MimeType must use case insensitive comparisons for Charsets [SPR-13157]

[spring-projects-issues]

Sam Brannen opened SPR-13157 and commented

Status Quo

Spring's MimeType currently performs exact equality checks for "charset" values in its parameters field -- see org.springframework.util.MimeType.equals(Object).

As a result, the MIME types text/plain;charset=UTF-8 and text/plain;charset=utf-8 are incorrectly considered to be different, and this breaks the contract for Java's Charset:

Charset names are not case-sensitive; that is, case is always ignored when comparing charset names.

See also: failing build SPR-PUB-2539.

Related Resources

• Change in Jetty 9 that is related to charsets.

---

Affects: 4.0 GA

Issue Links:

• MimeType compareTo implementation is not compatible with equals [SPR-16458] #21003 MimeType compareTo implementation is not compatible with equals

Referenced from: commits 75fe618, 89e504c

[spring-projects-issues]

Sam Brannen commented

FYI: to get the build passing again, I pushed a patch to master for the broken tests.

Analysis

A more robust solution would be to ensure that MimeType either stores all "charset" properties in uppercase (or all in lowercase) or that the implementation of equals() performs case-insensitive comparisons for the names of the "charset" properties.

[spring-projects-issues]

Sam Brannen commented

Fixed in GitHub commit 89e504c:

Use Charset instead of String in MimeType.equals()

Prior to this commit, Spring's MimeType checked for equality between
two MIME types based on the equality of their properties maps; however,
the properties maps contain string representations of the "charset"
values. Thus, "UTF-8" is never equal to "utf-8" which breaks the
contract for character set names which must be compared in a
case-insensitive manner.

This commit addresses this issue by ensuring that "charset" properties
in MimeType instances are compared as Java Charset instances, thereby
ignoring case when checking for equality between charset names.