怎么样合并多个文件？
下面的例子通过外部实体引用，将文件order1.xml与文件order2.xml合并为一个文件directory.xml 清单1. 要合并的xml文档order1.xml：
<?xml version="1.0" encoding="GB2312"?>
<order> <item> <itemNumber>ksu-0384</itemNumber> <description>LCD液晶显示器</description> <quantity>1</quantity> <price>358.00</price> </item> <item> <itemNumber>ksu-0511</itemNumber> <description>音箱</description> <quantity>1</quantity> <price>16.50</price> </item> <item> <itemNumber>ksu-7710</itemNumber> <description>鼠标</description> <quantity>1</quantity> <price>8.50</price> </item> </order>
清单2. 要合并的xml文档order2.xml： <?xml version="1.0" encoding="GB2312"?>
<order> <item> <itemNumber>ksu-0652</itemNumber> <description>双飞燕键盘</description> <quantity>1</quantity> <price>35.00</price> </item> <item> <itemNumber>ksu-7720</itemNumber> <description>intel CPU</description> <quantity>1</quantity> <price>1650.00</price> </item> <item> <itemNumber>ksu-7010</itemNumber> <description>迈拓硬盘</description> <quantity>1</quantity> <price>850.00</price> </item> </order>
清单3. 输出文档directory.xml，黑体字部分为实体声明及其引用：
<?xml version="1.0"?> <!DOCTYPE directory [ <!ENTITY disclaimer1 SYSTEM "./order1.xml"> <!ENTITY disclaimer2 SYSTEM "./order2.xml"> ]> <directory> &disclaimer1; &disclaimer2; </directory> 当符合 XML 1.0 的处理器读取文档时，就会扩展实体，用它的内容代替引用，因此完整的文档如下所示。 清单4. 带有扩展实体的文档显示（IE6中）：
<?xml version="1.0" ?> <!DOCTYPE directory (View Source for full doctype...)> - <directory> - <order> - <item> <itemNumber>ksu-0384</itemNumber> <description>LCD液晶显示器</description> <quantity>1</quantity> <price>358.00</price> </item> - <item> <itemNumber>ksu-0511</itemNumber> <description>音箱</description> <quantity>1</quantity> <price>16.50</price> </item> - <item> <itemNumber>ksu-7710</itemNumber> <description>鼠标</description> <quantity>1</quantity> <price>8.50</price> </item> </order> - <order> - <item> <itemNumber>ksu-0652</itemNumber> <description>双飞燕键盘</description> <quantity>1</quantity> <price>35.00</price> </item> - <item> <itemNumber>ksu-7720</itemNumber> <description>intel CPU</description> <quantity>1</quantity> <price>1650.00</price> </item> - <item> <itemNumber>ksu-7010</itemNumber> <description>迈拓硬盘</description> <quantity>1</quantity> <price>850.00</price> </item> </order> </directory>