Javamail Api 简明教程

JavaMail API - Overview

JavaMail API 提供了一个与平台无关且与协议无关的框架，用于构建邮件和消息传递应用程序。JavaMail API 提供了一组抽象类，定义了构成邮件系统的对象。它是一个用于读取、撰写和发送电子邮件的可选包（标准扩展）。

The JavaMail API provides a platform-independent and protocol-independent framework to build mail and messaging applications. The JavaMail API provides a set of abstract classes defining objects that comprise a mail system. It is an optional package (standard extension) for reading, composing, and sending electronic messages.

JavaMail 提供了用于构建到消息传递系统的接口的元素，包括系统组件和界面。虽然此规范未定义任何特定实现，但 JavaMail 确实包含了几个实现 RFC822 和 MIME Internet 消息传递标准的类。这些类作为 JavaMail 类包的一部分进行交付。

JavaMail provides elements that are used to construct an interface to a messaging system, including system components and interfaces. While this specification does not define any specific implementation, JavaMail does include several classes that implement RFC822 and MIME Internet messaging standards. These classes are delivered as part of the JavaMail class package.

以下是 JavaMail API 中支持的一些协议：

Following are some of the protocols supported in JavaMail API:

  1. SMTP: Acronym for Simple Mail Transfer Protocol. It provides a mechanism to deliver email.

  2. POP: Acronym for Post Office Protocol. POP is the mechanism most people on the Internet use to get their mail. It defines support for a single mailbox for each user. RFC 1939 defines this protocol.

  3. IMAP: Acronym for Internet Message Access Protocol. It is an advanced protocol for receiving messages. It provides support for multiple mailbox for each user, in addition to, mailbox can be shared by multiple users. It is defined in RFC 2060.

  4. MIME: Acronym for Multipurpose Internet Mail Extensions. . It is not a mail transfer protocol. Instead, it defines the content of what is transferred: the format of the messages, attachments, and so on. There are many different documents that take effect here: RFC 822, RFC 2045, RFC 2046, and RFC 2047. As a user of the JavaMail API, you usually don’t need to worry about these formats. However, these formats do exist and are used by your programs.

  5. NNTP and Others:There are many protocols that are provided by third-party providers. Some of them are Network News Transfer Protocol (NNTP), Secure Multipurpose Internet Mail Extensions (S/MIME) etc.

这些详细信息将在后续章节中涉及。

Details of these will be covered in the subsequent chapters.

Architecture

如上所述，Java 应用程序使用 JavaMail API 来编写、发送和接收电子邮件。下图说明了 JavaMail 的架构：

As said above the java application uses JavaMail API to compose, send and receive emails.The following figure illustrates the architecture of JavaMail:

architecture

JavaMail API 的抽象机制类似于其他 J2EE API，如 JDBC、JNDI 和 JMS。如上架构图所示，JavaMail API 分为两个主要部分：

The abstract mechanism of JavaMail API is similar to other J2EE APIs, such as JDBC, JNDI, and JMS. As seen the architecture diagram above, JavaMail API is divided into two main parts:

  1. An application-independent part: An application-programming interface (API) is used by the application components to send and receive mail messages, independent of the underlying provider or protocol used.

  2. A service-dependent part: A service provider interface (SPI) speaks the protocol-specific languages, such as SMTP, POP, IMAP, and Network News Transfer Protocol (NNTP). It is used to plug in a provider of an e-mail service to the J2EE platform.