What is Wilde's writing style in "The Picture of Dorian Gray"?

Oscar Wilde was a member of the Aesthetic movement, a
movement that said art should exist for its own sake.  Much of what he wrote in
A Picture of Dorian Gray was a reflection of this idea, from its
aphorisms to its ornate prose to the allegorical nature that characterizes the
story.

Wilde uses aphorisms to draw his reader into the
story.  In his Preface, for example, he says, “The artist is the creator of beautiful
things. To reveal art and conceal the artist is art's aim.” In the very first line of
the novel, Wilde tells us that art, the creation of beauty, is what is most important. 
This applies not only to the way he writes, but also to what he writes about. He says,
“Those who find beautiful meanings in beautiful things are the cultivated,” challenging
the reader to find those beautiful meanings. He also challenges the reader to go beneath
the surface of his narrative when he says, “All art is at once surface and symbol. Those
who go beneath the surface do so at their peril.” Telling the reader not to search for
meaning beneath the surface only makes the reader inclined to do just
that.

Wilde’s use of ornate prose throughout the novel is
another great example of the aesthetic style. Wilde could use simpler words, and he
could construct his sentences differently. He does not do this because, after all, part
of his purpose is to write beautifully for the sake of writing beautifully. “I wonder
can you realize all that that means? Unconsciously he defines for me the lines of a
fresh school, a school that is to have in it all the passion of the romantic spirit, all
the perfection of the spirit that is Greek. The harmony of soul and body—how much that
is!” (Chapter 1).  The way Wilde expresses himself is part of the point he is trying to
make about beauty for its own sake.

Finally, the story
Wilde is trying to tell is an allegory.  Why write an allegory when a simple,
straightforward story would do?  In keeping with the aesthetic movement, Wilde
structures the story as an allegory in order to celebrate this style.  Dorian’s story is
the story of an innocent young man who falls from grace as the result of the corruptive
influence of evil in the form of Lord Henry.  Dorian essentially sells his soul to keep
his youth.  In using the portrait as part of the allegory, Oscar Wilde challenges the
reader to discover that art cannot be life, and that beauty for its own sake also has
its flaws.