Blackberry主推推送技術，但何爲推送技術，客戶端對推送技術是怎樣支持的？
推送的過程有應用服務發起，由BES服務器執行，數據通過BB專線，無線網最終達到黑莓手機終端，數據推送的目標終端以email地址或PIN決定。BES服務器與應用服務器或email服務器之間有輪詢交互，BES服務器輪循應用服務器查看數據更新，如有更新，應用服務器會發起推送請求。
對於客戶端應用來說，不存在輪循的操作。客戶端應用只需偵聽指定的端口，當數據到達時，客戶端應用會被通知來處理到達的數據。以下是客戶端實現偵聽的範例代碼：
class ListenerThread extends Thread {
LISTEN_URL = "http://:911";
public void run() {
StreamConnectionNotifier notify = null;
StreamConnection stream = null;
InputStream input = null;
try{//wait for the device to load
sleep(1000);
}
catch(Exception e){}
for(;;) {//in case an exception is thrown, re try to get the data
try {
notify = (StreamConnectionNotifier)Connector.open(LISTEN_URL);
for(;;){
//NOTE: the following will block until data is received
stream = notify.acceptAndOpen();
input = stream.openInputStream();
//Extract the data from the input stream
StringBuffer sb = new StringBuffer();
int datum = -1;
while ( -1 != (datum = input.read()) )
{
sb.append((char)datum);
}
stream.close();
stream = null;
String contactData = sb.toString();
DataStore dataStore = new DataStore();
dataStore.saveData(contactData);
System.err.println("Push message received...("+contactData.length()+" bytes)/n");
System.err.println(contactData);
//triggering a notification event since data has been received
NotificationsManager.triggerImmediateEvent(ID_1,0,this,null);//notifing the device of new content being received
}
}
catch (IOException e){
//likely the stream was closed
System.err.println(e.toString());
}
finally {
try {
if (stream != null){
stream.close();
}
}
catch (Exception ex){}
try{
if (notify != null){
notify.close();
}
}
catch (Exception ex){}
}//end finally
}//end for
}//end run
}//end listenerthread
}//end pushdatalistener
