LINQ to XML一些基本查询
Code
/**/////根据元素的名称进行筛选（有命名空间）
//XNamespace aw = "http://www.adventure-works.com";
//XElement po = XElement.Load("PurchaseOrderInNamespace.xml");
//IEnumerable<XElement> items =
// from el in po.Descendants(aw + "ProductName")
// select el;
//foreach (XElement prdName in items)
// Console.WriteLine(prdName.Name + ":" + (string)prdName);
/**/////链接轴方法
//XElement purchaseOrders = XElement.Load("PurchaseOrders.xml");
//IEnumerable<XElement> names =
// from el in purchaseOrders
// .Elements("PurchaseOrder")
// .Elements("Address")
// .Elements("Name")
// select el;
//foreach (XElement e in names)
// Console.WriteLine(e);
/**/////链接轴方法,有时，当可能存在或不存在间隔上级时，您希望在特定的元素深度，检索所有的元素
//XElement root = XElement.Load("Irregular.xml");
//IEnumerable<XElement> configParameters =
// root.Elements("Customer").Elements("Config").
// Elements("ConfigParameter");
//foreach (XElement cp in configParameters)
// Console.WriteLine(cp);
/**/////检索单个子元素
//XElement po = XElement.Load("PurchaseOrder.xml");
//XElement e = po.Element("DeliveryNotes");
//Console.WriteLine(e);
/**/////检索索性的集合
//XElement val = new XElement("Value",
// new XAttribute("ID", "1243"),
// new XAttribute("Type", "int"),
// new XAttribute("ConvertableTo", "double"),
// "100");
//IEnumerable<XAttribute> listOfAttributes =
// from att in val.Attributes()
// select att;
//foreach (XAttribute a in listOfAttributes)
// Console.WriteLine(a);
/**/////检索单个属性
//XElement cust = new XElement("PhoneNumbers",
// new XElement("Phone",
// new XAttribute("type", "home"),
// "555-555-5555"),
// new XElement("Phone",
// new XAttribute("type", "work"),
// "555-555-6666")
// );
//IEnumerable<XElement> elList =
// from el in cust.Descendants("Phone")
// select el;
//foreach (XElement el in elList)
// Console.WriteLine((string)el.Attribute("type"));
/**/////检索属性值
//XElement root = new XElement("Root",
// new XAttribute("Attr", "abcde")
// );
//Console.WriteLine(root);
//string str = (string)root.Attribute("Attr");
//Console.WriteLine(str);
#endregion
基本查询#region 基本查询
/**/////查找具有特定属性的元素
//XElement root = XElement.Load("PurchaseOrder.xml");
//IEnumerable<XElement> address =
// from el in root.Elements("Address")
// where (string)el.Attribute("Type") == "Billing"
// select el;
//foreach (XElement el in address)
// Console.WriteLine(el);
/**/////查找具有特定子元素的元素
//XElement root = XElement.Load("TestConfig.xml");
//IEnumerable<XElement> tests =
// from el in root.Elements("Test")
// where (string)el.Element("CommandLine") == "Examp2.EXE"
// select el;
//foreach (XElement el in tests)
// Console.WriteLine((string)el.Attribute("TestId"));
//查询 XDocument 与查询 XElement
// //Create a simple document and write it to a file
// File.WriteAllText("Test.xml", @"<Root>
// <Child1>1</Child1>
// <Child2>2</Child2>
// <Child3>3</Child3>
// </Root>");
//Console.WriteLine("Querying tree loaded with XElement.Load");
//Console.WriteLine("----");
//XElement doc = XElement.Load("Test.xml");
//IEnumerable<XElement> childList =
// from el in doc.Elements()
// select el;
//foreach (XElement e in childList)
// Console.WriteLine(e);
//Console.WriteLine("Querying tree loaded with XDocument.Load");
//Console.WriteLine("----");
//XDocument doc = XDocument.Load("Test.xml");
//IEnumerable<XElement> childList =
// from el in doc.Elements()
// select el;
//foreach (XElement e in childList)
// Console.WriteLine(e);
// //查找具有特定元素名称的子代
// XElement root = XElement.Parse(@"<root>
// <para>
// <r>
// <t>Some text </t>
// </r>
// <n>
// <r>
// <t>that is broken up into </t>
// </r>
// </n>
// <n>
// <r>
// <t>multiple segments.</t>
// </r>
// </n>
// </para>
// </root>");
// IEnumerable<string> textSegs =
// from seg in root.Descendants("t")
// select (string)seg;
// string str = textSegs.Aggregate(new StringBuilder(),
// (sb, i) => sb.Append(i),
// sp => sp.ToString()
// );
// Console.WriteLine(str);
// //使用 Descendants 方法查找单个后代
// XElement root = XElement.Parse(@"<Root>
// <Child1>
// <GrandChild1>GC1 Value</GrandChild1>
// </Child1>
// <Child2>
// <GrandChild2>GC2 Value</GrandChild2>
// </Child2>
// <Child3>
// <GrandChild3>GC3 Value</GrandChild3>
// </Child3>
// <Child4>
// <GrandChild4>GC4 Value</GrandChild4>
// </Child4>
// </Root>");
// string grandChild3 = (string)
// (from el in root.Descendants("GrandChild3")
// select el).First();
// Console.WriteLine(grandChild3);
/**/////编写使用复杂筛选的查询
//XElement root = XElement.Load("PurchaseOrders.xml");
//IEnumerable<XElement> purchaseOrders =
// from el in root.Elements("PurchaseOrder")
// where
// (from add in el.Elements("Address")
// where
// (string)add.Attribute("Type") == "Shipping" &&
// (string)add.Element("State") == "NY"
// select add)
// .Any()
// select el;
//foreach (XElement el in purchaseOrders)
// Console.WriteLine((string)el.Attribute("PurchaseOrderNumber"));
// //筛选可选元素
// XElement root = XElement.Parse(@"<Root>
// <Child1>
// <Text>Child One Text</Text>
// <Type Value=""Yes""/>
// </Child1>
// <Child2>
// <Text>Child Two Text</Text>
// <Type Value=""Yes""/>
// </Child2>
// <Child3>
// <Text>Child Three Text</Text>
// <Type Value=""No""/>
// </Child3>
// <Child4>
// <Text>Child Four Text</Text>
// <Type Value=""Yes""/>
// </Child4>
// <Child5>
// <Text>Child Five Text</Text>
// </Child5>
// </Root>");
// var cList =
// from typeElement in root.Elements().Elements("Type")
// where (string)typeElement.Attribute("Value") == "Yes"
// select (string)typeElement.Parent.Element("Text");
// foreach (string str in cList)
// Console.WriteLine(str);
/**/////对元素进行排序
//XElement root = XElement.Load("Data.xml");
//IEnumerable<decimal> prices =
// from el in root.Elements("Data")
// let price = (decimal)el.Element("Price")
// orderby price
// select price;
//foreach (decimal el in prices)
// Console.WriteLine(el);
/**/////对多个键上的元素进行排序
//XElement co = XElement.Load("CustomersOrders.xml");
//var sortedElements =
// from c in co.Element("Orders").Elements("Order")
// orderby (string)c.Element("ShipInfo").Element("ShipPostalCode"),
// (DateTime)c.Element("OrderDate")
// select new
// {
// CustomerID = (string)c.Element("CustomerID"),
// EmployeeID = (string)c.Element("EmployeeID"),
// ShipPostalCode = (string)c.Element("ShipInfo").Element("ShipPostalCode"),
// OrderDate = (DateTime)c.Element("OrderDate")
// };
//foreach (var r in sortedElements)
// Console.WriteLine("CustomerID:{0} EmployeeID:{1} ShipPostalCode:{2} OrderDate:{3:d}",
// r.CustomerID, r.EmployeeID, r.ShipPostalCode, r.OrderDate);
//计算中间值
//XElement root = XElement.Load("Data.xml");
//IEnumerable<decimal> extensions =
// from el in root.Elements("Data")
// let extension = (decimal)el.Element("Quantity") * (decimal)el.Element("Price")
// where extension >= 25
// orderby extension
// select extension;
//foreach (decimal ex in extensions)
// Console.WriteLine(ex);
// // 编写基于上下文查找元素的查询
// XElement doc = XElement.Parse(@"<Root>
// <p id=""1""/>
// <ul>abc</ul>
// <Child>
// <p id=""2""/>
// <notul/>
// <p id=""3""/>
// <ul>def</ul>
// <p id=""4""/>
// </Child>
// <Child>
// <p id=""5""/>
// <notul/>
// <p id=""6""/>
// <ul>abc</ul>
// <p id=""7""/>
// </Child>
// </Root>");
// IEnumerable<XElement> items =
// from e in doc.Descendants("p")
// let z = e.ElementsAfterSelf().FirstOrDefault()
// where z != null && z.Name.LocalName == "ul"
// select e;
// foreach (XElement e in items)
// Console.WriteLine("id = {0}", (string)e.Attribute("id"));
//调试空查询结果集
// XElement root = XElement.Parse(
// @"<Root xmlns='http://www.adventure-works.com'>
// <Child>1</Child>
// <Child>2</Child>
// <Child>3</Child>
// <AnotherChild>4</AnotherChild>
// <AnotherChild>5</AnotherChild>
// <AnotherChild>6</AnotherChild>
// </Root>");
// IEnumerable<XElement> c1 =
// from el in root.Elements("Child")
// select el;
// Console.WriteLine("Result set follows:");
// foreach (XElement el in c1)
// Console.WriteLine((int)el);
// Console.WriteLine("End of result set");
// XElement root = XElement.Parse(
// @"<Root xmlns='http://www.adventure-works.com'>
// <Child>1</Child>
// <Child>2</Child>
// <Child>3</Child>
// <AnotherChild>4</AnotherChild>
// <AnotherChild>5</AnotherChild>
// <AnotherChild>6</AnotherChild>
// </Root>");
// XNamespace aw = "http://www.adventure-works.com";
// IEnumerable<XElement> c1 =
// from el in root.Elements(aw + "Child")
// select el;
// Console.WriteLine("Result set follows:");
// foreach (XElement el in c1)
// Console.WriteLine((int)el);
// Console.WriteLine("End of result set");
#endregion
投影和转换#region 投影和转换
//通过 LINQ to XML 使用字典
//Dictionary<string, string> dict = new Dictionary<string, string>();
//dict.Add("Child1", "Value1");
//dict.Add("Child2", "Value2");
//dict.Add("Child3", "Value3");
//dict.Add("Child4", "Value4");
//XElement root = new XElement("Root",
// from keyValue in dict
// select new XElement(keyValue.Key, keyValue.Value)
//);
//Console.WriteLine(root);
//XElement root = new XElement("Root",
// new XElement("Child1", "Value1"),
// new XElement("Child2", "Value2"),
// new XElement("Child3", "Value3"),
// new XElement("Child4", "Value4")
//);
//Dictionary<string, string> dict = new Dictionary<string, string>();
//foreach (XElement el in root.Elements())
// dict.Add(el.Name.LocalName, el.Value);
//foreach (string str in dict.Keys)
// Console.WriteLine("{0}:{1}", str, dict[str]);
/**/////转换 XML 树的形状
//XElement co = XElement.Load("CustomersOrders.xml");
//XElement newCustOrd =
// new XElement("Root",
// from cust in co.Element("Customers").Elements("Customer")
// select new XElement("Customer",
// cust.Attributes(),
// cust.Elements(),
// new XElement("Orders",
// from ord in co.Element("Orders").Elements("Order")
// where (string)ord.Element("CustomerID") == (string)cust.Attribute("CustomerID")
// select new XElement("Order",
// ord.Attributes(),
// ord.Element("EmployeeID"),
// ord.Element("OrderDate"),
// ord.Element("RequiredDate"),
// ord.Element("ShipInfo")
// )
// )
// )
// );
//Console.WriteLine(newCustOrd);
/**/////投影匿名类型
//XElement custOrd = XElement.Load("CustomersOrders.xml");
//var custList =
// from el in custOrd.Element("Customers").Elements("Customer")
// select new
// {
// CustomerID = (string)el.Attribute("CustomerID"),
// CompanyName = (string)el.Element("CompanyName"),
// ContactName = (string)el.Element("ContactName")
// };
//foreach (var cust in custList)
// Console.WriteLine("{0}:{1}:{2}", cust.CustomerID, cust.CompanyName, cust.ContactName);
/**/////从 XML 生成文本文件
//XElement custOrd = XElement.Load("CustomersOrders.xml");
//string csv =
// (from el in custOrd.Element("Customers").Elements("Customer")
// select
// String.Format("{0},{1},{2},{3},{4},{5},{6},{7},{8},{9}{10}",
// (string)el.Attribute("CustomerID"),
// (string)el.Element("CompanyName"),
// (string)el.Element("ContactName"),
// (string)el.Element("ContactTitle"),
// (string)el.Element("Phone"),
// (string)el.Element("FullAddress").Element("Address"),
// (string)el.Element("FullAddress").Element("City"),
// (string)el.Element("FullAddress").Element("Region"),
// (string)el.Element("FullAddress").Element("PostalCode"),
// (string)el.Element("FullAddress").Element("Country"),
// Environment.NewLine
// )
// )
// .Aggregate(
// new StringBuilder(),
// (sb, s) => sb.Append(s),
// sb => sb.ToString()
// );
//Console.WriteLine(csv);
// //从 CSV 文件生成 XML
// // Create the text file.
// string csvString = @"GREAL,Great Lakes Food Market,Howard Snyder,Marketing Manager,(503) 555-7555,2732 Baker Blvd.,Eugene,OR,97403,USA
// HUNGC,Hungry Coyote Import Store,Yoshi Latimer,Sales Representative,(503) 555-6874,City Center Plaza 516 Main St.,Elgin,OR,97827,USA
// LAZYK,Lazy K Kountry Store,John Steel,Marketing Manager,(509) 555-7969,12 Orchestra Terrace,Walla Walla,WA,99362,USA
// LETSS,Let's Stop N Shop,Jaime Yorres,Owner,(415) 555-5938,87 Polk St. Suite 5,San Francisco,CA,94117,USA";
// File.WriteAllText("cust.csv", csvString);
// // Read into an array of strings.
// string[] source = File.ReadAllLines("cust.csv");
// XElement cust = new XElement("Root",
// from str in source
// let fields = str.Split(',')
// select new XElement("Customer",
// new XAttribute("CustomerID", fields[0]),
// new XElement("CompanyName", fields[1]),
// new XElement("ContactName", fields[2]),
// new XElement("ContactTitle", fields[3]),
// new XElement("Phone", fields[4]),
// new XElement("FullAddress",
// new XElement("Address", fields[5]),
// new XElement("City", fields[6]),
// new XElement("Region", fields[7]),
// new XElement("PostalCode", fields[8]),
// new XElement("Country", fields[9])
// )
// )
// );
// Console.WriteLine(cust);
#endregion
高级查询技术#region 高级查询技术
/**/////联接两个集合
//XmlSchemaSet schemas = new XmlSchemaSet();
//schemas.Add("", "CustomersOrders.xsd");
//Console.Write("Attempting to validate, ");
//XDocument custOrdDoc = XDocument.Load("CustomersOrders.xml");
//bool errors = false;
//custOrdDoc.Validate(schemas, (o, e) =>
//{
// Console.WriteLine("{0}", e.Message);
// errors = true;
//});
//Console.WriteLine("custOrdDoc {0}", errors ? "did not validate" : "validated");
//if (!errors)
//{
// // Join customers and orders, and create a new XML document with
// // a different shape.
// // The new document contains orders only for customers with a
// // CustomerID > 'K'
// XElement custOrd = custOrdDoc.Element("Root");
// XElement newCustOrd = new XElement("Root",
// from c in custOrd.Element("Customers").Elements("Customer")
// join o in custOrd.Element("Orders").Elements("Order")
// on (string)c.Attribute("CustomerID") equals
// (string)o.Element("CustomerID")
// where ((string)c.Attribute("CustomerID")).CompareTo("K") > 0
// select new XElement("Order",
// new XElement("CustomerID", (string)c.Attribute("CustomerID")),
// new XElement("CompanyName", (string)c.Element("CompanyName")),
// new XElement("ContactName", (string)c.Element("ContactName")),
// new XElement("EmployeeID", (string)o.Element("EmployeeID")),
// new XElement("OrderDate", (DateTime)o.Element("OrderDate"))
// )
// );
// Console.WriteLine(newCustOrd);
//}
/**/////使用分组创建层次结构
//XElement doc = XElement.Load("Data.xml");
//var newData =
// new XElement("Root",
// from data in doc.Elements("Data")
// group data by (string)data.Element("Category") into groupedData
// select new XElement("Group",
// new XAttribute("ID", groupedData.Key),
// from g in groupedData
// select new XElement("Data",
// g.Element("Quantity"),
// g.Element("Price")
// )
// )
// );
//Console.WriteLine(newData);
/**/////执行文本到 XML 的流式转换
//StreamReader sr = new StreamReader("People.txt");
//XStreamingElement xmlTree = new XStreamingElement("Root",
// from line in sr.Lines()
// let items = line.Split(',')
// where !line.StartsWith("#")
// select new XElement("Person",
// new XAttribute("ID", items[0]),
// new XElement("First", items[1]),
// new XElement("Last", items[2]),
// new XElement("Occupation", items[3])
// )
//);
//Console.WriteLine(xmlTree);
//sr.Close();
/**/////使用 XPath 查询 LINQ to XML
//XElement root = new XElement("Root",
// new XElement("Child1", 1),
// new XElement("Child1", 2),
// new XElement("Child1", 3),
// new XElement("Child2", 4),
// new XElement("Child2", 5),
// new XElement("Child2", 6)
//);
//IEnumerable<XElement> list = root.XPathSelectElements("./Child2");
//foreach (XElement el in list)
// Console.WriteLine(el);
#endregion
修改XML树#region 修改XML树
/**/////将属性转换为元素
//XElement root = XElement.Load("Data1.xml");
//foreach (XAttribute att in root.Attributes())
//{
// root.Add(new XElement(att.Name, (string)att));
//}
//root.Attributes().Remove();
//Console.WriteLine(root);
/**/////函数构造
//XElement root = XElement.Load("Data1.xml");
//XElement newTree = new XElement("Root",
// root.Element("Child1"),
// from att in root.Attributes()
// select new XElement(att.Name, (string)att)
//);
//Console.WriteLine(newTree);
/**/////向树中添加元素
//XElement srcTree = new XElement("Root",
// new XElement("Element1", 1),
// new XElement("Element2", 2),
// new XElement("Element3", 3),
// new XElement("Element4", 4),
// new XElement("Element5", 5)
//);
//XElement xmlTree = new XElement("Root",
// new XElement("Child1", 1),
// new XElement("Child2", 2),
// new XElement("Child3", 3),
// new XElement("Child4", 4),
// new XElement("Child5", 5)
//);
//xmlTree.Add(new XElement("NewChild", "new content"));
//xmlTree.Add(
// from el in srcTree.Elements()
// where (int)el > 3
// select el
//);
/**///// Even though Child9 does not exist in srcTree, the following statement will not
//// throw an exception, and nothing will be added to xmlTree.
//xmlTree.Add(srcTree.Element("Child9"));
//Console.WriteLine(xmlTree);
//移除元素
// XElement root = XElement.Parse(@"<Root>
// <Child1>
// <GrandChild1/>
// <GrandChild2/>
// <GrandChild3/>
// </Child1>
// <Child2>
// <GrandChild4/>
// <GrandChild5/>
// <GrandChild6/>
// </Child2>
// <Child3>
// <GrandChild7/>
// <GrandChild8/>
// <GrandChild9/>
// </Child3>
// </Root>");
// root.Element("Child1").Element("GrandChild1").Remove();
// root.Element("Child2").Elements().ToList().Remove();
// root.Element("Child3").Elements().Remove();
// Console.WriteLine(root);
/**/////维护名称/值对
//// Create an element with no content.
//XElement root = new XElement("Root");
/**///// Add a number of name/value pairs as attributes.
//root.SetAttributeValue("Top", 22);
//root.SetAttributeValue("Left", 20);
//root.SetAttributeValue("Bottom", 122);
//root.SetAttributeValue("Right", 300);
//root.SetAttributeValue("DefaultColor", "Color.Red");
//Console.WriteLine(root);
/**///// Replace the value of Top.
//root.SetAttributeValue("Top", 10);
//Console.WriteLine(root);
/**///// Remove DefaultColor.
//root.SetAttributeValue("DefaultColor", null);
//Console.WriteLine(root);
/**/////元素名称/值对
//// Create an element with no content.
//XElement root = new XElement("Root");
/**///// Add a number of name/value pairs as elements.
//root.SetElementValue("Top", 22);
//root.SetElementValue("Left", 20);
//root.SetElementValue("Bottom", 122);
//root.SetElementValue("Right", 300);
//root.SetElementValue("DefaultColor", "Color.Red");
//Console.WriteLine(root);
//Console.WriteLine("----");
/**///// Replace the value of Top.
//root.SetElementValue("Top", 10);
//Console.WriteLine(root);
//Console.WriteLine("----");
/**///// Remove DefaultColor.
//root.SetElementValue("DefaultColor", null);
//Console.WriteLine(root);
#endregion
原文地址：https://www.cnblogs.com/zwl12549/p/1324571.html