Cockney represents the basilectal end of the London accent and can be considered the broadest form of London local accent. It traditionally refers only to specific regions and speakers within the city. While many Londoners may speak what is referred to as "popular London" they do not necessarily speak Cockney. The popular Londoner accent can be distinguished from Cockney in a number of ways, and can also be found outside of the capital, unlike the true Cockney accent.
-From the University of Arizona's Language Samples Project website
The following links will take you to sound clips featuring the Cockney dialect from both the IDEA International Dialects of English Archives and The British Library websites . The participants you will be listening to are: 1) "black male, born 1970 in London" 2) "white male, born 1964 in Luton, Bedfordshire" and 3) "male and female school pupils, born 1987, Southwark, London."
This clip from the opening scene of the 1998 film Lock, Stock and Two Smoking Barrels, features the British actor Jason Statham speaking with a decidedly Cockney accent.
The following links will take you to more video clips featuring the Cockney dialect.
Here are some plays with Cockney characters.
Pygmalion and My Fair Lady by 
Major Barbara by The following films and texts are available at Point Park University Library and provide valuable resources for students learning the Cockney Dialect.