www.gusucode.com > external 工具箱matlab源码程序 > external/interfaces/webservices/http/+matlab/+net/+http/+internal/readContentFromWebService.m
function [data, payloadLength, payload, charset] = readContentFromWebService(arg1, arg2, convert, raw)
%readContentFromWebService Read content from Web service
% [data, payloadLength, payload] = readContentFromWebService(connector, log, convert, raw)
% reads the content from the Web service indicated by connector and returns the
% response in data and payload, and the original payloadLength. If convert is
% set, the response is decoded based on connector.ContentType and returned in data.
% If there is no ContentType, process as application/octet-stream (as per section
% 3.1.1.5 of RFC 7231), which returns a uint8 vector. Caller can do "content
% sniffing" if this is needed.
%
% data = readContentFromWebService(payload, contentType) is the same, but reads and
% converts the payload already in memory using the specified contentType or
% application/octet-stream as above. This form is used to re-convert a
% payload received from the web that was improperly converted or which was
% not converted the first time.
%
% connector - a HTTPConnector object on which a request has been sent and
% response received. Returns empty if the connector has no response
% message or the response has no content. We use connector.ContentType
% to determine the contentType for conversion.
%
% log - call connector.log to log the message containing this data
%
% convert - Used only if raw is false: If true, convert the payload to MATLAB
% data based on contentType and return in data. If false, just
% convert payload to Unicode based on charset in or implied by the
% contentType. If false and there is no charset, return raw
% uint8 vector in data (same as payload).
%
% raw - (optional) If true, just return raw payload and leave data []. In
% this case payload must be specified.
%
% contentType - the MediaType to use to convert the data or []
%
% data - the data, converted based on connector.Content-Type and charset and
% whether convert is specified.
%
% payloadLength - the length of the unconverted payload; useful when payload is not
% being returned.
%
% payload - the unconverted data as a uint8 array.
%
% charset - If convert = false or raw = true, and contentType is character
% data that we are returning in data, this is the charset we
% used to convert the payload. The purpose of this is to
% communicate the charset when we didn't do a full conversion of
% payload based on contentType, but only converted the
% characters to Unicode.
% Copyright 2015-2016 The MathWorks, Inc.
% Convert the ContentType in the received message (e.g. text/plain,
% application/json, etc) to a simple form (e.g. text, image, json, etc.)
useConnector = isa(arg1, 'matlab.net.http.internal.HTTPConnector');
if useConnector
connector = arg1;
log = arg2;
contentType = lower(connector.ContentType);
if isempty(contentType)
mediaType = [];
else
mediaType = matlab.net.http.MediaType(contentType);
end
else
payload = arg1;
mediaType = arg2;
log = false;
end
if nargin < 4
raw = false;
end
if ~raw
if isempty(mediaType)
simpleType = [];
charset = '';
else
simpleType = matlab.net.http.internal.getSimpleType(mediaType);
subtype = lower(mediaType.Subtype);
% this may return '' if no charset can be determined
charset = matlab.net.internal.getCharsetForMediaType(mediaType);
end
else
% expect payload if raw specified
assert(nargout > 1)
end
if ~raw && (~useConnector || convert) && ~isempty(simpleType)
downloadToFile = contentRequiresFileDownload(simpleType);
if downloadToFile
filename = getTempname(simpleType, subtype);
if isempty(filename)
% empty filename means we can't convert it, so just return raw data
downloadToFile = false;
convert = false;
end
end
else
downloadToFile = false;
end
if downloadToFile
% We take this path only when convert = true and we need to write it to a
% file in order to convert it.
cleanup = onCleanup(@()deleteFile(filename));
if useConnector
% This downloads the data from the server into the file
connector.copyContentToFile(filename);
else
% payload was set above in the ~useConnector case
f = fopen(filename, 'w');
cleanf = onCleanup(@()fclose(f));
fwrite(f, payload);
payloadLength = length(payload);
clear cleanf
end
e = [];
try
% Read it back, possibly using charset for simpleType = 'text', using the
% converter based on simpleType and charset. This function assumes we
% don't call it for simpleTypes like 'json' that don't require file
% download.
data = matlab.net.http.internal.readContentFromFile(filename, ...
charset, simpleType, subtype);
if exist('payload','var')
payloadLength = length(payload);
else
% If we were called with a 1st argument of HTTPConnector, the payload was
% written directly to the file, not passed in, so get its length.
info = dir(filename);
payloadLength = info.bytes;
end
catch e
% just save the exception; it's some non-HTTP exception
end
if (~isempty(e) || nargout > 1 || log) && exist(filename,'file')
% if there was an exception, or we need to get the payload for logging,
% and the file was created, then fetch the payload from the file.
f = fopen(filename,'r','n');
clean2 = onCleanup(@()fclose(f));
payload = fread(f,Inf','uint8=>uint8');
payloadLength = length(payload);
clear clean2
end
if ~isempty(e)
% If an exception occurred reading or converting content, throw
% MATLAB:http exception with a special message that includes the message
% in the exception.
if useConnector
me = MException(message('MATLAB:http:CannotConvertContent', ...
char(connector.URI), char(mediaType)));
else
me = MException(message('MATLAB:http:CannotConvertPayload', ...
char(mediaType)));
end
% Add e as the cause just so we can get its stack trace.
% Adding e as the cause here will cause the message to be duplicated when
% getReport is called on me, but this is the only way to get the original
% stack to appear, since we can't directly set me.stack.
me = me.addCause(e);
% Throw an HTTPException that contains a history and a ResponseMessage with
% the payload filled in.
if isempty(charset)
throw(matlab.net.http.internal.ExceptionWithPayload(payload, me));
else
% If there is a charset, then also populate data with the characters. This gives
% us human-readable input in ResponseMessage.Body.Data.
data = string(native2unicode(payload', char(charset)));
throw(matlab.net.http.internal.ExceptionWithPayload(payload, me, data, charset));
end
end
% conversion successful, no charset in this case
charset = [];
else
% convert is false or content can be decoded without file download.
% Copy the raw data stream from the connection to byteArray.
if useConnector
payload = connector.copyContentToByteArray();
url = char(connector.URI);
else
url = [];
end
payloadLength = length(payload);
if raw
data = [];
charset = [];
else
% Decode the byte array. Here, simpleType and charset may be empty.
% This throws ExceptionWithPayload if decoding or conversion failed.
data = matlab.net.http.internal.decodeByteArray(payload, charset, ...
simpleType, url, convert);
if convert || isempty(simpleType)
% if data was converted or there was no simpleType (indicating we're just
% returning the binary data), don't return a charset.
charset = [];
end
end
end
if log
connector.log(data, payload);
end
end
%--------------------------------------------------------------------------
function fname = getTempname(simpleType, subtype)
% Return a temp file name for downloading content. subtype must be string
fname = tempname;
suffix = matlab.net.http.internal.getSuffixForSubtype(simpleType, subtype);
if isempty(suffix)
if ~ischar(suffix)
% suffix of [] indicates we recognize the simpleType but don't know how to
% convert the subtype
fname = [];
end
else
fname = [fname '.' suffix];
end
end
%--------------------------------------------------------------------------
function downloadToFile = contentRequiresFileDownload(simpleType)
% Return true if content requires downloading to a file.
downloadToFile = any(strcmpi(simpleType,{'image','table','xmldom','audio'}));
end
%--------------------------------------------------------------------------
function deleteFile(filename)
% Delete filename, if it exists.
if exist(filename, 'file')
delete(filename)
end
end