测试源代码如下,使用 VS2013 编写。
using System;
using System.Collections;
using System.Collections.Generic;
using System.Xml.Serialization;
using System.IO;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
var f = new XmlSerializer(typeof(TestClass), new[] { typeof(DerivedClass1), typeof(ChildNS.DerivedClass1) });
var ns = new XmlSerializerNamespaces();
ns.Add("ns", "http://yourcompany.org/schemas/ns");
ns.Add("nsc", "http://yourcompany.org/schemas/ns/child");
ns.Add("xsi", "http://www.w3.org/2001/XMLSchema-instance");
using (var sw = new StringWriter())
{
f.Serialize(sw, new TestClass(), ns);
Console.WriteLine(sw.ToString());
}
}
}
public class TestClass
{
public BaseClass BaseTest = new BaseClass();
public BaseClass BaseTest1 = new DerivedClass1();
[XmlElement(Namespace = "http://yourcompany.org/schemas/ns/child")]
public BaseClass BaseTest2 = new ChildNS.DerivedClass1();
public BaseClass[] BaseArray1 = {new BaseClass(), new DerivedClass1()};
[XmlArrayItem(typeof(BaseClass), IsNullable = true),
XmlArrayItem(typeof(DerivedClass1), IsNullable = true),
XmlArrayItem(typeof(DerivedClass2), IsNullable = true)]
public BaseClass[] BaseArray2 =
{
new BaseClass(), new DerivedClass1(),
null, new DerivedClass2()
};
[XmlArrayItem(typeof(BaseClass), IsNullable = true)]
public BaseClass[] BaseArray3 =
{
new BaseClass(),
new DerivedClass1(), null, new DerivedClass2()
};
[XmlArrayItem(typeof(BaseClass))]
public List<BaseClass> BaseList = new List<BaseClass> { new BaseClass(), new DerivedClass1() };
[XmlElement(IsNullable = true)]
public object NullObject1 = null;
public object NullObject2 = null;
//public IEnumerable BaseListEnumerable = new List<BaseClass> { new BaseClass(), new DerivedClass1() };
}
public class BaseClass
{
[XmlAttribute("value1", Namespace = "http://yourcompany.org/schemas/ns")]
public int Value1;
[XmlAttribute("value2")]
public int Value2;
[XmlAttribute("value3", Namespace = "http://yourcompany.org/schemas/ns")]
public int Value3;
}
public class DerivedClass1 : BaseClass
{
[XmlAttribute("value4", Namespace = "http://yourcompany.org/schemas/ns")]
public int Value4;
}
public class DerivedClass2 : BaseClass
{
[XmlAttribute("value4", Namespace = "http://yourcompany.org/schemas/ns")]
public int Value4;
}
namespace ChildNS
{
//为类型强制指定 XML 名称,以及命名空间,以避免命名冲突。
[XmlType("ChildDerivedClass", Namespace = "http://yourcompany.org/schemas/ns/child")]
public class DerivedClass1 : BaseClass
{
public int Value5;
}
}
}
运行结果如下
<?xml version="1.0" encoding="utf-16"?>
<TestClass xmlns:ns="http://yourcompany.org/schemas/ns" xmlns:nsc="http://yourcompany.org/schemas/ns/child" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<BaseTest ns:value1="0" value2="0" ns:value3="0" />
<BaseTest1 xsi:type="DerivedClass1" ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
<nsc:BaseTest2 xsi:type="nsc:ChildDerivedClass" ns:value1="0" value2="0" ns:value3="0">
<nsc:Value5>0</nsc:Value5>
</nsc:BaseTest2>
<BaseArray1>
<BaseClass ns:value1="0" value2="0" ns:value3="0" />
<BaseClass xsi:type="DerivedClass1" ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
</BaseArray1>
<BaseArray2>
<BaseClass ns:value1="0" value2="0" ns:value3="0" />
<DerivedClass1 ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
<DerivedClass2 ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
</BaseArray2>
<BaseArray3>
<BaseClass ns:value1="0" value2="0" ns:value3="0" />
<BaseClass xsi:type="DerivedClass1" ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
<BaseClass xsi:nil="true" />
<BaseClass xsi:type="DerivedClass2" ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
</BaseArray3>
<BaseList>
<BaseClass ns:value1="0" value2="0" ns:value3="0" />
<BaseClass xsi:type="DerivedClass1" ns:value1="0" value2="0" ns:value3="0" ns:value4="0" />
</BaseList>
<NullObject1 xsi:nil="true" />
</TestClass>
可以看出,
- 在 `XmlArrayItem(Attribute)`、`XmlElement` 等相关特性中指定 IsNullable = true 可以使得当前为 null / Nothing 的元素在序列化时产生一个包含 xsi:nil=”true” 特性的 XML 元素。
- 在特性中指定元素的命名空间时,应当指定命名空间的 URI,尽管可以稍后在 `XmlSerializerNamespaces` 中为这些 URI 指定对应的命名空间前缀。
- 需要序列化派生类时,总是 需要通过 XmlInclude 特性,或者通过 `XmlSerializer` 的构造函数显式声明序列化过程中可能用到的派生类。
- 数组的序列化:可以通过 `XmlArrayItem` 特性声明数组中可能包含的派生类类型。这些类型在序列化时会使用与之对应的元素名。如果存在未在 `XmlArrayItem` 中声明的派生类,而其基类在 `XmlArrayItem` 中声明过,则会使用基类对应的元素名,外加 `xsi:type` 特性声明实际派生类的类型。(关于这一点,可以参阅另一篇文章:MSDN中“(使用 XmlArrayItemAttribute 限定)序列化派生类”一节中的示例可能与实际有出入)
- 我该滚去修改以前的代码了。