAP類似一個HTTP的代碼，只能訪問支持HTTP的應(yīng)用，但是資費便宜，穩(wěn)定性比較差。
在實際的J2ME網(wǎng)絡(luò)編程中，一般需要提供以CMWAP代理的方式連接網(wǎng)絡(luò)，在J2ME中，連接的代碼和直接連接有所不同，代碼如下：
HttpConnection http = (HttpConnection)Connector.open(("http://10.0.0.172/"+url);
http.setRequestProperty("X-Online-Host",ServerName);
例如你需要訪問的地址為：http://www.test.com/login/loginServlet則上面的代碼就為：
HttpConnection http = (HttpConnection)Connector.open(("http://10.0.0.172/" + "login/loginServlet");
http.setRequestProperty("X-Online-Host","www.test.com");
在實際使用過程中，只需要使用實際需要訪問的地址的域名或者IP來代替ServerName，例如示例中的“www.test.com”，使用后續(xù)的地址類代替代碼中的url，例如示例中的“l(fā)ogin/loginServlet”，就可以實際的使用CMWAP代理來進(jìn)行連接了。
嗚呼，休息一下，在達(dá)內(nèi)學(xué)習(xí)完C++，最強大的多范型語言，學(xué)習(xí)J2ME只需要一周就足夠了。好比是九陽神功在體內(nèi)，無所不能。阿，哈哈哈。Java乃是乾坤大挪移。