Java EE 7 教程 第一部分 簡介 第1章 概述 第1.7節 Java EE 7 APIs

原文：http://docs.oracle.com/javaee/7/tutorial/doc/overview007.htm

翻譯：石卓林 shizhuolin@hotmail.com

注意：此章是1.8章前移而來,不知為什么oracle刪除原1.7開發角色章節

1.7 Java EE 7 APIs

Figure 1⑹ shows the relationships among the Java EE containers.

Figure 1⑹ Java EE Containers

Description of "Figure 1⑹ Java EE Containers"

Figure 1⑺ shows the availability of the Java EE 7 APIs in the web container.

Figure 1⑺ Java EE APIs in the Web Container

Description of "Figure 1⑺ Java EE APIs in the Web Container"

Figure 1⑻ shows the availability of the Java EE 7 APIs in the EJB container.

Figure 1⑻ Java EE APIs in the EJB Container

Description of "Figure 1⑻ Java EE APIs in the EJB Container"

Figure 1⑼ shows the availability of the Java EE 7 APIs in the application client container.

Figure 1⑼ Java EE APIs in the Application Client Container

Description of "Figure 1⑼ Java EE APIs in the Application Client Container"

The following sections give a brief summary of the technologies required by the Java EE platform and the APIs used in Java EE applications.

1.7 Java EE 7 APIs

圖 1⑹ 顯示了Java EE容器之間的關系.

圖 1⑹ Java EE 容器

"圖 1⑹ Java EE 容器"簡介

圖 1⑺ 顯示了在web容器中可使用的Java EE 7 APIs.

圖 1⑺ Web容器中的 Java EE APIs

"圖 1⑺ Web容器中的 Java EE APIs"簡介

圖 1⑻ 顯示了在EJB容器中可用的Java EE 7 APIs.

圖 1⑻ EJB容器中的Java EE APIs

"圖 1⑻ EJB容器中的Java EE APIs"簡介

圖 1⑼顯示了在利用客戶端容器中可用的Java EE 7 APIs.

圖 1⑼ 利用客戶端容器中的Java EE 7 APIs

"圖 1⑼ 利用客戶端容器中的Java EE 7 APIs"簡介

以下章節扼要敘述了Java EE平臺所需技術和Java EE利用中使用的APIs.

1.7.1 Enterprise JavaBeans Technology

An Enterprise JavaBeans (EJB) component, or enterprise bean, is a body of code that has fields and methods to implement modules of business logic. You can think of an enterprise bean as a building block that can be used alone or with other enterprise beans to execute business logic on the Java EE server.

Enterprise beans are either session beans or message-driven beans.

• A session bean represents a transient conversation with a client. When the client finishes executing, the session bean and its data are gone.
• A message-driven bean combines features of a session bean and a message listener, allowing a business component to receive messages asynchronously. Commonly, these are Java Message Service (JMS) messages.

In the Java EE 7 platform, new enterprise bean features include the following:

• Asynchronous local session beans in EJB Lite
• Nonpersistent timers in EJB Lite

The Java EE 7 platform requires Enterprise JavaBeans 3.2 and Interceptors 1.2. The Interceptors specification is part of the EJB specification.

1.7.1 企業JavaBeans技術

1個 企業JavaBeans (EJB)組件或企業bean是1段代碼，其有業務邏輯實行模塊的字段和方法.你可以認為1個企業bean是1個積木構件，它能被單獨使用或作為其他Java EE服務器上的企業beans履行業務邏輯.

企業bean是會話bean或消息驅動bean:

• 會話bean代表與客戶真個1次短暫會話. 當客戶端履行終了, 會話bean和其數據都會消失.
• 消息驅動 bean 結合了消息監聽器和會話bean的功能, 語序業務組件接收異步消息,通常是Java消息服務(JMS)消息.

在Java EE 7平臺中,企業bean包括以下新功能:

• 在EJB精簡版中的異步本地會話bean
• 在EJB精簡版中的非持久性計時器

Java EE 7平臺要求企業JavaBeans 3.2和Interceptors(攔截器) 1.2. 該攔截器規范是EJB規范的1部份.

1.7.2 Java Servlet Technology

Java Servlet technology lets you define HTTP-specific servlet classes. A servlet class extends the capabilities of servers that host applications accessed by way of a request-response programming model. Although servlets can respond to any type of request, they are commonly used to extend the applications hosted by web servers.

In the Java EE 7 platform, new Java Servlet technology features include the following:

• Nonblocking I/O
• HTTP protocol upgrade

The Java EE 7 platform requires Servlet 3.1.

1.7.2 Java Servlet 技術

Java Servlet技術允許你定義基于HTTP規范的servlet類. servlet類作為服務器的功能延伸, 允許通過要求-響應編程模型的方式訪問主機. Although 雖然servlet可以對任何類型的要求作出響應, 但他們通常被用于擴大web服務器托管的利用程序.

在Java EE 7平臺中, Java Servlet技術包括以下新功能:

• 非阻塞 I/O
• HTTP協議升級

Java EE 7平臺要求Servlet 3.1.

1.7.3 JavaServer Faces Technology

JavaServer Faces technology is a user interface framework for building web applications. The main components of JavaServer Faces technology are as follows:

• A GUI component framework.
• A flexible model for rendering components in different kinds of HTML or different markup languages and technologies. A Renderer object generates the markup to render the component and converts the data stored in a model object to types that can be represented in a view.
• A standard RenderKit for generating HTML 4.01 markup.

The following features support the GUI components:

• Input validation
• Event handling
• Data conversion between model objects and components
• Managed model object creation
• Page navigation configuration
• Expression Language (EL)

All this functionality is available using standard Java APIs and XML-based configuration files.

In the Java EE 7 platform, new features of JavaServer Faces technology include the following:

• HTML5-friendly markup
• Faces Flows
• Resource library contracts

The Java EE 7 platform requires JavaServer Faces 2.2 and Expression Language 3.0.

1.7.3 JavaServer Faces 技術

JavaServer Faces 技術是用于構建web利用的UI框架. 以下是JavaServer Faces技術的主要組成部份:

• 1個GUI(圖形用戶界面)組件框架.
• 1個可以在不同類型HTML或不同的標記語言和技術實現中渲染的彈性組件模型. 通過渲染對象為標記來顯示組件并轉換模型對象的存儲數據為可在視圖中顯示的類型.
• 1個用于生成HTML 4.01標記的標準渲染工具包

GUI組件支持以下功能:

• 輸入校驗
• 事件處理
• 模型對象和組件之間的數據轉換
• 管理的模型對象的創建
• 配置頁面導航
• 表達式語言(EL)

所有功能可使用標準的Java API或基于XML的配置文件.

在Java EE 7平臺中, JavaServer Faces技術包括以下新功能:

• 友好HTML5標記
• 瀑布流
• 資源庫契約

Java EE 7平臺要求JavaServer Faces 2.2和Expression Language 3.0.

1.7.4 JavaServer Pages Technology

JavaServer Pages (JSP) technology lets you put snippets of servlet code directly into a text-based document. A JSP page is a text-based document that contains two types of text:

• Static data, which can be expressed in any text-based format, such as HTML or XML
• JSP elements, which determine how the page constructs dynamic content

For information about JSP technology, see the The Java EE 5 Tutorial at http://docs.oracle.com/javaee/5/tutorial/doc/.

The Java EE 7 platform requires JavaServer Pages 2.3 for compatibility with earlier releases but recommends the use of Facelets as the display technology in new applications.

1.7.4 JavaServer頁面技術

JavaServer Pages (JSP) 技術讓你可以在基于文本的文檔中嵌入servlet代碼片斷. JSP頁面是基于文本的文檔,其包括兩種文本類型:

• 靜態數據, 可以表達任意文本格式, 例如HTML或XML
• JSP元素, 用其構建包括動態內容的頁面

關于JSP技術的信息可以查看Java EE 5教程 at http://docs.oracle.com/javaee/5/tutorial/doc/.

Java EE 7 平臺為兼容初期版本要求JavaServer Pages 2.3,但推薦在新利用中使用Facelets顯示技術.

1.7.5 JavaServer Pages Standard Tag Library

The JavaServer Pages Standard Tag Library (JSTL) encapsulates core functionality common to many JSP applications. Instead of mixing tags from numerous vendors in your JSP applications, you use a single, standard set of tags. This standardization allows you to deploy your applications on any JSP container that supports JSTL and makes it more likely that the implementation of the tags is optimized.

JSTL has iterator and conditional tags for handling flow control, tags for manipulating XML documents, internationalization tags, tags for accessing databases using SQL, and tags for commonly used functions.

The Java EE 7 platform requires JSTL 1.2.

1.7.5 JavaServer頁面標準標簽庫

JavaServer頁面標準標簽庫(JSTL)封裝多數JSP利用中常見的核心功能. 這樣就不需要在你的JSP利用中混合使用來自不同廠商的各種標簽. 它是單1的,標準的,標簽集合. 這類標準化允許你部署利用到支持JSTL的任意JSP容器時感覺更容易,更容易對標簽實現進行優化.

JSTL有用于處理控制流的迭代和條件標簽, 用于操作XML文檔的標簽,國際化標簽,通過SQL訪問數據庫的標簽和經常使用功能標簽.

Java EE 7平臺要求JSTL 1.2.

1.7.6 Java Persistence API

The Java Persistence API (JPA) is a Java standards

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