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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Session</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 2 頁（共8 頁）</nobr></font></td>
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<p>
<code><a href="http://java.sun.com/products/javamail/javadocs/javax/mail/Session.html">Session</a></code> 類定義了一個(gè)基本郵件會(huì)話(session)。所有其它類都是經(jīng)由這個(gè)session 才得以生效。<code>Session</code> 對(duì)象用 <code><a href="http://java.sun.com/products/jdk/1.2/docs/api/java/util/Properties.html">java.util.Properties</a></code> 對(duì)象獲取信息，如郵件服務(wù)器、用戶名、密碼及整個(gè)應(yīng)用程序中共享的其它信息。
</p>
<p>類的構(gòu)造器是私有的(private)。您可以得到單個(gè)缺省 session，它能用 <code>getDefaultInstance()</code> 方法被共享：</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
Properties props = new Properties();
// fill props with any information
Session session = Session.getDefaultInstance(props, null);
</code>
</pre>
<p>或者，您還可以用 <code>getInstance()</code> 創(chuàng)建一個(gè)獨(dú)立的 session：</p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
Properties props = new Properties();
// fill props with any information
Session session = Session.getDefaultInstance(props, null);
</code>
</pre>
<p>對(duì)于這兩種情況，<code>null</code> 參數(shù)都是 <code>Authenticator</code> 對(duì)象（在這次沒有使用）。</p>
<p>對(duì)于大多數(shù)情況，共享的 session 已經(jīng)夠用了，即使要處理多個(gè)用戶郵箱的郵件 session 也一樣。您可以在通信過程中稍后的步驟加入用戶名和密碼組合，讓一切保持獨(dú)立。</p>
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