我有一个C#winform应用程序,将文件保存到sqlserver数据库(2014)到VAR二进制(MAX)字段
功能保存
byte[] Bytefile;
using (SqlConnection conn = new SqlConnection(DataHelper.GetConnection()))
{
conn.Open();
DataTable dt = new DataTable();
SqlCommand comm = new SqlCommand("Delete T_Articale_Files where Artricle_id=" + ID, conn);
comm.ExecuteNonQuery();
foreach (string file in Directory.GetFiles(varFilePath))
{
using (var stream = new FileStream(Path.Combine(varFilePath, file), FileMode.Open, FileAccess.Read))
{
using (var reader = new BinaryReader(stream))
{
Bytefile = reader.ReadBytes((int)stream.Length);
}
}
using (var sqlWrite = new SqlCommand("INSERT INTO T_Articale_Files (Artricle_id,FileName,FileData) Values(@ID,@FileName,@File)", conn))
{
sqlWrite.Parameters.Add("@ID", SqlDbType.Int, 10).Value = ID;
sqlWrite.Parameters.Add("@FileName", SqlDbType.NVarChar, 50).Value = Path.GetFileName(file);
sqlWrite.Parameters.Add("@File", SqlDbType.VarBinary, file.Length).Value = Bytefile;
sqlWrite.ExecuteNonQuery();
}
}
}
要检索的函数
using (SqlConnection conn = new SqlConnection(DataHelper.GetConnection()))
// using (var varConnection = Locale.sqlConnectOneTime(Locale.sqlDataConnectionDetails))
{
conn.Open();
DataTable dt = new DataTable();
SqlCommand comm = new SqlCommand("SELECT id,FileName FROM T_Articale_Files WHERE Artricle_id = @varID", conn);
comm.Parameters.AddWithValue("@varID", varID);
dt.Load(comm.ExecuteReader());
foreach (DataRow item in dt.Rows)
{
using (var sqlQuery = new SqlCommand(@"SELECT FileData FROM T_Articale_Files WHERE id = @ID", conn))
{
sqlQuery.Parameters.AddWithValue("@ID", item["id"]);
using (var sqlQueryResult = sqlQuery.ExecuteReader())
while (sqlQueryResult.Read())
{
var blob = new Byte[(sqlQueryResult.GetBytes(0, 0, null, 0, int.MaxValue))];
sqlQueryResult.GetBytes(0, 0, blob, 0, blob.Length);
using (var fs = new FileStream(Path.Combine(varPathToNewLocation, item["FileName"].ToString()), FileMode.Create, FileAccess.Write))
fs.Write(blob, 0, blob.Length);
}
}
}
}
这工作很好,现在我已经要求将数据库转换为XML,用于未连接到服务器的PC
转换为XML的函数
var xmlFileData = "";
DataSet ds = new DataSet();
var tables = new[] { "V_Articale", "T_Articale", "T_City", "T_Classification", "T_Country", "T_Locations", "T_milishia", "T_Search", "T_statistics", "T_TerrorGroups", "T_Tribes", "T_Users", "T_Articale_Files" };
foreach (var table in tables)
{
var query = "SELECT * FROM " + table;
SqlConnection conn = GetConnection();
SqlCommand cmd = new SqlCommand(query, conn);
conn.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt = new DataTable(table);
da.Fill(dt);
conn.Close();
conn.Dispose();
ds.Tables.Add(dt);
if(table== "T_Articale_Files")
{
foreach (DataRow item in dt.Rows)
{
Byte[] file = GetBytes(item["FileData"].ToString());
}
}
}
xmlFileData = ds.GetXml();
它工作正常,除了二进制文件,当
输出XML
<T_Articale_Files>
<id>6</id>
<Artricle_id>1013</Artricle_id>
<FileName>falcon banner.jpg</FileName>
<FileData>/9j/4AAQSkZJRgABAgEASABIAAD/4QleRXhpZgAATU0AKgAAAAgABwESAAMAAAABAAEAAAEaAAUAAAABAAAAYgEbAAUA</FileData>
当尝试将其转换回图像时,它会给我1kb的文件,字符串不是实际图像
二进制字段有特殊的转换吗?
非常感谢。
编辑问题解决感谢@grek40解决方案转换为XML
var xmlstream = new StringWriter();
ds.WriteXml(xmlstream, XmlWriteMode.WriteSchema);
string xmlWithSchema = xmlstream.ToString();
其中ds是一个数据集
转换回文件
private void databaseFileRead(int varID, string varPathToNewLocation)
{
DataSet ds = new DataSet();
ds.ReadXml(XMLpath);
DataTable dt = new DataTable();
dt = ds.Tables["T_Articale_Files"];
DataView dv = new DataView(dt);
dv.RowFilter = "Artricle_id=" + varID;
if (dv.Count > 0)
{
foreach (DataRowView item in dv)
{
byte[] stringArray = (byte[])(item["FileData"]);
File.WriteAllBytes(Path.Combine(Filepath, item["FileName"].ToString()), stringArray ); // save image to disk
}
}
为了对二进制数据进行可逆字符串编码,可以使用Base64编码
public byte[] StrToByteArray(string str)
{
return Convert.FromBase64String(str);
}
public string ByteArrToString(byte[] byteArr)
{
return Convert.ToBase64String(byteArr);
}
将字节转换为存储在xml中的字符串,并在使用时从字符串还原字节。
最初,数据被正确地写入xml。问题很可能出在检索函数上。由于xml不包含模式信息,它将处理
为了允许正确的重读,您需要在读取时使用预定义的模式,或者使用表编写模式:
dataSet.WriteXml(filenameOrStream, XmlWriteMode.WriteSchema)
// later read the xml and it will respect the schema information
dataSet.ReadXml(filenameOrStream);
不同方面的小样本:
var sourceDataSet = new DataSet();
var sourceTable = new DataTable("TableWithBinary");
sourceDataSet.Tables.Add(sourceTable);
sourceTable.Columns.Add("Id");
sourceTable.Columns.Add("File", typeof(byte[]));
sourceTable.Rows.Add(1, new byte[] { 1, 0, 2 });
sourceTable.Rows.Add(2, new byte[] { 1, 3, 2 });
// write option 1
string schema = sourceDataSet.GetXmlSchema();
string getxml = sourceDataSet.GetXml();
// write option 2
var writexmlstream = new StringWriter();
sourceDataSet.WriteXml(writexmlstream, XmlWriteMode.WriteSchema);
string writexmlWithSchema = writexmlstream.ToString();
// read wrong (missing schema)
var targetCorrupted = new DataSet();
targetCorrupted.ReadXml(new StringReader(getxml));
// read correct with schema in every xml file
var targetFromXmlWithSchema = new DataSet();
targetFromXmlWithSchema.ReadXml(new StringReader(writexmlWithSchema));
// read correct with separate schema definition and data
var targetFromXml = new DataSet();
targetFromXml.ReadXmlSchema(new StringReader(schema));
targetFromXml.ReadXml(new StringReader(getxml));
XML中二进制文件的标准格式是base64
。我不认为,上面有什么问题。。。
您必须记住,XML中禁止使用几个字符。您不能仅仅在两个XML标记之间填充二进制数据。如果有一个的数字代码
显示的字符串看起来很像base64代码。
试试这个
DECLARE @string VARCHAR(100)='Hello World with forbidden characters (< & >)';
DECLARE @binary VARBINARY(MAX) = CAST(@string AS VARBINARY(MAX));
DECLARE @xml XML=(SELECT @string AS string, @binary AS bin FOR XML PATH('test'));
SELECT @xml;
--结果(编码实体和二进制隐式转换为base64)
<test>
<string>Hello World with forbidden characters (< & >)</string>
<bin>SGVsbG8gV29ybGQgd2l0aCBmb3JiaWRkZW4gY2hhcmFjdGVycyAoPCAmID4p</bin>
</test>
--现在我们从XML中读取(实体被重新编码,二进制表示为十六进制字符串,可以将其重新转换为前者VARCHAR(MAX)
SELECT @xml.value('(/test/string)[1]','nvarchar(max)') AS TheStringAsIs
,@xml.value('(/test/bin)[1]','varbinary(max)') AS TheStringAsBinary_HEX
,CAST(@xml.value('(/test/bin)[1]','varbinary(max)') AS VARCHAR(100)) AS ReConverted
结果
The string *as-is*: Hello World with forbidden characters (< & >)
binary data HEX: 0x48656C6C6F20576F726C64207769746820666F7262696464656E206368617261637465727320283C2026203E29
ReConverted: Hello World with forbidden characters (< & >)