C# XML操作之一：使用XmlDocument来读写

新建XML，并且写入内容
往已有XML文件中添加内容
2种方法搜索所有title节点，并且打印其内容

所有代码都在同一个类中，含有对象

XmlDocument doc = new XmlDocument();

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新建XML，并且写入内容

        private void button4_Click(object sender, EventArgs e)
        {
            
            doc.AppendChild(doc.CreateXmlDeclaration("1.0", "utf-8", null));
            XmlElement newbook = doc.CreateElement("book");
            newbook.SetAttribute("genre", "Mystery");
            newbook.SetAttribute("publicationdate", "2001");
            newbook.SetAttribute("ISBN", "123345525");

            XmlElement newTitle = doc.CreateElement("title");
            newTitle.InnerText = "The Case of The missing cookie";
            newbook.AppendChild(newTitle);

            XmlElement newAuthor = doc.CreateElement("Author");
            newAuthor.InnerText = "James Lorain";
            newbook.AppendChild(newAuthor);
            if(doc.DocumentElement==null)
                doc.AppendChild(newbook);
            XmlTextWriter tr = new XmlTextWriter("newbook.xml",Encoding.UTF8);
            tr.Formatting = Formatting.Indented;
            doc.WriteContentTo(tr);
            tr.Close();
        }

创建的xml文件内容为

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往已有XML文件中添加内容

原有books.xml内容如下

<?xml version="1.0" encoding="ISO-8859-1"?>
<!--  Copyright w3school.com.cn -->
<!-- W3School.com.cn bookstore example -->
<bookstore>
<book category="children">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="cooking">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="web" cover="paperback">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
<book category="web">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
</bookstore>

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操作代码

　　　　　　　doc.Load("books.xml");
            XmlElement newbook = doc.CreateElement("book");
            newbook.SetAttribute("genre", "Mystery");
            newbook.SetAttribute("publicationdate", "2001");
            newbook.SetAttribute("ISBN", "123345525");

            XmlElement newTitle = doc.CreateElement("title");
            newTitle.InnerText = "The Case of The missing cookie";
            newbook.AppendChild(newTitle);

            XmlElement newAuthor = doc.CreateElement("Authooooor");
            newAuthor.InnerText = "James Lorain";
            newbook.AppendChild(newAuthor);

            doc.DocumentElement.AppendChild(newbook);
            XmlTextWriter tr = new XmlTextWriter("newbook.xml", null);
            tr.Formatting = Formatting.Indented;
            doc.WriteContentTo(tr);
            tr.Close();

结果就是在原来bookstore节点下附加了新的子节点

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2种方法搜索所有title节点，并且打印其内容

效果

            doc.Load("books.xml");
            XmlNodeList nodeList = doc.GetElementsByTagName("title");
　　　　　　　　//下面代码效果完全相同
　　　　　　　XmlNodeList nodeList2 = doc.SelectNodes("/bookstore/book/title");

            foreach (XmlNode node in nodeList)
            {
                content.Items.Add(node.OuterXml);
            }