很早以前看过一句话：“XML就象空气”，在企业应用开发中XML是一个重要的数据交换标准。而XSD则可以用来校验XML的数据格式是否正确。
一个典型的XSD文件如下：
1 <?xml version="1.0" encoding="UTF-8"?>
2 <!-- edited with XMLSpy v2013 (http://www.altova.com) by () -->
3 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
4 <xs:element name="AWB">
5 <xs:annotation>
6 <xs:documentation>运单</xs:documentation>
7 </xs:annotation>
8 <xs:complexType>
9 <xs:sequence>
10 <xs:element name="AWB-INFO" minOccurs="1" maxOccurs="1">
11 <xs:complexType>
12 <xs:sequence>
13 <xs:element name="AWBPRE">
14 <xs:annotation>
15 <xs:documentation>运单前缀只有输入3位数字</xs:documentation>
16 </xs:annotation>
17 <xs:simpleType>
18 <xs:restriction base="xs:positiveInteger">
19 <xs:totalDigits value="3"/>
20 </xs:restriction>
21 </xs:simpleType>
22 </xs:element>
23 <xs:element name="AWBNO">
24 <xs:annotation>
25 <xs:documentation>运单号只能输入8位数字</xs:documentation>
26 </xs:annotation>
27 <xs:simpleType>
28 <xs:restriction base="xs:positiveInteger">
29 <xs:totalDigits value="8"/>
30 </xs:restriction>
31 </xs:simpleType>
32 </xs:element>
33 </xs:sequence>
34 </xs:complexType>
35 </xs:element>
36 <xs:element name="PART-INFO">
37 <xs:complexType>
38 <xs:sequence>
39 <xs:element name="PARTICIPANT" minOccurs="2" maxOccurs="unbounded">
40 <xs:annotation>
41 <xs:documentation>物流参与者至少要有2个</xs:documentation>
42 </xs:annotation>
43 <xs:complexType>
44 <xs:sequence>
45 <xs:element name="TYPE">
46 <xs:annotation>
47 <xs:documentation>物流参考者类型，只能是A/S/C其中之一</xs:documentation>
48 </xs:annotation>
49 <xs:simpleType>
50 <xs:restriction base="xs:string">
51 <xs:enumeration value="C"/>
52 <xs:enumeration value="S"/>
53 <xs:enumeration value="A"/>
54 </xs:restriction>
55 </xs:simpleType>
56 </xs:element>
57 <xs:element name="ADDRESS" type="AddressType"/>
58 </xs:sequence>
59 </xs:complexType>
60 </xs:element>
61 </xs:sequence>
62 </xs:complexType>
63 </xs:element>
64 </xs:sequence>
65 </xs:complexType>
66 </xs:element>
67 <xs:complexType name="AddressType">
68 <xs:sequence>
69 <xs:element name="Name" type="xs:string"/>
70 <xs:element name="Street" type="xs:string"/>
71 <xs:element name="City" type="xs:string"/>
72 </xs:sequence>
73 </xs:complexType>
74 </xs:schema>
看到这一大段xml，第一反应通常是头晕，幸好这些内容不用纯手动编写，已经有很多现成的工具，比如XmlSpy可以方便的以GUI方式，通过轻点鼠标，拖拖拉拉就能完成XSD的开发。
这是XmlSpy中XSD的可视化设计界面，还能切换不同的视图，比如下面这样:
对于首次接触XmlSpy的朋友，强烈推荐看下安装目录下的Tutorial.pdf，这是一个不错的入门教程，30分钟以前绝对可以快速浏览一遍。
C#中可以方便的使用XSD来验证xml文件的正确性，示例代码如下：
1 using System;
2 using System.Xml;
3
4 namespace XsdValidate
5 {
6 class Program
7 {
8 static void Main(string[] args)
9 {
10 string xmlFile = @"C:\Users\jimmy.yang\Desktop\XMLSPY\TEST\sample.xml";
11 string xsdFile = @"C:\Users\jimmy.yang\Desktop\XMLSPY\TEST\sample.xsd";
12
13 var xsdValidateResult = ValidateXml(xmlFile, xsdFile);
14
15 if (xsdValidateResult.Item1)
16 {
17 Console.WriteLine("校验通过！");
18 }
19 else
20 {
21 Console.WriteLine("校验失败，原因:\n" + xsdValidateResult.Item2);
22 }
23 Console.Read();
24
25 }
26
27 /// <summary>
28 /// 使用xsd验证xml是否正确
29 /// </summary>
30 /// <param name="xmlFilePath">xml文件路径</param>
31 /// <param name="xsdFilePath">xsd文件路径</param>
32 /// <returns></returns>
33 static Tuple<bool, string> ValidateXml(string xmlFilePath, string xsdFilePath)
34 {
35 Tuple<bool, string> result = new Tuple<bool, string>(true, "");
36 XmlReaderSettings st = new XmlReaderSettings();
37 st.ValidationType = ValidationType.Schema;
38 st.Schemas.Add(null, xsdFilePath);
39
40 //设置验证xml出错时的事件。
41 st.ValidationEventHandler += (obj, e) =>
42 {
43 result = new Tuple<bool, string>(false, e.Message);
44 };
45
46 XmlReader xr = XmlReader.Create(xmlFilePath, st);
47 while (xr.Read())
48 {
49 if (xr.IsStartElement())
50 {
51 xr.Read();
52 }
53 }
54 xr.Close();
55 return result;
56 }
57 }
58 }
注意：如果节点采用pattern，即正则表达式验证，比如
<xs:restriction base="xs:string">
<xs:pattern value="^\d{8}$"></xs:pattern>
</xs:restriction>
XMLSpy中，该节点必须填写"^12345678$"才能验证通过，而如果用.NET/JAVA写代码验证的话，^、$能自动识别为"匹配字符开头/结尾"
XSD还能方便的生成c#类，有二种方法：
1、XMLSpy里先打开一个XSD文件，然后 DTD/Schema->Generate Program Code，接下来按提示操作即可
注：XMLSpy生成的c#类太过于复杂，我个人觉得有点啰嗦
2、直接使用vs.net自带的xsd命令
vs.net命令行下，输入
xsd "xsd文件所在的路径" /classes /out:"cs文件的输出目录"
即可生成对应的cs类 ，文中最开头的xsd生成的cs类代码如下：
1 //------------------------------------------------------------------------------
2 // <auto-generated>
3 // This code was generated by a tool.
4 // Runtime Version:4.0.30319.18331
5 //
6 // Changes to this file may cause incorrect behavior and will be lost if
7 // the code is regenerated.
8 // </auto-generated>
9 //------------------------------------------------------------------------------
10
11 using System.Xml.Serialization;
12
13 //
14 // This source code was auto-generated by xsd, Version=4.0.30319.1.
15 //
16
17
18 /// <remarks/>
19 [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.1")]
20 [System.SerializableAttribute()]
21 [System.Diagnostics.DebuggerStepThroughAttribute()]
22 [System.ComponentModel.DesignerCategoryAttribute("code")]
23 [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)]
24 [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)]
25 public partial class AWB {
26
27 private AWBAWBINFO aWBINFOField;
28
29 private AWBPARTICIPANT[] pARTINFOField;
30
31 /// <remarks/>
32 [System.Xml.Serialization.XmlElementAttribute("AWB-INFO")]
33 public AWBAWBINFO AWBINFO {
34 get {
35 return this.aWBINFOField;
36 }
37 set {
38 this.aWBINFOField = value;
39 }
40 }
41
42 /// <remarks/>
43 [System.Xml.Serialization.XmlArrayAttribute("PART-INFO")]
44 [System.Xml.Serialization.XmlArrayItemAttribute("PARTICIPANT", IsNullable=false)]
45 public AWBPARTICIPANT[] PARTINFO {
46 get {
47 return this.pARTINFOField;
48 }
49 set {
50 this.pARTINFOField = value;
51 }
52 }
53 }
54
55 /// <remarks/>
56 [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.1")]
57 [System.SerializableAttribute()]
58 [System.Diagnostics.DebuggerStepThroughAttribute()]
59 [System.ComponentModel.DesignerCategoryAttribute("code")]
60 [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)]
61 public partial class AWBAWBINFO {
62
63 private string aWBPREField;
64
65 private string aWBNOField;
66
67 /// <remarks/>
68 [System.Xml.Serialization.XmlElementAttribute(DataType="positiveInteger")]
69 public string AWBPRE {
70 get {
71 return this.aWBPREField;
72 }
73 set {
74 this.aWBPREField = value;
75 }
76 }
77
78 /// <remarks/>
79 [System.Xml.Serialization.XmlElementAttribute(DataType="positiveInteger")]
80 public string AWBNO {
81 get {
82 return this.aWBNOField;
83 }
84 set {
85 this.aWBNOField = value;
86 }
87 }
88 }
89
90 /// <remarks/>
91 [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.1")]
92 [System.SerializableAttribute()]
93 [System.Diagnostics.DebuggerStepThroughAttribute()]
94 [System.ComponentModel.DesignerCategoryAttribute("code")]
95 public partial class AddressType {
96
97 private string nameField;
98
99 private string streetField;
100
101 private string cityField;
102
103 /// <remarks/>
104 public string Name {
105 get {
106 return this.nameField;
107 }
108 set {
109 this.nameField = value;
110 }
111 }
112
113 /// <remarks/>
114 public string Street {
115 get {
116 return this.streetField;
117 }
118 set {
119 this.streetField = value;
120 }
121 }
122
123 /// <remarks/>
124 public string City {
125 get {
126 return this.cityField;
127 }
128 set {
129 this.cityField = value;
130 }
131 }
132 }
133
134 /// <remarks/>
135 [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.1")]
136 [System.SerializableAttribute()]
137 [System.Diagnostics.DebuggerStepThroughAttribute()]
138 [System.ComponentModel.DesignerCategoryAttribute("code")]
139 [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)]
140 public partial class AWBPARTICIPANT {
141
142 private AWBPARTICIPANTTYPE tYPEField;
143
144 private AddressType aDDRESSField;
145
146 /// <remarks/>
147 public AWBPARTICIPANTTYPE TYPE {
148 get {
149 return this.tYPEField;
150 }
151 set {
152 this.tYPEField = value;
153 }
154 }
155
156 /// <remarks/>
157 public AddressType ADDRESS {
158 get {
159 return this.aDDRESSField;
160 }
161 set {
162 this.aDDRESSField = value;
163 }
164 }
165 }
166
167 /// <remarks/>
168 [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.1")]
169 [System.SerializableAttribute()]
170 [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)]
171 public enum AWBPARTICIPANTTYPE {
172
173 /// <remarks/>
174 C,
175
176 /// <remarks/>
177 S,
178
179 /// <remarks/>
180 A,
181 }
xsd命令还能直接根据xml生成xsd文件，使用方法如下：
xsd c:\sampe.xml /out:c:\
这样会根据sample.xml在c:\生成sample.xsd文件