.Net程序执行时，对象都驻留在内存中；内存中的对象如果需要传递给其他系统使用；或者在关机时需要保存下来以便下次再次启动程序使用就需要序列化和反序列化。

这两个回答都是对的。

好了，现在我们来具体的看看XmlSerializer类的含义吧：

XmlSerializer类：将对象序列化到 XML 文档中和从 XML 文档中反序列化对象。XmlSerializer 使您得以控制如何将对象编码到 XML 中。

XML 序列化是将对象的公共属性 (Property)（如Student的Name属性）和字段转换为序列格式（这里是指 XML）以便存储或传输的过程。反序列化则是从 XML 输出中重新创建原始状态的对象。因此，可以将序列化视为将对象的状态保存到流或缓冲区的方法。例如，ASP.NET 使用 XmlSerializer 类对 XML Web services 消息进行编码。

范围：本文只介绍xml序列化，其实序列化可以是二进制的序列化，也可以是其他格式的序列化

看一段最简单的Xml序列化代码：

class Program
{static void Main(string[] args){int i = 10;//声明Xml序列化对象实例serializerXmlSerializer serializer = new XmlSerializer(typeof(int));//执行序列化并将序列化结果输出到控制台
        serializer.Serialize(Console.Out, i);Console.Read();}
}

<?xml version="1.0" encoding="gb2312"?>
<int>10</int>

static void Main(string[] args)
{using (StringReader rdr = new StringReader(@"<?xml version=""1.0"" encoding=""gb2312""?>
<int>10</int>")){//声明序列化对象实例serializer XmlSerializer serializer = new XmlSerializer(typeof(int));//反序列化，并将反序列化结果值赋给变量iint i = (int)serializer.Deserialize(rdr);//输出反序列化结果Console.WriteLine("i = " + i);Console.Read();}
}

　　public class People{//XmlAttribute:指定XmlSerializer将该类成员序列化为XML属性
        [XmlAttribute]public string Name { get; set; }[XmlAttribute]public int Age { get; set; }}[XmlRoot]public class Student : People{//定义SClass属性的序列化为Student节点的属性        [XmlElement]public string SClass { get; set; }[XmlElement]public int Number { get; set; }}

    Student stu = new Student() { Age = 12, Number = 23, Name = "张三", SClass = "高一（2）班" };XmlSerializer ser = new XmlSerializer(typeof(Student));StringWriter writer = new StringWriter();ser.Serialize(writer,stu);MessageBox.Show(writer.ToString());

    //将Xml反序列为Student对象StringReader reader = new StringReader(writer.ToString());
    //Deserialize反序列化指定TextReader包含的Xml文档，当然，不仅仅可以是TextReader，还可以是Stream等等，具体看起构造函数参数即可知道Student stu2= (Student)ser.Deserialize(reader);

    List<Student> stuList = new List<Student>();stuList.Add(new Student() { Age = 10, Number = 1, Name = "Tom", SClass = "Class One" });stuList.Add(new Student() { Age = 11, Number = 2, Name = "Jay", SClass = "Class Two" });stuList.Add(new Student() { Age = 12, Number = 3, Name = "Pet", SClass = "Class One" });stuList.Add(new Student() { Age = 13, Number = 4, Name = "May", SClass = "Class Three" });stuList.Add(new Student() { Age = 14, Number = 5, Name = "Soy", SClass = "Class Two" });//序列化XmlSerializer ser = new XmlSerializer(typeof(List<Student>));StringWriter writer = new StringWriter();
    //将学生列表序列化为Xml数据
    ser.Serialize(writer, stuList);    //反序列化
    //要先将构造StringReader，作为Deserialize()的初始化参数StringReader reader = new StringReader(writer.ToString());//别忘了从Object到List<Student>，否则会报错。。List<Student> stuList2 = (List<Student>)ser.Deserialize(reader);

    Dictionary<string, int> dic = new Dictionary<string, int>();dic.Add("第一",1);dic.Add("第二", 2);dic.Add("第三", 3);dic.Add("第四", 4);List<DictionaryList> dicList = new List<DictionaryList>();
    foreach (var a in dic){DictionaryList dicl = new DictionaryList() {  Name=a.Key, Value=a.Value};dicList.Add(dicl);}
    //序列化XmlSerializer ser = new XmlSerializer(typeof(List<DictionaryList>));StringWriter writer = new StringWriter();
    //序列化为Xml数据
    ser.Serialize(writer, dicList);MessageBox.Show(writer.ToString());    //反序列化StringReader reader = new StringReader(writer.ToString());            List<DictionaryList> stuList2 = (List<DictionaryList>)ser.Deserialize(reader);

    [XmlRoot("cats")]public class CatCollection{[XmlArray("items"), XmlArrayItem("item")]public Cat[] Cats { get; set; }}//[XmlRoot("cat")] 加不加都无所谓的。public class Cat{//定义Color属性的序列化为cat节点的属性[XmlAttribute("color")]public string Color { get; set; }//要求不序列化Speed属性
        [XmlIgnore]public int Speed { get; set; }//设置Saying属性序列化为Xml子元素[XmlElement("saying")]public string Saying { get; set; }}

   //声明一个猫咪对象
   var cWhite = new Cat { Color = "White", Speed = 10, Saying = "White or black,  so long as the cat can catch mice,  it is a good cat" };
   var cBlack = new Cat { Color = "Black", Speed = 10, Saying = "White or black,  so long as the cat can catch mice,  it is a good cat" };CatCollection cc = new CatCollection { Cats = new Cat[] { cWhite, cBlack } };   //序列化这个对象XmlSerializer serializer = new XmlSerializer(typeof(CatCollection));StringWriter writer = new StringWriter();serializer.Serialize(writer,cc);MessageBox.Show(writer.ToString());

1.通过XmlDocument读写Xml文档

2.使用XmlReader读Xml，使用XmlWriter写Xml

3.使用Linq to xml存取XML

4.通过XmlScheme定义固定格式xml文档

5.Xml序列化或者反序列化类

6.通过XPath查找Xml节点

7.通过Xslt转化Xml格式

补充：EncodeHelper类，只不过将上述我们序列化和反序列化进行封装而已，很容易理解

　

参考博客：http://www.cnblogs.com/yukaizhao/archive/2011/07/22/xml-serialization.html