1.Getter Methods
Getter methods return values from a controller. Every value that is calculated by a controller and displayed in a page must have a corresponding getter method, including any Boolean variables.Getter methods must always be named getVariable.This method allows the page markup to reference the account member variable in the controller class with {! } notation.
It’s a best practice for getter methods to be idempotent, that is, to not have side effects. For example, don’t increment a variable, write a log message, or add a new record to the database.Visualforce doesn’t define the order in which getter methods are called, or how many times they might be called in the course of processing a request.Design your getter methods to produce the same outcome, whether they are called once or multiple times for a single page request.
2.Setter Methods
Setter methods pass user-specified values from page markup to a controller. Any setter methods in a controller are automatically executed before any action methods.While a getter method is always required to access values from a controller, it’s not always necessary to include a setter method to pass values into a controller.If a Visualforce component is bound to an sObject that is stored in a controller, the sObject‘s fields are automatically set if changed by the user, as long as the sObject is saved or updated by a corresponding action method.Setter methods must always be named setVariable.
3.Note the following considerations when creating controller extensions and custom controllers:
Unless a class has a method defined as webService, custom extension and controller classes and methods are generally defined as public. If a class includes a web service method, it must be defined as global.
• Use sets, maps, or lists when returning data from the database. This makes your code more efficient because the code makes fewer trips to the database.
• The Apex governor limits for Visualforce controller extensions and custom controllers are the same as the limits for anonymous block or WSDL methods. For more information about governor limits, see Understanding Execution Governors and Limits in the Appendix.
• If you are building a custom controller or controller extension, be careful that you do not inadvertently expose sensitive data that would normally be hidden from users. Consider using the with sharing keywords on class definitions to enforce permissions.Also be careful using Web services, which are secured as top-level entry points by the profile, but execute in the system context once they are initiated.
• Apex methods and variables are not instantiated in a guaranteed order. For more information, see Getting and Setting Data with a Custom Extension or Controller on page 84.
• You can‘t use data manipulation language (DML) operations in a “getxxx” method in a controller. For example, if your controller had a getName method, you could not use insert or update in the method to create an object.
• You can‘t use data manipulation language (DML) operations in a constructor method in a controller.
• You can‘t use the @future annotation in a “getxxx” or “setxxx” method in a controller, or in the constructor for a controller.
• Primitive Apex data types such as String or Integer are passed by value to the component‘s controller.
• Non-primitive Apex data types such as lists and sObjects are passed by reference to component‘s controller. This means that if component‘s controller changes the name of an account, the changes are available in page‘s controller.
• If your org uses person accounts
– When referencing an account record‘s name field with a custom controller using the <apex:inputField> component you must specify isPersonAccount in your query.
– If you create a new account and set name, the record will be a business account. If you create a new account and set lastname,it will be a person account.
– As a best practice, create a custom name formula field that will render properly for both person accounts and business accounts,then use that field instead of the standard field in your Visualforce pages.
– If you plan on including your Visualforce page in a Force.com AppExchange package, in your controller or controller extension,you cannot explicitly reference fields that exist only in a person account.
原文：http://www.cnblogs.com/Aaronqcd/p/4362508.html