Java Enterprise Best Practices

Use JavaMail to Search

Efficient searching is vital for many email-based applications, particularly when more than one application shares an email address. The simplest way to find a message in a folder is to retrieve all of them and loop through the resulting Message object array, examining the relevant fields and selecting the messages that are interesting. JavaMail provides a mechanism for searching messages from a message store, using SearchTerm functionality. The SearchTerm object and its descendents are found in the javax.mail.search package. The various SearchTerm objects perform a particular comparison. FromStringTerm , for instance, performs a substring search on a message’s From header. All string comparisons are case-insensitive.

More complex search terms can be created via the AndTerm , OrTerm , and NotTerm objects, which develop arbitrarily complex search criteria. Here’s how I tell when I’m in trouble:

SearchTerm t = new AndTerm(new FromStringTerm("[e-mail]"), 
                           new SubjectTerm("late book"));
Message[  ] msgs = folder.search(t);

What to do after receiving the message is left as an exercise. For maximum performance, search terms should be used wherever possible. This is because more advanced message storage protocols, including IMAP, have native search capabilities. When these are available the JavaMail provider implementation can translate the search terms into a native search command, transmit that command to the server, and have the server do the ...