C#語法小知識(十六)序列化與反序列化(XML)
阿新 • • 發佈:2019-01-31
C#提供了兩類序列化與反序列化的手段,一種是XmlSerializer(名稱空間System.Xml.Serialization),另一種我們會在後續文章中介紹(參考C#語法小知識(十七)序列化與反序列化(Binary))。
首先我們定義一個Book類,我們要在程式中對它進行序列化和反序列化:
public class Book { public string title; public int No; public Book(string title_, int no_) { title = title_; No = no_; } public Book() { } }
實現序列化和反序列化的方法:
public void WriteXML() { Book book = new Book("xml", 1); XmlSerializer writer = new XmlSerializer(typeof(Book)); System.IO.StreamWriter file = new System.IO.StreamWriter(@"xml.xml"); writer.Serialize(file, book); file.Close(); } public void ReadXML() { XmlSerializer reader = new XmlSerializer(typeof(Book)); System.IO.StreamReader file = new System.IO.StreamReader(@"xml.xml"); Book book = reader.Deserialize(file) as Book; Console.WriteLine(book.title); Console.WriteLine(book.No); file.Close(); }
使用:
WriteXML ();
ReadXML ();
列印:
xml
1
如果某些變數不需要序列化,可以為這個變數增加特性XmlIgnore(關於特性參考C#語法小知識(七)特性)。
例如我們在為No變數增加特性:
[XmlIgnore]
public int No;
那麼打印出來的結果就是:
xml
0
xml序列化非常易用且好用,而且我們可以看到序列化之後的檔案:
<?xml version="1.0" encoding="utf-8"?> <Book xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <title>xml</title> </Book>
但是如果要在一個檔案中序列化多個不同類的物件,那麼就會麻煩一點。
例如我們定義了一個Album類:
public class Album
{
public string owner;
public int count;
public Album(string owner_, int count_)
{
owner = owner_;
count = count_;
}
public Album()
{
}
}
為了一個檔案中同時序列化Book和Album的例項,我們就需要再額外定義一個包含Book和Album變數的型別:
public class Shelf
{
public Book book;
public Album album;
}
定義序列化和反序列化方法:
public void WriteShelfXML()
{
Shelf shelf = new Shelf ();
shelf.book = new Book ("shelf_xml", 2);
shelf.album = new Album ("Jessica", 27);
XmlSerializer writer = new XmlSerializer(typeof(Shelf));
System.IO.StreamWriter file = new System.IO.StreamWriter(@"shelf_xml.xml");
writer.Serialize(file, shelf);
file.Close();
}
public void ReadShelfXML()
{
XmlSerializer reader = new XmlSerializer(typeof(Shelf));
System.IO.StreamReader file = new System.IO.StreamReader(@"shelf_xml.xml");
Shelf shelf = reader.Deserialize(file) as Shelf;
Console.WriteLine(shelf.book.title);
Console.WriteLine(shelf.book.No);
Console.WriteLine(shelf.album.owner);
Console.WriteLine(shelf.album.count);
file.Close();
}
xml檔案:
<?xml version="1.0" encoding="utf-8"?>
<Shelf xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<book>
<title>shelf_xml</title>
</book>
<album>
<owner>Jessica</owner>
</album>
</Shelf>