4.Linq to Xml
2024-08-22 23:20:28
目录
1.Linq to Xml函数构造方法
2.创建包含文本节点的Xml文档
3.保存和加载Xml
4.处理Xml片段
5.从数据库中生成XML
1.Linq to Xml函数构造方法
Linq to Xml引入了一种创建xml的方式，叫做函数构建方式（functional construction）,通过这种方式可以以一种类似Xml文档结构的方式快速构建XML。
//使用Linq To XML 函数构建方式创建XML文档
XDocument xdoc = new XDocument(
new XElement("customers",
new XElement("customer",
new XAttribute("ID", "A"),
new XAttribute("City", "New York"),
new XAttribute("Region", "USA"),
new XElement("order",
new XAttribute("Item", "Widget"),
new XAttribute("Price", )
),
new XElement("order",
new XAttribute("Item", "Tire"),
new XAttribute("Price", )
)
),
new XElement("customer",
new XAttribute("ID", "B"),
new XAttribute("City", "Mumbai"),
new XAttribute("Region", "Asia"),
new XElement("order",
new XAttribute("Item", "Oven"),
new XAttribute("Price", )
)
)
)
); Console.WriteLine(xdoc2.ToString());
2.创建包含文本节点的Xml文档
//使用字符串构建包含文本节点的XML文档
XDocument xdocContent = new XDocument(
new XElement("customers",
new XElement("customer",
new XAttribute("ID", "A"),
new XAttribute("City", "New York"),
new XAttribute("Region", "USA"),
"AAA"
),
new XElement("customer",
new XAttribute("ID", "B"),
new XAttribute("City", "Mumbai"),
new XAttribute("Region", "Asia"),
"BBB"
)
)
);
Console.WriteLine(xdocContent.ToString());
3.保存和加载Xml
从文件加载
//使用Linq To XML 函数构建方式创建XML文档
XDocument xdoc = new XDocument(
new XElement("customers",
new XElement("customer",
new XAttribute("ID", "A"),
new XAttribute("City", "New York"),
new XAttribute("Region", "USA"),
new XElement("order",
new XAttribute("Item", "Widget"),
new XAttribute("Price", )
),
new XElement("order",
new XAttribute("Item", "Tire"),
new XAttribute("Price", )
)
),
new XElement("customer",
new XAttribute("ID", "B"),
new XAttribute("City", "Mumbai"),
new XAttribute("Region", "Asia"),
new XElement("order",
new XAttribute("Item", "Oven"),
new XAttribute("Price", )
)
)
)
); //从文件加载
string fileName = "xmltest.xml";
xdoc.Save(fileName);//保存生成的xml文档
XDocument xdoc2 = XDocument.Load(fileName);//加载XML
Console.WriteLine(xdoc2.ToString());
从字符串加载
//注：ID=""A""使用双引号只是为了在@字符串中包含引号，也可以使用转义如ID=\"A\"
string xmlContent = @"
<customers>
<customer ID=""A"" City=""New York"" Region=""USA"">AAA</customer>
<customer ID=""B"" City=""Mumbai"" Region=""Asia"">BBB</customer>
</customers>
"; //使用Parse从字符串加载XML
XDocument xdoc3 = XDocument.Parse(xmlContent);
4.处理Xml片段
处理Xml片段和处理Xml文档一样，只不过把Element当作顶级元素。xml片段可以应用到xml文档或者别的xml片段
//处理XML片段
XElement xcust = new XElement("customer",
new XAttribute("ID", "C"),
new XAttribute("City", "New York"),
new XAttribute("Region", "USA"),
new XElement("order",
new XAttribute("Item", "Widget"),
new XAttribute("Price", )
),
new XElement("order",
new XAttribute("Item", "Tire"),
new XAttribute("Price", )
)
);
string xcustFilePath = "xcust.xml";
xcust.Save(xcustFilePath); XElement xcust2 = XElement.Load(xcustFilePath);
xdoc.Root.Add(xcust2);//xml片段加到xml文档
Console.WriteLine(xcust2);
5.从数据库中生成XML
从数据库中生成XML先添加ADO.NET实体数据模型CustomerOrderEntities，然后利用添加的实体数据模型生成XML
CustomerOrderEntities entity = new CustomerOrderEntities();
XElement xdocSql = new XElement("Customers",
from n in entity.tblCustomer.AsEnumerable()
where n.Region != "Asia"
select new XElement("Customer", new XAttribute("ID", n.ID),
new XAttribute("CustomerName", n.CustomerName),
from o in n.btlOrder
select new XElement("Order", new XAttribute("OrderId", o.OrderId),
new XAttribute("SKU", o.SKU),
new XAttribute("Qty", o.Qty)
)));
Console.WriteLine(xdocSql.ToString());
生成的XML如下
<Customers>
<Customer ID="" CustomerName="tom">
<Order OrderId="111-101" SKU="sku1" Qty="" />
<Order OrderId="111-102" SKU="sku2" Qty="" />
</Customer>
</Customers>
6.查询XML
//使用Linq To XML 函数构建方式创建XML文档
XDocument xdoc = new XDocument(
new XElement("customers",
new XElement("customer",
new XAttribute("ID", "A"),
new XAttribute("City", "New York"),
new XAttribute("Region", "USA"),
new XElement("order",
new XAttribute("Item", "Widget"),
new XAttribute("Price", )
),
new XElement("order",
new XAttribute("Item", "Tire"),
new XAttribute("Price", )
)
),
new XElement("customer",
new XAttribute("ID", "B"),
new XAttribute("City", "Mumbai"),
new XAttribute("Region", "Asia"),
new XElement("order",
new XAttribute("Item", "Oven"),
new XAttribute("Price", )
)
)
)
);
XElement queryResult = (from UserInfo in xdoc.Root.Elements("customer") where UserInfo.Attribute("ID").Value == "A" select UserInfo).SingleOrDefault();
返回的xml节点如下
<customer ID="A" City="New York" Region="USA">
<order Item="Widget" Price="" />
<order Item="Tire" Price="" />
</customer>
Elements()方法返回xml文档或者xml片段的所有一级元素，也可以传递节点名称返回该名称的所有一级元素
Descendants()返回所有级别的子元素，与之相反.Ancestors()返回当前节点以上的所有元素
Attributes()返回所有属性节点，Attributes("ID")返回所有属性为ID的属性节点，如 xdoc.Root.Elements("customer").Attributes("ID")返回元素节点customer的所有ID属性节点
Attribute("ID")返回ID属性节点
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