DataSet.ReadXml 方法

public:
 System::Data::XmlReadMode ReadXml(System::Xml::XmlReader ^ reader, System::Data::XmlReadMode mode);

public System.Data.XmlReadMode ReadXml (System.Xml.XmlReader reader, System.Data.XmlReadMode mode);

member this.ReadXml : System.Xml.XmlReader * System.Data.XmlReadMode -> System.Data.XmlReadMode

Public Function ReadXml (reader As XmlReader, mode As XmlReadMode) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果的 XML 架构 DataSet 包含 targetNamespace ，则数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes a targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::String ^ fileName, System::Data::XmlReadMode mode);

public System.Data.XmlReadMode ReadXml (string fileName, System.Data.XmlReadMode mode);

member this.ReadXml : string * System.Data.XmlReadMode -> System.Data.XmlReadMode

Public Function ReadXml (fileName As String, mode As XmlReadMode) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

例外

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果的 XML 架构 DataSet 包含 targetNamespace ，则数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes a targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::IO::Stream ^ stream, System::Data::XmlReadMode mode);

public System.Data.XmlReadMode ReadXml (System.IO.Stream stream, System.Data.XmlReadMode mode);

member this.ReadXml : System.IO.Stream * System.Data.XmlReadMode -> System.Data.XmlReadMode

Public Function ReadXml (stream As Stream, mode As XmlReadMode) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

对于和方法也是如此 WriteXml WriteXmlSchema 。The same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果包含的 XML 架构 DataSet ，则 targetNamespace 数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::IO::TextReader ^ reader, System::Data::XmlReadMode mode);

public System.Data.XmlReadMode ReadXml (System.IO.TextReader reader, System.Data.XmlReadMode mode);

member this.ReadXml : System.IO.TextReader * System.Data.XmlReadMode -> System.Data.XmlReadMode

Public Function ReadXml (reader As TextReader, mode As XmlReadMode) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果包含的 XML 架构 DataSet ，则 targetNamespace 数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::String ^ fileName);

public System.Data.XmlReadMode ReadXml (string fileName);

member this.ReadXml : string -> System.Data.XmlReadMode

Public Function ReadXml (fileName As String) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

例外

示例

下面的示例首先创建一个简单 DataSet 的，其中包含一个 DataTable 、两个列和10个行。The following example first creates a simple DataSet with one DataTable, two columns, and ten rows. DataSet通过调用方法将架构和数据写入磁盘 WriteXml 。The DataSet schema and data are written to disk by invoking the WriteXml method. 将创建第二个 DataSet ，并 ReadXml 使用方法来填充架构和数据。A second DataSet is created and the ReadXml method is used to fill it with schema and data.

private void DemonstrateReadWriteXMLDocumentWithStreamReader()
{
    // Create a DataSet with one table and two columns.
    DataSet OriginalDataSet = new DataSet("dataSet");
    OriginalDataSet.Namespace= "NetFrameWork";
    DataTable table = new DataTable("table");
    DataColumn idColumn = new DataColumn("id",
        Type.GetType("System.Int32"));
    idColumn.AutoIncrement= true;

    DataColumn itemColumn = new DataColumn("item");
    table.Columns.Add(idColumn);
    table.Columns.Add(itemColumn);
    OriginalDataSet.Tables.Add(table);

    // Add ten rows.
    DataRow newRow;
    for(int i = 0; i < 10; i++)
    {
        newRow = table.NewRow();
        newRow["item"]= "item " + i;
        table.Rows.Add(newRow);
    }
    OriginalDataSet.AcceptChanges();

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(OriginalDataSet, "Original DataSet");

    // Write the schema and data to an XML file.
    string xmlFilename = "XmlDocument.xml";

    // Use WriteXml to write the document.
    OriginalDataSet.WriteXml(xmlFilename);

    // Dispose of the original DataSet.
    OriginalDataSet.Dispose();

    // Create a new DataSet.
    DataSet newDataSet = new DataSet("New DataSet");

    // Read the XML document into the DataSet.
    newDataSet.ReadXml(xmlFilename);

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(newDataSet,"New DataSet");
}

private void PrintValues(DataSet dataSet, string label)
{
    Console.WriteLine("\n" + label);
    foreach(DataTable table in dataSet.Tables)
    {
        Console.WriteLine("TableName: " + table.TableName);
        foreach(DataRow row in table.Rows)
        {
            foreach(DataColumn column in table.Columns)
            {
                Console.Write("\table " + row[column] );
            }
            Console.WriteLine();
        }
    }
}

Private Sub DemonstrateReadWriteXMLDocumentWithStreamReader()
    ' Create a DataSet with one table and two columns.
    Dim OriginalDataSet As New DataSet("dataSet")
    OriginalDataSet.Namespace = "NetFrameWork"
    Dim table As New DataTable("table")
    Dim idColumn As New DataColumn("id", _
        Type.GetType("System.Int32"))
    idColumn.AutoIncrement = True

    Dim itemColumn As New DataColumn("item")
    table.Columns.Add(idColumn)
    table.Columns.Add(itemColumn)
    OriginalDataSet.Tables.Add(table)

    ' Add ten rows.
    Dim newRow As DataRow
    Dim i As Integer
    For i = 0 To 9
        newRow = table.NewRow()
        newRow("item") = "item " & i.ToString()
        table.Rows.Add(newRow)
    Next i
    OriginalDataSet.AcceptChanges()

    ' Print out values of each table in the DataSet 
    ' using the function defined below.
    PrintValues(OriginalDataSet, "Original DataSet")

    ' Write the schema and data to an XML file.
    Dim xmlFilename As String = "XmlDocument.xml"

    ' Use WriteXml to write the document.
    OriginalDataSet.WriteXml(xmlFilename)

    ' Dispose of the original DataSet.
    OriginalDataSet.Dispose()

    ' Create a new DataSet.
    Dim newDataSet As New DataSet("New DataSet")

    ' Read the XML document into the DataSet.
    newDataSet.ReadXml(xmlFilename)

    ' Print out values of each table in the DataSet 
    ' using the function defined below.
    PrintValues(newDataSet, "New DataSet")
End Sub
    
Private Sub PrintValues(dataSet As DataSet, label As String)
    Console.WriteLine(ControlChars.Cr & label)
    Dim table As DataTable
    For Each table In  dataSet.Tables
        Console.WriteLine("TableName: " & table.TableName)
        Dim row As DataRow
        For Each row In  table.Rows
            Dim column As DataColumn
            For Each column In  table.Columns
                Console.Write(ControlChars.Tab & " " & _
                    row(column).ToString())
            Next column
            Console.WriteLine()
        Next row
    Next table
End Sub

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果的 XML 架构 DataSet 包含 targetNamespace ，则数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes a targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::IO::TextReader ^ reader);

public System.Data.XmlReadMode ReadXml (System.IO.TextReader reader);

member this.ReadXml : System.IO.TextReader -> System.Data.XmlReadMode

Public Function ReadXml (reader As TextReader) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

示例

下面的示例首先创建一个简单 DataSet 的，其中包含一个 DataTable 、两个列和10个行。The following example first creates a simple DataSet with one DataTable, two columns, and ten rows. DataSet通过调用方法将架构和数据写入磁盘 WriteXml 。The DataSet schema and data are written to disk by invoking the WriteXml method. 将创建第二个 DataSet ，并 ReadXml 使用方法来填充架构和数据。A second DataSet is created and the ReadXml method is used to fill it with schema and data.

private void DemonstrateReadWriteXMLDocumentWithFileStream()
{
    // Create a DataSet with one table and two columns.
    DataSet originalDataSet = new DataSet("dataSet");
    DataTable table = new DataTable("table");
    DataColumn idColumn = new DataColumn("id",
        Type.GetType("System.Int32"));
    idColumn.AutoIncrement= true;

    DataColumn itemColumn = new DataColumn("item");
    table.Columns.Add(idColumn);
    table.Columns.Add(itemColumn);
    originalDataSet.Tables.Add(table);
    // Add ten rows.

    DataRow newRow;
    for(int i = 0; i < 10; i++)
    {
        newRow = table.NewRow();
        newRow["item"]= "item " + i;
        table.Rows.Add(newRow);
    }
    originalDataSet.AcceptChanges();

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(originalDataSet, "Original DataSet");

    // Write the schema and data to XML file with FileStream.
    string xmlFilename = "XmlDocument.xml";
    System.IO.FileStream streamWrite = new System.IO.FileStream
        (xmlFilename, System.IO.FileMode.Create);

    // Use WriteXml to write the XML document.
    originalDataSet.WriteXml(streamWrite);

    // Close the FileStream.
    streamWrite.Close();

    // Dispose of the original DataSet.
    originalDataSet.Dispose();
    // Create a new DataSet.
    DataSet newDataSet = new DataSet("New DataSet");

    // Read the XML document back in.
    // Create new FileStream to read schema with.
    System.IO.FileStream streamRead = new System.IO.FileStream
        (xmlFilename,System.IO.FileMode.Open);
    newDataSet.ReadXml(streamRead);

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(newDataSet,"New DataSet");
}

private void PrintValues(DataSet dataSet, string label)
{
    Console.WriteLine("\n" + label);
    foreach(DataTable table in dataSet.Tables)
    {
        Console.WriteLine("TableName: " + table.TableName);
        foreach(DataRow row in table.Rows)
        {
            foreach(DataColumn column in table.Columns)
            {
                Console.Write("\table " + row[column] );
            }
            Console.WriteLine();
        }
    }
}

Private Sub DemonstrateReadWriteXMLDocumentWithFileStream()
    ' Create a DataSet with one table and two columns.
    Dim originalDataSet As New DataSet("dataSet")
    Dim table As New DataTable("table")
    Dim idColumn As New DataColumn("id", _
       Type.GetType("System.Int32"))
    idColumn.AutoIncrement = True

    Dim itemColumn As New DataColumn("item")
    table.Columns.Add(idColumn)
    table.Columns.Add(itemColumn)
    originalDataSet.Tables.Add(table)

    ' Add ten rows.
    Dim newRow As DataRow
    Dim i As Integer
    For i = 0 To 9
        newRow = table.NewRow()
        newRow("item") = "item " & i.ToString()
        table.Rows.Add(newRow)
    Next i
    originalDataSet.AcceptChanges()

    ' Print out values of each table in the DataSet 
    ' using the function defined below.
    PrintValues(originalDataSet, "Original DataSet")

    ' Write the schema and data to XML file with FileStream.
    Dim xmlFilename As String = "XmlDocument.xml"
    Dim streamWrite As New System.IO.FileStream _
       (xmlFilename, System.IO.FileMode.Create)

    ' Use WriteXml to write the XML document.
    originalDataSet.WriteXml(streamWrite)

    ' Close the FileStream.
    streamWrite.Close()
     
    ' Dispose of the original DataSet.
    originalDataSet.Dispose()
    ' Create a new DataSet.
    Dim newDataSet As New DataSet("New DataSet")
       
    ' Read the XML document back in. 
    ' Create new FileStream to read schema with.
    Dim streamRead As New System.IO.FileStream _
       (xmlFilename, System.IO.FileMode.Open)
     
    newDataSet.ReadXml(streamRead)
    ' Print out values of each table in the DataSet  
    ' using the function defined below.
    PrintValues(newDataSet, "New DataSet")
End Sub
   
Private Sub PrintValues(dataSet As DataSet, label As String)
    Console.WriteLine(ControlChars.Cr & label)
    Dim table As DataTable
    Dim row As DataRow
    Dim column As DataColumn
    For Each table In  dataSet.Tables
        Console.WriteLine("TableName: " & table.TableName)         
        For Each row In  table.Rows             
            For Each column In  table.Columns
                Console.Write(ControlChars.Tab & " " & _
                   row(column).ToString())
            Next column
            Console.WriteLine()
        Next row
    Next table
End Sub

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果包含的 XML 架构 DataSet ，则 targetNamespace 数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

继承自类的类 TextReader 包括 StreamReader 和 StringReader 类。Classes that inherit from the TextReader class include the StreamReader and StringReader classes.

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::IO::Stream ^ stream);

public System.Data.XmlReadMode ReadXml (System.IO.Stream stream);

member this.ReadXml : System.IO.Stream -> System.Data.XmlReadMode

Public Function ReadXml (stream As Stream) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

示例

下面的示例首先创建一个简单 DataSet 的，其中包含一个 DataTable 、两个列和10个行。The following example first creates a simple DataSet with one DataTable, two columns, and ten rows. DataSet通过调用方法将架构和数据写入磁盘 WriteXml 。The DataSet schema and data are written to disk by invoking the WriteXml method. 将创建第二个 DataSet ，并 ReadXml 使用方法来填充架构和数据。A second DataSet is created and the ReadXml method is used to fill it with schema and data.

private void DemonstrateReadWriteXMLDocumentWithFileStream()
{
    // Create a DataSet with one table and two columns.
    DataSet originalDataSet = new DataSet("dataSet");
    DataTable table = new DataTable("table");
    DataColumn idColumn = new DataColumn("id",
        Type.GetType("System.Int32"));
    idColumn.AutoIncrement= true;

    DataColumn itemColumn = new DataColumn("item");
    table.Columns.Add(idColumn);
    table.Columns.Add(itemColumn);
    originalDataSet.Tables.Add(table);
    // Add ten rows.

    DataRow newRow;
    for(int i = 0; i < 10; i++)
    {
        newRow = table.NewRow();
        newRow["item"]= "item " + i;
        table.Rows.Add(newRow);
    }
    originalDataSet.AcceptChanges();

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(originalDataSet, "Original DataSet");

    // Write the schema and data to XML file with FileStream.
    string xmlFilename = "XmlDocument.xml";
    System.IO.FileStream streamWrite = new System.IO.FileStream
        (xmlFilename, System.IO.FileMode.Create);

    // Use WriteXml to write the XML document.
    originalDataSet.WriteXml(streamWrite);

    // Close the FileStream.
    streamWrite.Close();

    // Dispose of the original DataSet.
    originalDataSet.Dispose();
    // Create a new DataSet.
    DataSet newDataSet = new DataSet("New DataSet");

    // Read the XML document back in.
    // Create new FileStream to read schema with.
    System.IO.FileStream streamRead = new System.IO.FileStream
        (xmlFilename,System.IO.FileMode.Open);
    newDataSet.ReadXml(streamRead);

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(newDataSet,"New DataSet");
}

private void PrintValues(DataSet dataSet, string label)
{
    Console.WriteLine("\n" + label);
    foreach(DataTable table in dataSet.Tables)
    {
        Console.WriteLine("TableName: " + table.TableName);
        foreach(DataRow row in table.Rows)
        {
            foreach(DataColumn column in table.Columns)
            {
                Console.Write("\table " + row[column] );
            }
            Console.WriteLine();
        }
    }
}

Private Sub DemonstrateReadWriteXMLDocumentWithFileStream()
    ' Create a DataSet with one table and two columns.
    Dim originalDataSet As New DataSet("dataSet")
    Dim table As New DataTable("table")
    Dim idColumn As New DataColumn("id", _
       Type.GetType("System.Int32"))
    idColumn.AutoIncrement = True

    Dim itemColumn As New DataColumn("item")
    table.Columns.Add(idColumn)
    table.Columns.Add(itemColumn)
    originalDataSet.Tables.Add(table)

    ' Add ten rows.
    Dim newRow As DataRow
    Dim i As Integer
    For i = 0 To 9
        newRow = table.NewRow()
        newRow("item") = "item " & i.ToString()
        table.Rows.Add(newRow)
    Next i
    originalDataSet.AcceptChanges()

    ' Print out values of each table in the DataSet 
    ' using the function defined below.
    PrintValues(originalDataSet, "Original DataSet")

    ' Write the schema and data to XML file with FileStream.
    Dim xmlFilename As String = "XmlDocument.xml"
    Dim streamWrite As New System.IO.FileStream _
       (xmlFilename, System.IO.FileMode.Create)

    ' Use WriteXml to write the XML document.
    originalDataSet.WriteXml(streamWrite)

    ' Close the FileStream.
    streamWrite.Close()
     
    ' Dispose of the original DataSet.
    originalDataSet.Dispose()
    ' Create a new DataSet.
    Dim newDataSet As New DataSet("New DataSet")
       
    ' Read the XML document back in. 
    ' Create new FileStream to read schema with.
    Dim streamRead As New System.IO.FileStream _
       (xmlFilename, System.IO.FileMode.Open)
     
    newDataSet.ReadXml(streamRead)
    ' Print out values of each table in the DataSet  
    ' using the function defined below.
    PrintValues(newDataSet, "New DataSet")
End Sub
   
Private Sub PrintValues(dataSet As DataSet, label As String)
    Console.WriteLine(ControlChars.Cr & label)
    Dim table As DataTable
    Dim row As DataRow
    Dim column As DataColumn
    For Each table In  dataSet.Tables
        Console.WriteLine("TableName: " & table.TableName)         
        For Each row In  table.Rows             
            For Each column In  table.Columns
                Console.Write(ControlChars.Tab & " " & _
                   row(column).ToString())
            Next column
            Console.WriteLine()
        Next row
    Next table
End Sub

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果包含的 XML 架构 DataSet ，则 targetNamespace 数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema, as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

另请参阅

• ReadXmlSchema(XmlReader)
• WriteXml(Stream)
• WriteXmlSchema(Stream)
• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET

public:
 System::Data::XmlReadMode ReadXml(System::Xml::XmlReader ^ reader);

public System.Data.XmlReadMode ReadXml (System.Xml.XmlReader reader);

member this.ReadXml : System.Xml.XmlReader -> System.Data.XmlReadMode

Public Function ReadXml (reader As XmlReader) As XmlReadMode

参数

返回

XmlReadMode

用于读取数据的 XmlReadMode。The XmlReadMode used to read the data.

示例

下面的示例首先创建一个简单 DataSet 的，其中包含一个 DataTable 、两个列和10个行。The following example first creates a simple DataSet with one DataTable, two columns, and ten rows. DataSet通过调用方法将架构和数据写入磁盘 WriteXml 。The DataSet schema and data are written to disk by invoking the WriteXml method. 将创建第二个 DataSet ，并 ReadXml 使用方法来填充架构和数据。A second DataSet is created and the ReadXml method is used to fill it with schema and data.

private void DemonstrateReadWriteXMLDocumentWithXMLReader()
{
    // Create a DataSet with one table and two columns.
    DataSet OriginalDataSet = new DataSet("dataSet");
    OriginalDataSet.Namespace= "NetFrameWork";
    DataTable table = new DataTable("table");
    DataColumn idColumn = new DataColumn("id",
        Type.GetType("System.Int32"));
    idColumn.AutoIncrement= true;

    DataColumn itemColumn = new DataColumn("item");
    table.Columns.Add(idColumn);
    table.Columns.Add(itemColumn);
    OriginalDataSet.Tables.Add(table);

    // Add ten rows.
    DataRow newRow;
    for(int i = 0; i < 10; i++)
    {
        newRow = table.NewRow();
        newRow["item"]= "item " + i;
        table.Rows.Add(newRow);
    }
    OriginalDataSet.AcceptChanges();

    // Print out values of each table in the DataSet
    // using the function defined below.
    PrintValues(OriginalDataSet, "Original DataSet");

    // Write the XML schema and data to file with FileStream.
    string xmlFilename = "XmlDocument.xml";

    // Create FileStream
    System.IO.FileStream fsWriteXml =
        new System.IO.FileStream
        (xmlFilename, System.IO.FileMode.Create);

    // Create an XmlTextWriter to write the file.
    System.Xml.XmlTextWriter xmlWriter =
        new System.Xml.XmlTextWriter
        (fsWriteXml, System.Text.Encoding.Unicode);

    // Use WriteXml to write the document.
    OriginalDataSet.WriteXml(xmlWriter, XmlWriteMode.WriteSchema);

    // Close the FileStream.
    fsWriteXml.Close();

    // Dispose of the original DataSet.
    OriginalDataSet.Dispose();

    // Create a new DataSet.
    DataSet newDataSet = new DataSet("New DataSet");

    // Read the XML document back in.
    // Create new FileStream to read schema with.
    System.IO.FileStream fsReadXml =
        new System.IO.FileStream
        (xmlFilename, System.IO.FileMode.Open);

    // Create an XmlTextReader to read the file.
    System.Xml.XmlTextReader xmlReader =
        new System.Xml.XmlTextReader(fsReadXml);

    // Read the XML document into the DataSet.
    newDataSet.ReadXml(xmlReader, XmlReadMode.ReadSchema);

    // Close the XmlTextReader
    xmlReader.Close();

    // Print out values of each table in the DataSet
    // fusing the unction defined below.
    PrintValues(newDataSet,"New DataSet");
}

private void PrintValues(DataSet dataSet, string label)
{
    Console.WriteLine("\n" + label);
    foreach(DataTable table in dataSet.Tables)
    {
        Console.WriteLine("TableName: " + table.TableName);
        foreach(DataRow row in table.Rows)
        {
            foreach(DataColumn column in table.Columns)
            {
                Console.Write("\t{0}({1})='{2}'", column.ColumnName, column.DataType.Name, row[column]);
            }
            Console.WriteLine();
        }
    }
}

Private Sub DemonstrateReadWriteXMLDocumentWithXMLReader()
    ' Create a DataSet with one table and two columns.
    Dim OriginalDataSet As New DataSet("dataSet")
    OriginalDataSet.Namespace = "NetFrameWork"
    Dim table As New DataTable("table")
    Dim idColumn As New DataColumn("id", _
        Type.GetType("System.Int32"))
    idColumn.AutoIncrement = True

    Dim itemColumn As New DataColumn("item")
    table.Columns.Add(idColumn)
    table.Columns.Add(itemColumn)
    OriginalDataSet.Tables.Add(table)

    ' Add ten rows.
    Dim newRow As DataRow
    Dim i As Integer
    For i = 0 To 9
        newRow = table.NewRow()
        newRow("item") = "item " & i.ToString()
        table.Rows.Add(newRow)
    Next i
    OriginalDataSet.AcceptChanges()

    ' Print out values of each table in the DataSet 
    ' using the function defined below.
    PrintValues(OriginalDataSet, "Original DataSet")

    ' Write the XML schema and data to file with FileStream.
    Dim xmlFilename As String = "XmlDocument.xml"

    ' Create FileStream    
    Dim fsWriteXml As New System.IO.FileStream _
        (xmlFilename, System.IO.FileMode.Create)

    ' Create an XmlTextWriter to write the file.
    Dim xmlWriter As New System.Xml.XmlTextWriter _
        (fsWriteXml, System.Text.Encoding.Unicode)

    ' Use WriteXml to write the document.
    OriginalDataSet.WriteXml(xmlWriter, XmlWriteMode.WriteSchema)

    ' Close the FileStream.
    fsWriteXml.Close()
        
    ' Dispose of the original DataSet.
    OriginalDataSet.Dispose()

    ' Create a new DataSet.
    Dim newDataSet As New DataSet("New DataSet")
        
    ' Read the XML document back in. 
    ' Create new FileStream to read schema with.
    Dim fsReadXml As New System.IO.FileStream _
        (xmlFilename, System.IO.FileMode.Open)

    ' Create an XmlTextReader to read the file.
    Dim xmlReader As New System.Xml.XmlTextReader(fsReadXml)

    ' Read the XML document into the DataSet.
    newDataSet.ReadXml(xmlReader, XmlReadMode.ReadSchema)

    ' Close the XmlTextReader
    xmlReader.Close()
        
    ' Print out values of each table in the DataSet using the 
    ' function defined below.
    PrintValues(newDataSet, "New DataSet")
End Sub
    
    
 Private Sub PrintValues(dataSet As DataSet, label As String)
     Console.WriteLine(ControlChars.Cr & label)
     Dim table As DataTable
     Dim row As DataRow
     Dim column As DataColumn
     For Each table In  dataSet.Tables
         Console.WriteLine("TableName: " & table.TableName)
         For Each row In  table.Rows
             For Each column In  table.Columns
                 Console.Write(ControlChars.Tab & "{0}({1})='{2}'", column.ColumnName, column.DataType.Name, row(column).ToString())

             Next column
             Console.WriteLine()
         Next row
     Next table
  End Sub

注解

ReadXml方法提供了一种方法，用于从 XML 文档只读取数据或将数据和架构读入到 DataSet 中，而 ReadXmlSchema 方法只读取架构。The ReadXml method provides a way to read either data only, or both data and schema into a DataSet from an XML document, whereas the ReadXmlSchema method reads only the schema. 若要读取数据和架构，请使用 ReadXML 包含参数的重载之一 mode ，并将其值设置为 ReadSchema 。To read both data and schema, use one of the ReadXML overloads that includes the mode parameter, and set its value to ReadSchema.

请注意，对于和方法也是 WriteXml 如此 WriteXmlSchema 。Note that the same is true for the WriteXml and WriteXmlSchema methods, respectively. 若要从编写 XML 数据或同时编写架构和数据 DataSet ，请使用 WriteXml 方法。To write XML data, or both schema and data from the DataSet, use the WriteXml method. 若要只写入架构，请使用 WriteXmlSchema 方法。To write just the schema, use the WriteXmlSchema method.

如果指定了内嵌架构，则在加载数据之前，使用内联架构来扩展现有的关系结构。If an in-line schema is specified, the in-line schema is used to extend the existing relational structure prior to loading the data. 例如，如果存在任何冲突 (例如，使用不同数据类型定义的同一表中的同一列) 会引发异常。If there are any conflicts (for example, the same column in the same table defined with different data types) an exception is raised.

如果未指定内联架构，根据 XML 文档的结构，将根据需要通过推理扩展关系结构。If no in-line schema is specified, the relational structure is extended through inference, as necessary, according to the structure of the XML document. 如果无法通过推理扩展架构以便公开所有数据，则会引发异常。If the schema cannot be extended through inference in order to expose all data, an exception is raised.

如果的 XML 架构 DataSet 包含 targetNamespace ，则数据可能不会被读取，并且在调用 ReadXml 以加载 DataSet 包含元素且无限定命名空间的 xml 时可能会遇到异常。If the XML Schema for a DataSet includes a targetNamespace, data may not be read, and you may encounter exceptions when calling ReadXml to load the DataSet with XML that contains elements with no qualifying namespace. 若要读取未限定的元素，请 elementFormDefault 在 XML 架构中设置等于 "合格的"，如下面的示例所示。To read unqualified elements, set elementFormDefault equal to "qualified" in your XML Schema as the following example demonstrates.

<xsd:schema id="MyDataSet"   
   elementFormDefault="qualified"   
   targetNamespace="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns="http://www.tempuri.org/MyDataSet.xsd"   
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"   
   xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">  
</xsd:schema>  

System.Xml.XmlTextReader 从 XmlReader 继承。System.Xml.XmlTextReader inherits from XmlReader.

另请参阅

• 在 ADO.NET 中使用数据集Using DataSets in ADO.NET