如何提供用户名/密码以使用Matlab urlread/urlwrite访问web资源？

Question

在this question之后，关于使用Matlab访问网页上的PDF，它最初是隐藏在Javascript函数后面的。我现在有了一个URL，它允许我直接访问页面，使用Matlab webrowser对象( PDF出现在屏幕上)可以正常工作，但为了保存PDF供后续处理，我似乎需要使用Matlab urlread/urlwrite函数。但是，这些函数不提供提供身份验证凭据的方法。

如何为Matlab的urlread/urlwrite函数提供用户名/密码？

Answer 1

Matlab的urlread()函数有一个"params“参数，但这些参数都是CGI样式的参数，会在URL中进行编码。身份验证使用较低级别的HTTP请求参数完成。Urlread不支持它们，但是您可以直接针对Java URL类编写代码来使用它们。

您还可以使用Sun的sun.misc.BASE64Encoder类以编程方式进行Base64编码。这是一个非标准类，不是标准Java库的一部分，但是您知道Matlab附带的JVM将包含它，因此您可以不用编写它。

这里有一个简单的技巧，展示了它的实际应用。

function [s,info] = urlread_auth(url, user, password)
%URLREAD_AUTH Like URLREAD, with basic authentication
%
% [s,info] = urlread_auth(url, user, password)
%
% Returns bytes. Convert to char if you're retrieving text.
%
% Examples:
% sampleUrl = 'http://browserspy.dk/password-ok.php';
% [s,info] = urlread_auth(sampleUrl, 'test', 'test');
% txt = char(s)

% Matlab's urlread() doesn't do HTTP Request params, so work directly with Java
jUrl = java.net.URL(url);
conn = jUrl.openConnection();
conn.setRequestProperty('Authorization', ['Basic ' base64encode([user ':' password])]);
conn.connect();
info.status = conn.getResponseCode();
info.errMsg = char(readstream(conn.getErrorStream()));
s = readstream(conn.getInputStream());

function out = base64encode(str)
% Uses Sun-specific class, but we know that is the JVM Matlab ships with
encoder = sun.misc.BASE64Encoder();
out = char(encoder.encode(java.lang.String(str).getBytes()));

%%
function out = readstream(inStream)
%READSTREAM Read all bytes from stream to uint8
try
    import com.mathworks.mlwidgets.io.InterruptibleStreamCopier;
    byteStream = java.io.ByteArrayOutputStream();
    isc = InterruptibleStreamCopier.getInterruptibleStreamCopier();
    isc.copyStream(inStream, byteStream);
    inStream.close();
    byteStream.close();
    out = typecast(byteStream.toByteArray', 'uint8'); %'
catch err
    out = []; %HACK: quash
end

Answer 2

作为对此的更新:另一个选项是新函数webread，您可以明确地提供用于基本身份验证的用户名和密码。

options = weboptions('Username','user','Password','your password');
data = webread(url, options);

这也可以用于websave或webwrite。有关weboptions here的更多信息

Answer 3

urlwrite_auth是下一步，所以这里是...

function  [output,status]=urlwrite_auth(url, user, password,location,wanted) 
%URLWRITE_AUTH Like URLWRITE, with basic authentication 
% 
% location is where you want the file saved
% wanted is the name of the file you want
% Returns the output file which is now saved to location. 
% 
% Examples: 
% sampleUrl = 'http://browserspy.dk/password-ok.php'; 
% [output,status] = urlwrite_auth(sampleUrl, 'user', 'password', location, wanted); 


% Matlab's urlread() doesn't do HTTP Request params, so work directly with Java 
jUrl = java.net.URL(url); 
conn = jUrl.openConnection(); 
conn.setRequestProperty('Authorization', ['Basic ' base64encode([user ':' password])]); 
conn.connect()
%note this calls the function below

% Specify the full path to the file so that getAbsolutePath will work when the
% current directory is not the startup directory and urlwrite is given a
% relative path.
file = java.io.File(location);

% the path.
try
    file = file.getCanonicalFile;
catch
    error('MATLAB:urlwrite:InvalidOutputLocation','Could not resolve file    "%s".',char(file.getAbsolutePath));
end

% Open the output file.
pathy=strcat(location,'\',wanted);
try
    fileOutputStream = java.io.FileOutputStream(pathy);
catch
    error('MATLAB:urlwrite:InvalidOutputLocation','Could not open output file "%s".',char(file.getAbsolutePath));
end

% Read the data from the connection.
try
    inputStream = conn.getInputStream;
        import com.mathworks.mlwidgets.io.InterruptibleStreamCopier; 
    % This StreamCopier is unsupported and may change at any time.
    isc = InterruptibleStreamCopier.getInterruptibleStreamCopier;   
    isc.copyStream(inputStream,fileOutputStream);
    inputStream.close;
    fileOutputStream.close;
    output = char(file.getAbsolutePath);
catch
    fileOutputStream.close;
    delete(file);
    if catchErrors, return
    else error('MATLAB:urlwrite:ConnectionFailed','Error downloading URL. Your network     connection may be down or your proxy settings improperly configured.');
    end
end

status = 1;


function out = base64encode(str) 
% Uses Sun-specific class, but we know that is the JVM Matlab ships with 
encoder = sun.misc.BASE64Encoder(); 
out = char(encoder.encode(java.lang.String(str).getBytes())); 
%this is the bit of code that makes it connect!!!!

请注意，这是由Andrew开发的从http用户名和密码站点下载文件的答案。