三种读取XML方法的比较.docx

使用XMLReader、XMLDocument和DataSet读取xml文件及效率 在 .NET 开发中经常需要读取和操作XML文件，例如：操作配置文件（web.config和app.config）、读取业务设置的xml文件等。以前都喜欢用DataSet直接读取或写入xml，当文件小的时候，读取效率还能接受，但是当文件很大的时候，读取就变得很慢了。闲暇之于就对 XMLReader 、 XMLDocument和DataSet 读取XML文件进行简单总结，对效率进行简单比较。1、XMLReader 读取XML文件 XMLReader 提供对 XML 数据进行快速、非缓存、只进访问的读取器。XMLReader 只能读取xml文件，需要我们自己控制怎样获取相应的xml节点的信息，适合于读取很大的xml文件。XMLReader 有一个类型为XmlNodeType的NodeType只读属性，通过它可以知道当前节点类型，以及根据节点类型和具体需求获取相应节点的信息。更详细的信息可以到微软技术资源库进行查询和了解。XMLReader读取XML文件方式如下： 1: static ListDictionary XMLReaderTest(string xmlPath) 2: 3: ListDictionary entityInfo = new ListDictionary(); 4: using (XmlReader reader = new XmlTextReader(xmlPath) 5: 6: Dictionary xmlValue = null; 7: string key = string.Empty; 8: while (reader.Read() 9: 10: switch (reader.NodeType) 11: 12: case XmlNodeType.Element: 13: if (string.Compare(reader.LocalName, BE_WorkStation_ACInstance, StringComparison.OrdinalIgnoreCase) = 0) 14: 15: xmlValue = new Dictionary(); 16: 17: else 18: 19: if (string.Compare(reader.LocalName, EntitySchema, StringComparison.OrdinalIgnoreCase) != 0) 20: 21: key = reader.LocalName; 22: 23: 24: break; 25: case XmlNodeType.EndElement: 26: if (string.Compare(reader.LocalName, BE_WorkStation_ACInstance, StringComparison.OrdinalIgnoreCase) = 0) 27: 28: if (xmlValue != null) 29: 30: entityInfo.Add(xmlValue); 31: xmlValue = null; 32: 33: 34: break; 35: case XmlNodeType.Text: 36: if (xmlValue != null) 37: 38: xmlValue.Add(key, reader.Value); 39: 40: break; 41: default: 42: break; 43: 44: 45: 46: return entityInfo; 47: 2、XMLDocument读取XML文件 XMLDocument 表示XML文档在内存中的树形结构，它提供像js操作html文档一样的方式操作XML文档。在读取单个小XML文件时效率比较高。XMLDocument 读取XML文件方式如下： 1: static ListDictionary XMLDocumentTest(string xmlPath) 2: 3: ListDictionary entityInfo = new ListDictionary(); 4: using (XmlReader reader = new XmlTextReader(xmlPath) 5: 6: XmlDocument doc = new XmlDocument(); 7: doc.Load(reader); 8: XmlNodeList nodeList = doc.ChildNodes; 9: foreach (XmlNode node in nodeList) 10: 11: var xmlValue = new Dictionary(); 12: foreach (XmlNode child in node.ChildNodes) 13: 14: xmlValuechild.LocalName = child.InnerText; 15: 16: entityInfo.Add(xmlValue); 17: 18: 19: return entityInfo; 20: 3、DataSet 读取XML文件 DataSet 类型提供了一个ReadXml 方法，它将XML架构和数据读入DataSet中。DataSet 在读取 XML 文件时效率很低。DataSet 读取XML文件方式如下： 1: static ListDictionary DataSetTest(string xmlPath) 2: 3: ListDictionary entityInfo = new ListDictionary(); 4: DataSet ds = new DataSet(); 5: /读取XML文件架构 6: using (XmlReader reader = new XmlTextReader(xmlPath) 7: 8: ds.ReadXmlSchema(reader); 9: 10: foreach (DataTable dt in ds.Tables) 11: 12: dt.BeginLoadData(); 13: 14: using (XmlReader reader = new XmlTextReader(xmlPath) 15: 16: ds.ReadXml(reader); 17: 18: foreach (DataTable dt in ds.Tables) 19: 20: dt.EndLoadData(); 21: 22: if (ds.Tables.Count 0) 23: 24: DataTable dt = ds.Tables0; 25: foreach (DataRow row in dt.Rows) 26: 27: var xmlValue = new Dictionary(); 28: foreach (DataColumn col in dt.Columns) 29: 30: xmlValuecol.ColumnName = row.Field(col); 31: 32: entityInfo.Add(xmlValue); 33: 34: 35: return entityInfo; 36: 读取的xml文件片段： 1: 2: 3: 4: 5: MS_ACInstanceOID 6: 主键 7: 45 8: 500 9: 0 10: 选择 11: false 12: true 13: 14: 0 15: true 16: 17: 18: 19: 选择列 20: false 21: MS_ACInstance.MS_ACInstanceOID as MS_ACInstanceOID 22: true 23: 24: true 25: true 26: 27: 28: 29: 30: false 31: 32: 33: 34: 35: sys_rank 36: 排序标识 37: 2 38: 500 39: 0 40: 选择 41: false 42: true 43: 44: 0 45: true 46: 47: 48: 49: 选择列 50: false 51: MS_ACInstance.BASE_Rank as sys_rank 52: true 53: BASE_Rank 54: true 55: true 56: 57: 58: 59: 60