Shockwave預載技術（二）
為了讓程序擁有更強的適應性，我們還可以添加一個netDone()命令用來檢測網絡錯誤。“Preloader”劇本的下一個版本能夠檢測任何網絡錯誤。一旦發生錯誤，則使用一個參數返回錯誤的描述信息；如果沒有錯誤，那么此參數的取值為一個空字符串。
"Preloader" Parent Script (v.3)
property myNetID, myCallBackObj, myCompletionMsg
on new (me, netAddress, CallBackObj, CompletionMsg)
myCallBackObj = CallBackObj
myCompletionMsg = CompletionMsg
myNetID = preloadNetThing(netAddress)
aTimerObj = timeout(me.string).new(100, #Timer_CheckProgress, me)
end
on Timer_CheckProgress (me, aTimer)
finished = netDone(myNetID)
if finished then
errorNotification = ""
errorNum = netError(myNetID)
if integerP(errorNum) then
if errorNum then
errorNotification = me._GetError(errorNum)
end if
end if
aTimer.forget()
call(myCompletionMsg, myCallBackObj, errorNotification)
else
put "Still downloading"
end if
end
on _GetError (me, errorCode)
case errorCode of
"OK", "", 0: return EMPTY
4: ErrorMsg =( "Bad MOA class. The required Xtras are missing. ")
5: ErrorMsg =( "The required Xtras are improperly installed or not installed at all.")
6: ErrorMsg =( "Bad URL or the required Xtras are improperly installed. ")
20: ErrorMsg =( "Internal error. The browser detected a network or internal error.")
4146: ErrorMsg =( "Connection could not be established with the remote host.")
4149: ErrorMsg =( "Data supplied by the server was in an unexpected format.")
4150: ErrorMsg =( "Unexpected early closing of connection.")
4154: ErrorMsg =( "Operation could not be completed due to timeout.")
4155: ErrorMsg =( "Not enough memory available to complete the transaction.")
4156: ErrorMsg =( "Protocol reply to request indicates an error in the reply.")
4157: ErrorMsg =( "Transaction failed to be authenticated.")
4159: ErrorMsg =( "Invalid URL.")
4164: ErrorMsg =( "Could not create a socket.")
4165: ErrorMsg =( "Requested object could not be found (URL may be incorrect).")
4166: ErrorMsg =( "Generic proxy failure.")
4167: ErrorMsg =( "Transfer was intentionally interrupted by client.")
4242: ErrorMsg =( "Download stopped by netAbort(url).")
4836: ErrorMsg =( "Download stopped for an unknown reason, possibly a network error, or the download was abandoned.")
otherwise
ErrorMsg =("Unknown error code")
end case
return ErrorMsg
end
要想看到具體返回了什么參數，可以像下面這樣修改“PreloaderInterface”行為：
on beginSprite me
clearcache()
urlToLoad = "http://www.lingoworkshop.com/Tutorials/Preloader/Main.dcr"
script("Preloader").new(urlToLoad, me, #mHandlePreloadCompletion)
end
on mHandlePreloadCompletion (me, errorMsg)
if errorMsg <> EMPTY then alert "Network Error!" & return & errorMsg
else alert "All Done"
end
現在，”Preloader”劇本已經有能力預載一個URL並在預載完成時對另一個對象進行返回調用。最后一步則是讓“Preloader”劇本可以報告其運行狀態，以便我們制作一個進度條來給用戶提供一些反饋信息。為了達到這一目的，我們可以使用getStreamStatus(myNetID)函數獲取網絡操作的當前狀態。這個函數會返回一個屬性列表，其中包含像#state（可能是“connecting”或“in progress”）、字節總數和當前已傳遞字節數這樣的信息。在“Preloader”劇本的最終版本中，這些信息被用來確定URL已被下載的部分。此版本附加了一個起始參數“StatusMsg”——返回調用目標用於顯示當前網絡狀況的程序名稱。
"Preloader" Parent Script (v.4)
property myNetID, myCallBackObj, myCompletionMsg, myStatusMessage
on new (me, netAddress, CallBackObj, CompletionMsg, StatusMsg)
myCallBackObj = CallBackObj
myCompletionMsg = CompletionMsg
myStatusMessage = Statusmsg
myNetID = preloadNetThing(netAddress)
aTimerObj = timeout(me.string).new(100, #Timer_CheckProgress, me)
end
on Timer_CheckProgress (me, aTimer)
finished = netDone(myNetID)
if finished then
errorNotification = ""
errorNum = netError(myNetID)
if integerP(errorNum) then
if errorNum then
errorNotification = me._GetError(errorNum)
end if
end if
aTimer.forget()
call(myCompletionMsg, myCallBackObj, errorNotification)
else
-- 仍在預載；檢測是否需要報告當前狀態
if myStatusMessage.ilk = #Symbol then
-- 已經得到一個返回調用消息；獲取狀態列表並將其發送給返回調用目標
theStatus = getStreamStatus(myNetID)
currentState = theStatus.state
-- 在發送狀態列表前計算出已下載部分（變量“fractionDone”）
case (currentState) of
"InProgress":
if theStatus.bytesSoFar > 0 then
if theStatus.bytesTotal > 0 then fractionDone = MIN(1.0, float(theStatus.bytesSoFar) / theStatus.bytesTotal )
else fractionDone = 50
else
fractionDone = 0
end if
"Complete":
fractionDone = 100
otherwise
fractionDone = 0
end case
-- 將fractionDone作為一個屬性添加到狀態列表中
theStatus.addProp( #fractiondone, fractionDone )
-- 通知當前狀態的返回調用對象和已傳遞的百分比
call(myStatusMessage, [myCallbackObj], theStatus)
end if
end if
end
on _GetError (me, errorCode)
case errorCode of
"OK", "", 0: return EMPTY
4: ErrorMsg =( "Bad MOA class. The required Xtras are missing. ")
5: ErrorMsg =( "The required Xtras are improperly installed or not installed at all.")
6: ErrorMsg =( "Bad URL or the required Xtras are improperly installed. ")
20: ErrorMsg =( "Internal error. The browser detected a network or internal error.")
4146: ErrorMsg =( "Connection could not be established with the remote host.")
4149: ErrorMsg =( "Data supplied by the server was in an unexpected format.")
4150: ErrorMsg =( "Unexpected early closing of connection.")
4154: ErrorMsg =( "Operation could not be completed due to timeout.")
4155: ErrorMsg =( "Not enough memory available to complete the transaction.")
4156: ErrorMsg =( "Protocol reply to request indicates an error in the reply.")
4157: ErrorMsg =( "Transaction failed to be authenticated.")
4159: ErrorMsg =( "Invalid URL.")
4164: ErrorMsg =( "Could not create a socket.")
4165: ErrorMsg =( "Requested object could not be found (URL may be incorrect).")
4166: ErrorMsg =( "Generic proxy failure.")
4167: ErrorMsg =( "Transfer was intentionally interrupted by client.")
4242: ErrorMsg =( "Download stopped by netAbort(url).")
4836: ErrorMsg =( "Download stopped for an unknown reason, possibly a network error, or the download was
abandoned.")
otherwise
ErrorMsg =("Unknown error code")
end case
return ErrorMsg
end
"Preloader" Parent Script (v.3)
property myNetID, myCallBackObj, myCompletionMsg
on new (me, netAddress, CallBackObj, CompletionMsg)
myCallBackObj = CallBackObj
myCompletionMsg = CompletionMsg
myNetID = preloadNetThing(netAddress)
aTimerObj = timeout(me.string).new(100, #Timer_CheckProgress, me)
end
on Timer_CheckProgress (me, aTimer)
finished = netDone(myNetID)
if finished then
errorNotification = ""
errorNum = netError(myNetID)
if integerP(errorNum) then
if errorNum then
errorNotification = me._GetError(errorNum)
end if
end if
aTimer.forget()
call(myCompletionMsg, myCallBackObj, errorNotification)
else
put "Still downloading"
end if
end
on _GetError (me, errorCode)
case errorCode of
"OK", "", 0: return EMPTY
4: ErrorMsg =( "Bad MOA class. The required Xtras are missing. ")
5: ErrorMsg =( "The required Xtras are improperly installed or not installed at all.")
6: ErrorMsg =( "Bad URL or the required Xtras are improperly installed. ")
20: ErrorMsg =( "Internal error. The browser detected a network or internal error.")
4146: ErrorMsg =( "Connection could not be established with the remote host.")
4149: ErrorMsg =( "Data supplied by the server was in an unexpected format.")
4150: ErrorMsg =( "Unexpected early closing of connection.")
4154: ErrorMsg =( "Operation could not be completed due to timeout.")
4155: ErrorMsg =( "Not enough memory available to complete the transaction.")
4156: ErrorMsg =( "Protocol reply to request indicates an error in the reply.")
4157: ErrorMsg =( "Transaction failed to be authenticated.")
4159: ErrorMsg =( "Invalid URL.")
4164: ErrorMsg =( "Could not create a socket.")
4165: ErrorMsg =( "Requested object could not be found (URL may be incorrect).")
4166: ErrorMsg =( "Generic proxy failure.")
4167: ErrorMsg =( "Transfer was intentionally interrupted by client.")
4242: ErrorMsg =( "Download stopped by netAbort(url).")
4836: ErrorMsg =( "Download stopped for an unknown reason, possibly a network error, or the download was abandoned.")
otherwise
ErrorMsg =("Unknown error code")
end case
return ErrorMsg
end
要想看到具體返回了什么參數，可以像下面這樣修改“PreloaderInterface”行為：
on beginSprite me
clearcache()
urlToLoad = "http://www.lingoworkshop.com/Tutorials/Preloader/Main.dcr"
script("Preloader").new(urlToLoad, me, #mHandlePreloadCompletion)
end
on mHandlePreloadCompletion (me, errorMsg)
if errorMsg <> EMPTY then alert "Network Error!" & return & errorMsg
else alert "All Done"
end
現在，”Preloader”劇本已經有能力預載一個URL並在預載完成時對另一個對象進行返回調用。最后一步則是讓“Preloader”劇本可以報告其運行狀態，以便我們制作一個進度條來給用戶提供一些反饋信息。為了達到這一目的，我們可以使用getStreamStatus(myNetID)函數獲取網絡操作的當前狀態。這個函數會返回一個屬性列表，其中包含像#state（可能是“connecting”或“in progress”）、字節總數和當前已傳遞字節數這樣的信息。在“Preloader”劇本的最終版本中，這些信息被用來確定URL已被下載的部分。此版本附加了一個起始參數“StatusMsg”——返回調用目標用於顯示當前網絡狀況的程序名稱。
"Preloader" Parent Script (v.4)
property myNetID, myCallBackObj, myCompletionMsg, myStatusMessage
on new (me, netAddress, CallBackObj, CompletionMsg, StatusMsg)
myCallBackObj = CallBackObj
myCompletionMsg = CompletionMsg
myStatusMessage = Statusmsg
myNetID = preloadNetThing(netAddress)
aTimerObj = timeout(me.string).new(100, #Timer_CheckProgress, me)
end
on Timer_CheckProgress (me, aTimer)
finished = netDone(myNetID)
if finished then
errorNotification = ""
errorNum = netError(myNetID)
if integerP(errorNum) then
if errorNum then
errorNotification = me._GetError(errorNum)
end if
end if
aTimer.forget()
call(myCompletionMsg, myCallBackObj, errorNotification)
else
-- 仍在預載；檢測是否需要報告當前狀態
if myStatusMessage.ilk = #Symbol then
-- 已經得到一個返回調用消息；獲取狀態列表並將其發送給返回調用目標
theStatus = getStreamStatus(myNetID)
currentState = theStatus.state
-- 在發送狀態列表前計算出已下載部分（變量“fractionDone”）
case (currentState) of
"InProgress":
if theStatus.bytesSoFar > 0 then
if theStatus.bytesTotal > 0 then fractionDone = MIN(1.0, float(theStatus.bytesSoFar) / theStatus.bytesTotal )
else fractionDone = 50
else
fractionDone = 0
end if
"Complete":
fractionDone = 100
otherwise
fractionDone = 0
end case
-- 將fractionDone作為一個屬性添加到狀態列表中
theStatus.addProp( #fractiondone, fractionDone )
-- 通知當前狀態的返回調用對象和已傳遞的百分比
call(myStatusMessage, [myCallbackObj], theStatus)
end if
end if
end
on _GetError (me, errorCode)
case errorCode of
"OK", "", 0: return EMPTY
4: ErrorMsg =( "Bad MOA class. The required Xtras are missing. ")
5: ErrorMsg =( "The required Xtras are improperly installed or not installed at all.")
6: ErrorMsg =( "Bad URL or the required Xtras are improperly installed. ")
20: ErrorMsg =( "Internal error. The browser detected a network or internal error.")
4146: ErrorMsg =( "Connection could not be established with the remote host.")
4149: ErrorMsg =( "Data supplied by the server was in an unexpected format.")
4150: ErrorMsg =( "Unexpected early closing of connection.")
4154: ErrorMsg =( "Operation could not be completed due to timeout.")
4155: ErrorMsg =( "Not enough memory available to complete the transaction.")
4156: ErrorMsg =( "Protocol reply to request indicates an error in the reply.")
4157: ErrorMsg =( "Transaction failed to be authenticated.")
4159: ErrorMsg =( "Invalid URL.")
4164: ErrorMsg =( "Could not create a socket.")
4165: ErrorMsg =( "Requested object could not be found (URL may be incorrect).")
4166: ErrorMsg =( "Generic proxy failure.")
4167: ErrorMsg =( "Transfer was intentionally interrupted by client.")
4242: ErrorMsg =( "Download stopped by netAbort(url).")
4836: ErrorMsg =( "Download stopped for an unknown reason, possibly a network error, or the download was
abandoned.")
otherwise
ErrorMsg =("Unknown error code")
end case
return ErrorMsg
end
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