Salesforce Apex代码开发指南

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"salesforce apex language reference" Salesforce Apex 是一种专为 Salesforce 平台设计的、托管的、面向对象的编程语言。它允许开发者在云端编写自定义业务逻辑，类似于 Java 和 C#，但与 Salesforce 的数据模型和事件驱动架构紧密集成。在“Version 21.0: Spring'11”的Force.com Apex Code Developer's Guide中，我们了解到Apex的工作原理、开发过程、使用场景以及限制。Apex是Salesforce平台上的核心组件，让开发者能够创建触发器、类、批处理作业、Web服务和Visualforce页面的后端逻辑。 Apex的开发过程通常包括设计、编码、测试和部署等步骤。开发者可以根据业务需求来决定何时使用Apex，例如，当标准功能不足以满足特定业务流程时，或者需要在数据修改前后执行特定操作时，Apex就会显得非常有用。然而，Apex也有一些限制，例如代码执行时间和资源使用都有严格的限制，这是为了确保整个Salesforce平台的性能和稳定性。了解这些限制对于编写高效的Apex代码至关重要。在新特性方面，文档可能包含了从旧版本到21.0版本的更新和改进，帮助开发者掌握最新工具和技术。 Apex的核心概念包括数据类型、变量、表达式和语句。数据类型分为原始类型（如Integer、Boolean）和sObject类型，sObject用于表示Salesforce的对象。此外，还有集合类型如List和Map，以及枚举类型。在理解规则转换部分，开发者需要知道如何在不同数据类型之间进行转换，并且要关注可能的类型不匹配问题。变量的大小写敏感性是Apex的一个特点，常量则提供不可变的值。表达式是Apex中的基本构建块，包含运算符和操作数，它们决定了代码的行为。表达式的运算符包括算术、比较和逻辑等，每个都有其优先级，需要理解这些规则以避免混淆。 Apex中的注释有助于提高代码的可读性，而赋值语句则用于改变变量的值。此外，条件语句（If-Else）是控制流程的关键，它根据特定条件执行不同的代码块，是编写复杂逻辑的基础。《Force.com Apex Code Developer's Guide》是学习和精通Apex语言的重要参考资料，涵盖了从基础概念到高级特性的全面内容，对任何希望在Salesforce平台上进行开发的人员都极具价值。

You can also use the compileAndTest API call to deploy Apex to a Salesforce production organization.

For more information, see Deploying Apex Scripts on page 429.

Adding Apex Scripts to a Force.com AppExchange App

You can also include an Apex script in an app that you are creating for AppExchange.

Any Apex that is included as part of a package must have at least 75% cumulative test coverage. Each trigger must also have

some test coverage. When you upload your package to AppExchange, all tests are run to ensure that they run without errors.

In addition, all tests are run when the package is installed in the installer's organization. The installer can decide whether or

not to install the package if any tests fail.

In addition, salesforce.com recommends that any AppExchange package that contains Apex be a managed package.

For more information, see the Force.com Quick Reference for Developing Packages. For more information about Apex in managed

packages, see Developing Apex in Managed Packages on page 192.

Note: Packaging Apex classes that contain references to custom labels which have translations: To include the

translations in the package, enable the Translation Workbench and explicitly package the individual languages used

in the translated custom labels. See “Custom Labels Overview” in the Salesforce online help.

When Should I Use Apex?

The Salesforce prebuilt applications provide powerful CRM functionality. In addition, Salesforce provides the ability to

customize the prebuilt applications to ﬁt your organization. However, your organization may have complex business processes

that are unsupported by the existing functionality. When this is the case, the Force.com platform includes a number of ways

for advanced administrators and developers to implement custom functionality. These include Apex, Visualforce, and the Web

services API.

Apex

Use Apex if you want to:

•

Create Web services

•

Create email services

•

Perform complex validation over multiple objects

•

Create complex business processes that are not supported by workﬂow

•

Create custom transactional logic (logic that occurs over the entire transaction, not just with a single record or object)

•

Attach custom logic to another operation, such as saving a record, so that it occurs whenever the operation is executed,

regardless of whether it originates in the user interface, a Visualforce page, or from the Web Services API

Visualforce

Visualforce consists of a tag-based markup language that gives developers a more powerful way of building applications and

customizing the Salesforce user interface. With Visualforce you can:

•

Build wizards and other multistep processes

•

Create your own custom ﬂow control through an application

•

Deﬁne navigation patterns and data-speciﬁc rules for optimal, efﬁcient application interaction

For more information, see the Visualforce Developer's Guide.

Introducing Force.com Apex Code When Should I Use Apex?

Web Services API

Use standard Force.com Web Services API calls if you want to add functionality to a composite application that processes

only one type of record at a time and does not require any transactional control (such as setting a Savepoint or rolling back

changes).

For more information, see the Web Services API Developer's Guide.

What are the Limitations of Apex?

Apex radically changes the way that developers create on-demand business applications, but it is not currently meant to be a

general purpose programming language. As of this release, Apex cannot be used to:

•

Render elements in the user interface other than error messages

•

Change standard functionality—Apex can only prevent the functionality from happening, or add additional functionality

•

Create temporary ﬁles

•

Spawn threads

Tip:

All Apex runs on the Force.com platform, which is a shared resource used by all other organizations. To guarantee

consistent performance and scalability, the execution of Apex is bound by governor limits that ensure no single Apex

execution impacts the overall service of Salesforce. This means all Apex code is limited by the number of operations

(such as DML or SOQL) that it can perform within one process.

All Apex requests return a collection that contains from 1 to 50,000 records. You cannot assume that your code only

works on a single record at a time. Therefore, you must implement programming patterns that take bulk processing

into account. If you do not, you may run into the governor limits.

See Also:

Understanding Execution Governors and Limits

Apex Design Patterns

What's New?

Review the Winter '11 Release Notes for a summary of new and changed Apex features in the Winter '11 release.

Apex Quick Start

Once you have a Developer Edition organization and have chosen which tool you want to use to write your Apex scripts, you

will want to learn some of the core concepts of Apex. Because Apex is very similar to Java, you may recognize much of the

functionality.

After reviewing the basics, you are ready to write your ﬁrst Apex program—a very simple “Hello World” script. After you

write the script you can expand it, with unit tests.

In addition, there is a more complex shipping invoice example that you can also walk through. This example illustrates many

more features of the language.

Introducing Force.com Apex Code What are the Limitations of Apex?

Naming Variables, Methods and Classes

You cannot use any of the Apex reserved keywords when naming variables, methods or classes. These include words that are

part of Apex and the Force.com platform, such as list, test, or account, as well as reserved keywords.

Using Variables and Expressions

Apex is a strongly-typed language, that is, you must declare the data type of a variable when you ﬁrst refer to it. Apex data types

include basic types such as Integer, Date, and Boolean, as well as more advanced types such as lists, maps, objects and sObjects.

Variables are declared with a name and a data type. You can assign a value to a variable when you declare it. You can also

assign values later. Use the following syntax when declaring variables:

datatype variable_name [ = value];

Tip: Note that the semi-colon at the end of the above is not optional. You must end all statements with a semi-colon.

The following are examples of variable declarations:

// The following variable has the data type of Integer with the name Count,

// and has the value of 0.

Integer Count = 0;

// The following variable has the data type of Decimal with the name Total. Note

// that no value has been assigned to it.

Decimal Total;

// The following variable is an account, which is also referred to as an sObject.

Account MyAcct = new Account();

Also note that all primitive variables are passed by value, while all non-primitive data types are passed by reference.

Using Statements

A statement is any coded instruction that performs an action.

In Apex, statements must end with a semicolon and can be one of the following types:

•

Assignment, such as assigning a value to a variable

•

Conditional (if-else)

•

Loops

- Do-while

- While

- For

•

Locking

•

Data Manipulation Language (DML)

•

Transaction Control

•

Method Invoking

•

Exception Handling

A block is a series of statements that are grouped together with curly braces and can be used in any place where a single statement

would be allowed. For example:

if (true) {

System.debug(1);

System.debug(2);

Introducing Force.com Apex Code Understanding Apex Core Concepts

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