RESTful实现逻辑？

I have an online mysql database. I understand that to connect to it from an android app, I need to use a REST web service. From what I understood until now is that I have to use a REST webservice + JSON and Jquery to handle everything. But the things that I dont understand are:

• do I need any coding to be done on my mysql web host domain?
• this REST web service needs to be coded within my android app?
• Do I need an apache http client, and that needs to be coded on my app or on the web host?

You're confusing database access, server side code and REST.

It is best practice not to go around directly connecting to databases from a client, especially a "locationally diverse" one.

Your architecture may look like

Android app ---HTTPS REST Verbs---> RESTful Webservices on server, hosed on Apache, Tomcat etc. --- Data access, be it via PDO, JDBC, JPA, whatever ---> mySQL.

The RESTful part really is optional, you can call into whatever you like if you're using an URL.