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<p class="MsoNormal" style="margin-left:57.0pt"><span style="font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">本地接口定义了一个用户用来创建、查找和去除一个</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">的实例。</span></p>
<p class="MsoNormal" style="margin-left:57.0pt;text-indent:-21.0pt;mso-list:l0 level1 lfo1;
tab-stops:list 57.0pt"><span lang="EN-US" style="font-family:
Wingdings">l<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-US">bean</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">的远程接口（</span><span lang="EN-US">remote
interface</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">）</span></p>
<p class="MsoNormal" style="margin-left:57.0pt"><span style="font-family:宋体;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">远程接口定义了在</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">中实现的商业方法。一个用户通过远程接口来访问这些方法。</span></p>
<p class="MsoNormal" style="margin-left:57.0pt;text-indent:-21.0pt;mso-list:l0 level1 lfo1;
tab-stops:list 57.0pt"><span lang="EN-US" style="font-family:
Wingdings">l<span style="font:7.0pt "Times New Roman"">
</span></span><span lang="EN-US">enterprise bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">类</span></p>
<p class="MsoNormal" style="margin-left:57.0pt"><span lang="EN-US">enterprise
bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">类为</span><span lang="EN-US">bean</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">实现商业逻辑。用户通过</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的远程接口来访问这些方法。</span></p>
<p class="MsoNormal"><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">一旦</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">被部署入</span><span lang="EN-US">EJB</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">容器，用户可以调用定义在本地接口中的</span><span lang="EN-US">create</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">（）方法来实例化</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">。本地接口并不是由</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">本身实现的，而是通过容器来实现的。在本地接口中声明的其它方法允许用户寻找一个</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的实例并且在它不再需要时去除</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">实例。</span></p>
<p class="MsoNormal"><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">当</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">初始化后，用户可以调用</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">中的商业逻辑。然而，用户并不直接调用</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">实例中的方法。用户可调用的方法是定义在</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">的远程接口上的，远程接口是由容器来实现的。当用户调用一个方法时，容器收到了请求并代理用户访问</span><span lang="EN-US">bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">实例。</span></p>
<hr>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:12.0pt"><font color="#000080">Enterprise
beans</font></span><font color="#000080"><span style="font-size:12.0pt;font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的类型</span></font><span lang="EN-US" style="font-size:12.0pt"><font color="#000080"><o:p></font></o:p>
</span></b></p>
<p class="MsoNormal"><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">一个</span><span lang="EN-US">enterprise
bean </span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">可以是一个</span><span lang="EN-US">
session bean </span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">或是一个</span><span lang="EN-US">
entity bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">。</span></p>
<p class="MsoNormal"><b><span lang="EN-US"><font color="#000080">Session beans<o:p>
</font>
</o:p>
</span></b></p>
<p class="MsoNormal"><span lang="EN-US">Session beans</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">是一种作为单用户执行的对象，从某种意义上来说一个</span><span lang="EN-US">Session
bean </span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">对于</span><span lang="EN-US">EJB</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">服务器来说就代表了它的那个用户。</span><span lang="EN-US">Session beans</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">可以保持那个用户的状态，也就是说它们保留了用户的信息。使用</span><span lang="EN-US">Session
bean</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的一个典型例子是网上在线商店中的个人购物手推车。当一个购物者选择商品放入“手推车”时</span><span lang="EN-US">session
bean</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">保留着用户选择的一列商品的清单。</span></p>
<p class="MsoNormal"><span lang="EN-US">Session beans</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">的生命周期是短暂的。通常当用户终止会话时，</span><span lang="EN-US">Session
bean</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">就被用户去除掉。</span></p>
<p class="MsoNormal"><span lang="EN-US">Session beans</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">可以是有状态的或是无状态的。无状态的</span><span lang="EN-US">session
beans</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">并不保持某个特定用户的状态。由于无状态的</span><span lang="EN-US">beans</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">并不保持会话状态，因此它可被用于支持多个用户。</span></p>
<p class="MsoNormal"><b><span lang="EN-US"><font color="#000080">Entity beans<o:p>
</font>
</o:p>
</span></b></p>
<p class="MsoNormal"><span lang="EN-US">Entity Beans</span><span style="font-family:
宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">对数据库中的数据提供了一种对象的视图。通常</span><span lang="EN-US">entity
bean</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">代表着关系数据库表集合中的一行。一个</span><span lang="EN-US">entity
bean</span><span style="font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">通常对多个用户提供服务。</span></p>
<p class="MsoNormal"><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">与</span><span lang="EN-US">session
beans</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">不同，</span><span lang="EN-US">entity beans</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">的生命周期相对较长。它们保持着持续（</span><span lang="EN-US">persistent</span><span style="font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">）的状态，只要相应数据存在于数据库中它们就存在，而不论某个特定用户是否需要它。</span></p>
<span style="mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">容器可以管理<span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">entity bean</span><span style="mso-bidi-font-size: 12.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">的持续性（</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">persistence</span><span style="mso-bidi-font-size: 12.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">），或者</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">entity bean</span><span style="mso-bidi-font-size: 12.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">可以自己管理。如果持续性是由</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">entity bean</span><span style="mso-bidi-font-size: 12.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">自己管理的，则</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">bean</span><span style="mso-bidi-font-size: 12.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">开发者必须编写包含调用数据库的代码。</span>
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