It’s important to set the Content-Type header to a non-standard value such as application/x-download because, although the HTTP specification provides a mechanism for file downloads, many browsers second-guess the server's directives and do what they think is best rather than what they're told.
These browsers--including Microsoft Internet Explorer and Opera--look at the file extension and "sniff" the incoming content. If they see HTML or image content, they inline-display the file contents instead of offering a Save As dialog. Turns out there are no 100% reliable ways to download a file across all browsers.
According to a reference site, the HTTP specification recommends setting the Content-Type to application/octet-stream. Unfortunately, this causes problems with Opera 6 on Windows (which will display the raw bytes for any file whose extension it doesn't recognize) and on Internet Explorer 5.1 on the Mac (which will display inline content that would be downloaded if sent with an unrecognized type). So, the best way to cater for max scenario case coverage will be to set to application/x-download.
Monday, August 31, 2009
Some Java String & Collections API notes
Some summary of String and Collections API usage to remind myself :)
Criteria to choose among String, StringBuffer and StringBuilder:
1. If your text is not going to change use a string Class because a String object is immutable.
2. If your text can change and will only be accessed from a single thread, use a StringBuilder because StringBuilder is unsynchronized.
3. If your text can changes, and will be accessed from multiple threads, use a StringBuffer because StringBuffer is synchronous.
Collections API:
1. Vectors and Hashtable classes are available from the initial JDK 1.0. But, ArrayList and HashMap are added as a part of new Collections API since JDK 1.2.
2. Vectors and Hashtable are synchronized where as ArrayList and HashMap are unsynchronized.
3. Use Vector if there are multiple threads and ArrayList if there is only a single thread.
4. Use Hashtable if there are multiple threads and HashMap if there is only a single thread.
Criteria to choose among String, StringBuffer and StringBuilder:
1. If your text is not going to change use a string Class because a String object is immutable.
2. If your text can change and will only be accessed from a single thread, use a StringBuilder because StringBuilder is unsynchronized.
3. If your text can changes, and will be accessed from multiple threads, use a StringBuffer because StringBuffer is synchronous.
Collections API:
1. Vectors and Hashtable classes are available from the initial JDK 1.0. But, ArrayList and HashMap are added as a part of new Collections API since JDK 1.2.
2. Vectors and Hashtable are synchronized where as ArrayList and HashMap are unsynchronized.
3. Use Vector if there are multiple threads and ArrayList if there is only a single thread.
4. Use Hashtable if there are multiple threads and HashMap if there is only a single thread.
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