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<p class="MsoNormal" style="margin-left:57.0pt"><span style="font-family:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">本地接口定義了一個用戶用來創(chuàng)建、查找和去除一個</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">的實例。</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:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">的遠程接口（</span><span lang="EN-US">remote
interface</span><span style="font-family:宋體;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:宋體;
mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">遠程接口定義了在</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">中實現(xiàn)的商業(yè)方法。一個用戶通過遠程接口來訪問這些方法。</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:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">類</span></p>
<p class="MsoNormal" style="margin-left:57.0pt"><span lang="EN-US">enterprise
bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">類為</span><span lang="EN-US">bean</span><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">實現(xiàn)商業(yè)邏輯。用戶通過</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的遠程接口來訪問這些方法。</span></p>
<p class="MsoNormal"><span style="font-family:宋體;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:宋體;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:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">容器，用戶可以調(diào)用定義在本地接口中的</span><span lang="EN-US">create</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">（）方法來實例化</span><span lang="EN-US">bean</span><span style="font-family:宋體;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:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">本身實現(xiàn)的，而是通過容器來實現(xiàn)的。在本地接口中聲明的其它方法允許用戶尋找一個</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的實例并且在它不再需要時去除</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">實例。</span></p>
<p class="MsoNormal"><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">當</span><span lang="EN-US">enterprise
bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">初始化后，用戶可以調(diào)用</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">中的商業(yè)邏輯。然而，用戶并不直接調(diào)用</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">實例中的方法。用戶可調(diào)用的方法是定義在</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">的遠程接口上的，遠程接口是由容器來實現(xiàn)的。當用戶調(diào)用一個方法時，容器收到了請求并代理用戶訪問</span><span lang="EN-US">bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">實例。</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:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的類型</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:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">一個</span><span lang="EN-US">enterprise
bean </span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">可以是一個</span><span lang="EN-US">
session bean </span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">或是一個</span><span lang="EN-US">
entity bean</span><span style="font-family:宋體;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:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">是一種作為單用戶執(zhí)行的對象，從某種意義上來說一個</span><span lang="EN-US">Session
bean </span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">對于</span><span lang="EN-US">EJB</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">服務器來說就代表了它的那個用戶。</span><span lang="EN-US">Session beans</span><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">可以保持那個用戶的狀態(tài)，也就是說它們保留了用戶的信息。使用</span><span lang="EN-US">Session
bean</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">的一個典型例子是網(wǎng)上在線商店中的個人購物手推車。當一個購物者選擇商品放入“手推車”時</span><span lang="EN-US">session
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">保留著用戶選擇的一列商品的清單。</span></p>
<p class="MsoNormal"><span lang="EN-US">Session beans</span><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">的生命周期是短暫的。通常當用戶終止會話時，</span><span lang="EN-US">Session
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">就被用戶去除掉。</span></p>
<p class="MsoNormal"><span lang="EN-US">Session beans</span><span style="font-family:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">可以是有狀態(tài)的或是無狀態(tài)的。無狀態(tài)的</span><span lang="EN-US">session
beans</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">并不保持某個特定用戶的狀態(tài)。由于無狀態(tài)的</span><span lang="EN-US">beans</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">并不保持會話狀態(tài)，因此它可被用于支持多個用戶。</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:
宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:"Times New Roman"">對數(shù)據(jù)庫中的數(shù)據(jù)提供了一種對象的視圖。通常</span><span lang="EN-US">entity
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">代表著關系數(shù)據(jù)庫表集合中的一行。一個</span><span lang="EN-US">entity
bean</span><span style="font-family:宋體;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"">通常對多個用戶提供服務。</span></p>
<p class="MsoNormal"><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"">與</span><span lang="EN-US">session
beans</span><span style="font-family:宋體;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:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">的生命周期相對較長。它們保持著持續(xù)（</span><span lang="EN-US">persistent</span><span style="font-family:宋體;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"">）的狀態(tài)，只要相應數(shù)據(jù)存在于數(shù)據(jù)庫中它們就存在，而不論某個特定用戶是否需要它。</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: 宋體; 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: 宋體; 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">的持續(xù)性（</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋體; 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: 宋體; 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: 宋體; 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: 宋體; 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。如果持續(xù)性是由</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋體; 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: 宋體; 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，則</span><span lang="EN-US" style="mso-bidi-font-size: 12.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋體; 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: 宋體; 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">開發(fā)者必須編寫包含調(diào)用數(shù)據(jù)庫的代碼。</span>
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