将数据导出到xml，并从xml导入数据

将数据导出到xml，并从xml导入数据

xml本质上是数据，是另一种格式的数据。而ADO.NET就是用来处理数据的。因此通过DataSet可以非常方便的处理xml。下面这段程序对如下问题做出了解答：

？

生成的XML没有表之间的关系怎么办？

怎样把列数据作为子元素?(在利用数据集得到XML时)

怎样把列数据作为属性?(在利用数据集得到XML时)

怎样利用数据集形成XML文件?

怎样设置xml的namespace和prefix？

怎样控制控制文本的格式？

怎样把XML文件里的数据读入数据集?

怎样利用XML文件传递数据集架构?

怎样利用XML文件在不同数据集之间传递更改？

using System;

using System.Data;

using System.Data.OleDb;

using General.ADONET;

using General.ADONET.OLEDBClient;

using System.IO;

using System.Xml;

namespace PlayXML

{

///<summary>

/// PlayXML 的摘要说明。

///</summary>

public class XMLPlayer

{

public XMLPlayer()

{

//

// TODO: 在此处添加构造函数逻辑

//

}

private Adapter adptEmp;

private Adapter adptDept;

private OleDbConnection conn;

private DataSet dsHR;

//初始化数据集

public voidInitDataSet()

{

string strConn = "Provider = Microsoft.Jet.OLEDB.4.0;";

strConn += "Data Source = E:\\everyday\\VS\\HELPREN\\hr.mdb;";

this.conn = new OleDbConnection(strConn);

dsHR = new DataSet();

this.adptEmp =

new Adapter(this.conn, dsHR, "employees");

this.adptDept =

new Adapter(this.conn, dsHR, "departments");

this.adptDept.Fill();

this.adptEmp.Fill();

DataTable dtDept = this.dsHR.Tables["departments"];

DataTable dtEmp = this.dsHR.Tables["employees"];

DataColumn colParent = dtDept.Columns["dept_id"];

DataColumn colChild = dtEmp.Columns["emp_department"];

dsHR.Relations.Add(

"departments_employees",

colParent, colChild);//关系

}

//怎样从DataSet得到xml？

public void GetXml()

{

Console.WriteLine(

this.dsHR.GetXml()//这个方法就是从DataSet得到xml

);

}

//生成的XML没有表之间的关系怎么办？

public void GetXmlWithRalation()

{

//指定DataRelation在DataSet中进行嵌套

//使xml序列化生成关系

this.dsHR.Relations["departments_employees"].Nested = true;

Console.WriteLine(

this.dsHR.GetXml()//这个方法就是从DataSet得到xml

);

}

//怎样把列数据作为子元素?(在利用数据集得到XML时)

public void GetSubElements()

{

DataTable dtEmp = this.dsHR.Tables["employees"];

foreach(DataColumn col in dtEmp.Columns)

{

//列的ColumnMapping属性设置为MappingType.Element就可以了

col.ColumnMapping = MappingType.Element;

}

DataTable dtDept = this.dsHR.Tables["departments"];

foreach(DataColumn col in dtDept.Columns)

{

//列的ColumnMapping属性设置为MappingType.Element就可以了

col.ColumnMapping = MappingType.Element;

}

this.dsHR.GetXml();

}

//怎样把列数据作为属性?(在利用数据集得到XML时)

public void GetAttributes()

{

DataTable dtEmp = this.dsHR.Tables["employees"];

foreach(DataColumn col in dtEmp.Columns)

{

//列的ColumnMapping属性设置为MappingType.Attribute就可以了

col.ColumnMapping = MappingType.Attribute;

}

DataTable dtDept = this.dsHR.Tables["departments"];

foreach(DataColumn col in dtDept.Columns)

{

//列的ColumnMapping属性设置为MappingType.Attribute就可以了

col.ColumnMapping = MappingType.Attribute;

}

this.dsHR.GetXml();

}

//怎样利用数据集形成XML文件?

public void WriteXml()

{

//怎样设置xml的namespace和prefix？

this.dsHR.Namespace = "ADONET";

this.dsHR.Prefix = "an";

this.dsHR.WriteXml("test.xml", XmlWriteMode.WriteSchema);

//怎样控制控制文本的格式？

StreamWriter sw = new StreamWriter("test2.xml");

XmlTextWriter xmlWriter = new XmlTextWriter(sw);

xmlWriter.Formatting = Formatting.Indented;

xmlWriter.Indentation = 10;

this.dsHR.WriteXml(xmlWriter);

xmlWriter.Close();

}

//怎样把XML文件里的数据读入数据集?

public void ReadXml()

{

DataSet dsNew = new DataSet();

dsNew.ReadXml("test.xml");

Console.WriteLine(dsNew.GetXml());

}

//怎样利用XML文件传递数据集架构?

public void TransmitSchema()

{

StreamWriter sw = new StreamWriter("test.xsd");

XmlTextWriter xmlWriter = new XmlTextWriter(sw);

this.dsHR.WriteXmlSchema(xmlWriter);

xmlWriter.Close();

DataSet dsNew = new DataSet();

dsNew.ReadXmlSchema("test.xsd");

foreach(DataTable dt in dsNew.Tables)

{

Console.WriteLine(dt.TableName);

foreach(DataColumn dc in dt.Columns)

{

Console.WriteLine(" " + dc.ColumnName);

}

}

}

//怎样利用XML文件在不同数据集之间传递更改？

public void PlayDiffGram()

{

//为两个datatable设置主键

DataTable dtEmp = this.dsHR.Tables["employees"];

DataTable dtDept = this.dsHR.Tables["departments"];

dtEmp.PrimaryKey = new DataColumn[]

{dtEmp.Columns["emp_id"]};

dtDept.PrimaryKey = new DataColumn[]

{dtDept.Columns["dept_id"]};

//把数据集写到xml文件

StreamWriter sw = new StreamWriter("test.xml");

XmlTextWriter xmlWriter = new XmlTextWriter(sw);

this.dsHR.WriteXml(xmlWriter, XmlWriteMode.WriteSchema);

sw.Close();

//从xml文件读入数据到一个新的数据集里

DataSet dsNew = new DataSet();

dsNew.ReadXml("test.xml", XmlReadMode.ReadSchema);

dsNew.AcceptChanges();

//修改值

this.dsHR.Tables["employees"].Rows[0]["emp_name"] = "aaaaa";

dsNew.Tables["employees"].Rows[0]["emp_name"] = "ccccc";

//把新数据集里的数据输出到xml文件

Stream newStream = new MemoryStream() as Stream;

XmlTextWriter xmlNewWriter =

new XmlTextWriter(newStream, null);

xmlNewWriter.Formatting = Formatting.Indented;

dsNew.GetChanges().WriteXml(xmlNewWriter, XmlWriteMode.DiffGram);

//显示现在xml文件的内容

newStream.Position = 0;

StreamReader rdr = new StreamReader(newStream);

Console.WriteLine(rdr.ReadToEnd());

newStream.Position = 0;

//把现在的xml文件的内容读到原先的那个数据集

this.dsHR.ReadXml(newStream, XmlReadMode.DiffGram);

}

}

}

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