 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Java Forum / General / January 2008Reading files from website
I tried to read files (gif) off of various websites, and I got a security error each time. I can easily copy them by hand to my computer. Does Java not have the ability to copy or read files from the internet? >I tried to read files (gif) off of various websites, The internet is a big place. Care to name one specific site/URL that fails for you? >..and I got a >security error each time. I can easily copy them by hand to my >computer. Does Java not have the ability to copy or read files from >the internet? Sure it can. 'Image Fader JApplet'* is an app. that reads files from its own web site, and two others (including mine). * <http://www.knutejohnson.com/>  SignatureAndrew Thompson http://www.physci.org/ > I tried to read files (gif) off of various websites, and I got a > security error each time. Then you must be using a security manager that doesn't allow that. Are your code running as an applet? > I can easily copy them by hand to my computer. Does Java not have > the ability to copy or read files from the internet? Default Java, just running from the command line, can do pretty much anything. You must either be running in a restricted environment or manually set up a security manager to cause security exceptions. /L SignatureLasse Reichstein Nielsen - lrn@hotpop.com DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html> 'Faith without judgement merely degrades the spirit divine.' On Mon, 31 Dec 2007 06:52:47 -0800 (PST), OldPro <rrosskopf@sbcglobal.net> wrote, quoted or indirectly quoted someone who said : >I tried to read files (gif) off of various websites, and I got a >security error each time. I can easily copy them by hand to my >computer. Does Java not have the ability to copy or read files from >the internet? Use the Download utility part of http://mindprod.com/products1.html#FILETRANSFER SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com > On Mon, 31 Dec 2007 06:52:47 -0800 (PST), OldPro > <rrosskopf@sbcglobal.net> wrote, quoted or indirectly quoted someone [quoted text clipped - 7 lines] > Use the Download utility part of > http://mindprod.com/products1.html#FILETRANSFER Or use the wget utility. Its been ported to most OSes. Signaturemartin@ | Martin Gregorie gregorie. | Essex, UK org | >> On Mon, 31 Dec 2007 06:52:47 -0800 (PST), OldPro >> <rrosskopf@sbcglobal.net> wrote, quoted or indirectly quoted someone >> who said : >>> I tried to read files (gif) off of various websites, and I got a >>> security error each time. Maybe I missed some context, but if you get security errors, doesn't that mean that your jvm is not trusting the class-file that tries to download stuff. Is it an unsigned applet from a webpage? > Or use the wget utility. Its been ported to most OSes. If the applet(?) is denied access to foreign servers, it will most likely be also denied permission to start external programs, locally. >> Or use the wget utility. Its been ported to most OSes. > > If the applet(?) is denied access to foreign servers, it will > most likely be also denied permission to start external programs, > locally. The OP isn't using an applet. I just reviewed the thread to be certain. He just asked why his (Java) program couldn't download some GIF images from various websites. wget can in general read anything that a browser can display, unless its prevented by the content of a robots.txt file. OK, its got a shed-load of options, but writing a script that uses it to go get some image files has to be a lot quicker than writing a Java program to do the same job even if you use the web access classes. That's why I suggested using it. Signaturemartin@ | Martin Gregorie gregorie. | Essex, UK org | > wget can in general read anything that a browser can display, unless > its prevented by the content of a robots.txt file. Wget can and will retrieve any document specifically requested, regardless of robots.txt. However it *chooses* to obey robots.txt when recursively retrieving large parts of websites (with "wget -r"). /gordon -- On Mon, 31 Dec 2007 06:52:47 -0800 (PST), OldPro <rrosskopf@sbcglobal.net> wrote, quoted or indirectly quoted someone who said : >I tried to read files (gif) off of various websites, and I got a >security error each time. I can easily copy them by hand to my >computer. Does Java not have the ability to copy or read files from >the internet? see http://mindprod.com/jgloss/applet.html Applets are not permitted to read from any server other than the one they were loaded from unless they are signed. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com > On Mon, 31 Dec 2007 06:52:47 -0800 (PST), OldPro > <rrosskopf@sbcglobal.net> wrote, quoted or indirectly quoted someone [quoted text clipped - 9 lines] > Applets are not permitted to read from any server other than the one > they were loaded from unless they are signed. The OP didn't mention applets. He also doesn't say whether he's using the web-related standard classes but if he is, could he be getting blocked by robots.txt? I had a quick scan of documentation for likely classes but couldn't find anything that says whether robots.txt is honored or ignored. Signaturemartin@ | Martin Gregorie gregorie. | Essex, UK org | > The OP didn't mention applets. He also doesn't say whether he's > using the web-related standard classes but if he is, could he be > getting blocked by robots.txt? I had a quick scan of documentation > for likely classes but couldn't find anything that says whether > robots.txt is honored or ignored. I can't imagine why the web-related standard classes should silently read and obey robots.txt on behalf of every possible client application that uses them. Certainly not every java program is a web crawler, and anyway robots.txt is just advisory. /gordon -- >> The OP didn't mention applets. He also doesn't say whether he's >> using the web-related standard classes but if he is, could he be [quoted text clipped - 6 lines] > application that uses them. Certainly not every java program is a web > crawler, and anyway robots.txt is just advisory. I think you're right. I just wanted to highlight the point that you can build web crawlers with these classes in java.net and that many of these classes are among the worst documented standard classes. There is no java.net class I'm aware of that accesses or implements robots.txt but if there was one it would need to be woven into this package or applying the rules in this file could be, um, interesting. I notice that the OP has been silent since his initial post. I for one don't intend to say anything more unless/until he posts again with more details or results. Signaturemartin@ | Martin Gregorie gregorie. | Essex, UK org | Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.