LINQ to XML实现XML文档的增删改查

梦里梦外; 2021-09-10 04:58 311阅读 0赞

**1、实例中的XML文档（Books.xml）**

<?xml version="1.0" encoding="utf-8"?>
    <bookstore>
      <book id="1" category="CHILDREN">
        <title>Harry Potter</title>
        <author>J K. Rowling</author>
        <publishDate>2005-08-15</publishDate>
        <price>29.99</price>
      </book>
      <book id="2" category="WEB">
        <title>Learning XML</title>
        <author>Erik T. Ray</author>
        <publishDate>2003-10-18</publishDate>
        <price>39.95</price>
      </book>
      <book id="3" category="WEB">
        <title>XQuery Kick Start</title>
        <author>James McGovern</author>
        <publishDate>2005-06-25</publishDate>
        <price>49.99</price>
      </book>
    </bookstore>

**2、 创建图书信息实体类（BookInfo.cs）**

/// <summary>
    /// 图书信息实体类
    /// </summary>
    public class BookInfo
    {
        public int BookId { set; get; }             //图书ID
        public string Title { set; get; }           //图书名称
        public string Category { set; get; }        //图书分类
        public string Author { set; get; }          //图书作者
        public DateTime PublishDate { set; get; }   //出版时间
        public Double Price { set; get; }           //销售价格
    }

**3、 创建图书信息业务逻辑类（BookInfoBLL.cs）**

using System.Linq;
    using System.Xml.Linq;

public class BookInfoBLL
    {
        private string _basePath = AppDomain.CurrentDomain.SetupInformation.ApplicationBase + @"/xml/Books.xml";  //XML文件路径 
    
        /// <summary>
        /// 创建图书XML文档（创建）
        /// </summary>
        public void CreateBookXml()
        { 
            //获取图书列表
            List<BookInfo> bookList = GetBookList();
            //创建XML文档
            XDocument bookDoc = new XDocument();
            //创建声明对象
            XDeclaration xDeclaration = new XDeclaration("1.0", "utf-8", "yes");
            bookDoc.Declaration = xDeclaration;    //指定XML声明对象
            //创建bookstore节点
            XElement xElement = new XElement("bookstore");
            foreach (BookInfo book in bookList)
            {
                //创建book节点
                XElement bookXml = new XElement("book");
                //添加属性
                bookXml.Add(new XAttribute("id", book.BookId));
                bookXml.Add(new XAttribute("category", book.Category));
                //添加子节点
                bookXml.Add(new XElement("title", book.Title));
                bookXml.Add(new XElement("author", book.Author));
                bookXml.Add(new XElement("publishDate", book.PublishDate.ToString("yyyy-MM-dd")));
                bookXml.Add(new XElement("price", book.Price));
                //将book节点添加到bookstore节点中
                xElement.Add(bookXml);
            }
            //保存文件
            bookDoc.Add(xElement);
            bookDoc.Save(_basePath);
        }
    
        /// <summary>  
        /// 获取图书列表(查询)  
        /// </summary>  
        /// <param name="param">参数条件</param>  
        /// <returns>图书列表</returns> 
        public List<BookInfo> GetBookInfoList(BookInfo param)
        {
            List<BookInfo> bookList = new List<BookInfo>();
            XElement xml = XElement.Load(_basePath);
    
            var bookVar = xml.Descendants("book");   //默认查询所有图书
            if (param.BookId != 0) //根据图书ID查询  
            {
                bookVar = xml.Descendants("book").Where(a => a.Attribute("id").Value == param.BookId.ToString());
            }  
            else if (!String.IsNullOrEmpty(param.Category)) //根据图书类别查询  
            {
                bookVar = xml.Descendants("book").Where(a => a.Attribute("category").Value == param.Category);
            }  
            else if (!String.IsNullOrEmpty(param.Title)) //根据图书名称查询  
            {
                bookVar = xml.Descendants("book").Where(a => a.Element("title").Value == param.Title);
            }
    
            bookList = (from book in bookVar
                        select new BookInfo
                        {
                            BookId = int.Parse(book.Attribute("id").Value),
                            Category = book.Attribute("category").Value,
                            Title = book.Element("title").Value,
                            Author = book.Element("author").Value,
                            PublishDate = DateTime.Parse(book.Element("publishDate").Value),
                            Price = double.Parse(book.Element("price").Value)
                        }).ToList();
            return bookList;
        }
    
        /// <summary>  
        /// 增加图书信息（新增）  
        /// </summary>  
        /// <param name="param"></param>  
        /// <returns></returns>  
        public bool AddBookInfo(BookInfo param)
        {
            XElement xml = XElement.Load(_basePath);
            //创建book节点
            XElement bookXml = new XElement("book");
            //添加属性
            bookXml.Add(new XAttribute("id", param.BookId));
            bookXml.Add(new XAttribute("category", param.Category));
            //添加子节点
            bookXml.Add(new XElement("title", param.Title));
            bookXml.Add(new XElement("author", param.Author));
            bookXml.Add(new XElement("publishDate", param.PublishDate.ToString("yyyy-MM-dd")));
            bookXml.Add(new XElement("price", param.Price));
            xml.Add(bookXml);
            //保存
            xml.Save(_basePath);
            return true;
        }
    
        /// <summary>  
        /// 修改图书信息（修改）  
        /// </summary>  
        /// <param name="param"></param>  
        /// <returns></returns>  
        public bool EditBookInfo(BookInfo param)
        {
            bool result = false;
            if (param.BookId > 0)
            {
                //根据BookId找到要修改的图书XML
                XElement xml = XElement.Load(_basePath);
                XElement bookXml = (from db in xml.Descendants("book") where db.Attribute("id").Value == param.BookId.ToString() select db).Single();
                //修改属性
                bookXml.SetAttributeValue("category", param.Category);
                //修改子节点
                bookXml.SetElementValue("title", param.Title);
                bookXml.SetElementValue("author", param.Author);
                bookXml.SetElementValue("publishDate", param.PublishDate.ToString("yyyy-MM-dd"));
                bookXml.SetElementValue("price", param.Price);
                //保存
                xml.Save(_basePath);
                result = true;
            }
            return result;
        }
    
        /// <summary>  
        /// 删除图书信息（删除）  
        /// </summary>  
        /// <param name="param"></param>  
        /// <returns></returns>  
        public bool DeleteBookInfo(BookInfo param)
        {
            bool result = false;
            if (param.BookId > 0)
            {
                //根据BookId找到要删除的图书XML
                XElement xml = XElement.Load(_basePath);
                XElement bookXml = (from db in xml.Descendants("book") where db.Attribute("id").Value == param.BookId.ToString() select db).Single();
                bookXml.Remove();
                //保存
                xml.Save(_basePath);
                result = true;
            }
            return result;
        }
    
        /// <summary>
        /// 获取图书列表
        /// </summary>
        /// <returns></returns>
        public List<BookInfo> GetBookList()
        {
            List<BookInfo> bookList = new List<BookInfo>();
            //创建图书1
            BookInfo book1 = new BookInfo() { 
                BookId = 1,
                Category = "CHILDREN",
                Title = "Harry Potter",
                Author = "J K. Rowling",
                PublishDate = new DateTime(2005,08,15),
                Price = 29.99
            };
            bookList.Add(book1);
            //创建图书2
            BookInfo book2 = new BookInfo()
            {
                BookId = 2,
                Category = "WEB",
                Title = "Learning XML",
                Author = "Erik T. Ray",
                PublishDate = new DateTime(2003,10,18),
                Price = 39.95
            };
            bookList.Add(book2);
            //创建图书3
            BookInfo book3 = new BookInfo()
            {
                BookId = 3,
                Category = "WEB",
                Title = "XQuery Kick Start",
                Author = "James McGovern",
                PublishDate = new DateTime(2005,6,25),
                Price = 49.99
            };
            bookList.Add(book3);
            return bookList;
        }
    }