We have summarized the settings for downloading files on the Web system by linking Tomcat and Apache. [Confirmed environment]
response.setContentType("application/octet-stream");
response.getWriter().write("Hello World");
https://developer.mozilla.org/ja/docs/Web/HTTP/Basics_of_HTTP/MIME_types
This is the default value for binary format files. It actually represents an unknown binary format file, and the browser usually does not run it automatically or ask if it should run. They treat the value of the Content-Disposition header as if it were an attachment and suggest that the file be'save as'.
As mentioned above, you can download it by specifying ʻapplication / octet-stream as the content type. However, if you know the type of file to download, it feels strange to specify ʻapplication / octet-stream.
As shown below, if you specify ʻattachment` in the Content-Disposition header, you can download even if the content type is not" application / octet-stream ".
response.setContentType("text/html");
response.setHeader("Content-Disposition","attachment");
response.getWriter().write("Hello World");
The value specified for filename will be the default file name at the time of download.
response.setHeader("Content-Disposition","attachment;filename=\"sample.html\"");
// attachment;filename="sample.html"
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition
When used in combination with Content-Disposition: attachment, it is used as the default filename for an eventual 'Save As" dialog presented to the user.
If the file name contains double-byte characters, use filename *.
String encodedFilename = URLEncoder.encode("sample.html", "UTF-8");
response.setHeader("Content-Disposition","attachment;filename*=\"UTF-8''" + encodedFilename + "\"");
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition
The parameters "filename" and "filename*" differ only in that "filename*" uses the encoding defined in RFC 5987. When both "filename" and "filename*" are present in a single header field value, "filename*" is preferred over "filename" when both are present and understood.
Please note that half-width whitespace characters are converted to the plus sign "+". The code below will have the file name ʻa + b.html`.
String encodedFilename = URLEncoder.encode("a b.html", "UTF-8");
response.setHeader("Content-Disposition","attachment;filename*=\"UTF-8''" + encodedFilename + "\"");
This is a Java URL Encoder specification. https://docs.oracle.com/javase/jp/8/docs/api/java/net/URLEncoder.html
The whitespace character "" is converted to the plus sign "+".
If you replace the "+" with % 20, a whitespace character will appear in the file name.
By the way, URLEncode has dialects depending on the language, so I will not go into it. .. ..
https://www.glamenv-septzen.net/view/1170
Characters that cannot be used in the file name are converted to underscores.
The code below will have the file name _________.html.
// ¥ / : * ? " < > |File name including
String encodedFilename = URLEncoder.encode("\\/:*\"<>|.html", "UTF-8");
response.setHeader("Content-Disposition","attachment;filename*=\"UTF-8''" + encodedFilename + "\"");
filename andfilename *If you write both filename andfilename *as shown below, filename will be ignored if filename * is valid.
If you consider browsers that do not support filename * (is there such a browser in 2017?), It seems good to write them together.
String encodedFilename = URLEncoder.encode("sample.html", "UTF-8");
response.setHeader("Content-Disposition","attachment;" +
"filename=\"sample.html\"" +
"filename*=\"UTF-8''" + encodedFilename + "\"");
Therefore, when both "filename" and "filename*" are present in a single header field value, recipients SHOULD pick "filename*" and ignore "filename".
filaname *In the RFC 6266 example, filename has double quotes, butfilename *does not.
Content-Disposition: attachment;
filename="EURO rates";
filename*=utf-8''%e2%82%ac%20rates
If you put double quotes in filename * (filename * =" utf-8''sample.html "), the download result of each browser is as follows.
Other than Firefox, filename * was ignored and the filename was "download".
Enable mod_headers and specify the Content-disposition header. The following code will download all xml files under Apache.
LoadModule headers_module modules/mod_headers.so
<FilesMatch "\.(xml)$">
Header set Content-Disposition attachment
</FilesMatch>
[Reference site] http://qiita.com/kompiro/items/ac60721bc43625a057dc
If you access http://sample.co.jp/sample.xml, it will be downloaded with the file name" sample.xml ".
Notice that the file name is included in the URL. If the file name contains characters that have a special meaning as the URL, it will not be downloaded correctly. File names containing the following characters were not downloaded correctly. (Check with Firefox. It is unknown whether this is all the characters that cannot be used in the file name)
# %
If the download attribute is specified in the a element, the value specified in the download attribute will be downloaded as the file name. You can also use double-byte characters, single-byte spaces, and #, which has a special meaning as a URL.
However, IE is not supported ...
<a href="sample.png " download="Test a b#%.png ">Download</a>
https://developer.mozilla.org/ja/docs/Web/HTML/Element/a
This attribute tells the browser to download instead of navigating to the URL, prompting the user to save it as a local file. If you specify a value for the attribute, it will be interpreted as the default filename for the save prompt (users can rename it if desired). There is no limit to the values that can be used, but / and \ convert to underscores. Many file systems have restrictions on the characters that can be used in filenames, and the browser may adjust the filenames.
<a href="sample.png " download="Test a b#%.png ">Download</a>
If you specify \ /: *?" <> | In the download attribute, all are converted to underscores (confirmed with Firefox).
The code below will have the file name _________.html.
<a href="sample.png " download="\/:*?"<>|.png ">Download</a>
Prior to Tomcat 7 (?), The default for ʻURIEncoding is ʻISO-8859-1. This character code is a Latin alphabet character set and cannot represent Japanese.
https://tomcat.apache.org/tomcat-7.0-doc/config/http.html#Common_Attributes
This specifies the character encoding used to decode the URI bytes, after %xx decoding the URL. If not specified, ISO-8859-1 will be used.
Therefore, if you want to download a file containing Japanese, you need to set the character code to UTF-8.
server.xml
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443"
URIEncoding="UTF-8" /><!--← Addendum-->
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443"
URIEncoding="UTF-8" /><!--← Addendum-->
In Tomcat8, the default is UTF-8, so you do not need to specify it.
https://tomcat.apache.org/tomcat-8.0-doc/config/http.html#Common_Attributes
This specifies the character encoding used to decode the URI bytes, after %xx decoding the URL. If not specified, UTF-8 will be used unless the org.apache.catalina.STRICT_SERVLET_COMPLIANCE system property is set to true in which case ISO-8859-1 will be used.
[Reference site] http://qiita.com/kazuki43zoo/items/a365d194f5c4df28912f
Recommended Posts