Image File Operations

I. Operation points:

• Convert the file to binary, and then convert the binary to a file.
• Write the file to XML, read it, and display or restore it.
• Write the file to the database and read it for display or restoration.

Ii. learning knowledge points:

Binary operations: filestream, binaryreader, and binarywriter)

 

3. Procedure:

(1) create a class:Filetodata. CS

Using system; <br/> using system. collections. generic; <br/> using system. LINQ; <br/> using system. web; <br/> using system. io; </P> <p> // <summary> <br/> // Summary of filetodata <br/> /// </Summary> <br/> Public class filetodata <br/>{< br/> Public filetodata () <br/> {<br/> // todo: add the constructor logic here <br/> // <br/>}</P> <p> Public static string filetobinary (string filepath) <br/>{< br/> filestream FS = new filestream (filepath, filemode. open, fileaccess. read); <br/> binaryreader BR = new binaryreader (FS); <br/> int length = (INT) FS. length; <br/> byte [] B = new byte [length]; <br/> for (INT I = 0; I <length; I ++) <br/> {<br/> B [I] = BR. readbyte (); <br/>}< br/> console. writeline ("interval ay: {0}", B); <br/> string strdata = convert. tobase64string (B); // 8-bit unsigned integer array tobase64 <br/> Br. close (); <br/> FS. close (); <br/> // convert the array to a string character <br/> return strdata; </P> <p >}</P> <p> Public static void binarytofile (string path, string binary) <br/>{< br/> filestream FS = new filestream (path, filemode. create, fileaccess. write); <br/> binarywriter BW = new binarywriter (FS); <br/> BW. write (convert. frombase64string (Binary); <br/> BW. close (); // close the binary stream writer <br/> FS. close (); // close the file stream </P> <p >}</P> <p>}

(2) tobinary. aspx ):

Protected void page_load (Object sender, eventargs e) <br/>{< br/> string a = filetodata. filetobinary (server. mappath ("~ /Image 1.jpg "); // convert image 1 to binary <br/> filetodata. binarytofile (server. mappath ("~ /Image 2.jpg "), a); // convert binary to Image 2 </P> <p>}

(3) create a class:Filetoxml. CS

Add namespace: using system. IO; using system. Text; using system. xml;

/// <Summary> <br/> // convert the file to binary <br/> /// </Summary> <br/> public class filetoxml <br/> {<br/> Public filetoxml () <br/>{< br/>}< br/> /// <summary> <br/> // from the upload Control <br/> /// </ summary> <br/> // <Param name = "Fu"> fileupload upload control of the file to be loaded </param> <br/> // <Param name = "xmlpath"> storage location of XML files </param> <br/> // <Param name = "ID"> image id </param> <br/> public static void filetoxml (fileupload Fu, string xmlpath, Guid ID) <br/>{< br/> If (Fu. hasfile) <br/> {// first judge whether the fileupload object contains the file <br/> string pathstring = Fu. filename; <br/> int filelength = Fu. postedfile. contentlength; // only get the file name with the extension </P> <p> try <br/> {<br/> byte [] filebytearray = new byte [filelenght]; <br/> // declare a byte array with the total size of the file to store the binary data to be generated. </P> <p> stream streamobj = Fu. postedfile. inputstream; <br/> // create a stream object that can read the content of the uploaded file </P> <p> streamobj. read (F Ilebytearray, 0, filelength); <br/> // use the stream object reading method. The parameter description stores the data stream in the declared array and reads it from 0, the number of bytes read is all </P> <p> xmldocument xdom = new xmldocument (); </P> <p> If (! File. exists (xmlpath) <br/> {// if no XML exists, create </P> <p> xmldeclaration xdec = xdom. createxmldeclaration ("1.0", "UTF-8", null); <br/> xdom. appendchild (xdec); // create the first line declaration </P> <p> xmlelement root = xdom. createelement ("file"); // create the root node file <br/> xdom. appendchild (Root); </P> <p> xmlelement rootelement = xdom. createelement ("image"); // create the parent node image <br/> root. appendchild (rootelement); </P> <p> xmlelement childelementid = xdom. createelement ("guid"); // image Id field <br/> childelementid. innertext = ID. tostring (); <br/> // use the recent guid number as its serial value <br/> rootelement. appendchild (childelementid); </P> <p> xmlelement childelementimgsize = xdom. createelement ("size"); // file size field <br/> childelementimgsize. innertext = filelength. tostring (); <br/> rootelement. appendchild (childelementimgsize); </P> <p> xmlelement childelementimgdata = xdom. createelement ("imgdata"); // Image Information <br/> childelementimgdata. innertext = convert. tobase64string (filebytearray); <br/> // This sentence is critical. Convert the preceding array to a string and save it <br/> rootelement. appendchild (childelementimgdata); </P> <p> xdom. save (xmlpath ); <br/> // Save the framework created above to the specified XML file <br/>}< br/> else <br/>{// if the XML file exists find the corresponding node directly, then add <br/> xdom. load (xmlpath); // load the XML document <br/> // read the specified XML file to the xmldocument object </P> <p> xmlnode root = xdom. selectsinglenode ("file"); <br/> // use an XPATH expression to find the node that matches the condition, here, of course, it refers to the root node </P> <p> xmlelement rootelement = xdom. createelement ("image"); <br/> root. appendchild (rootelement); <br/> // create a parent node </P> <p> xmlelement childelementid = xdom. createelement ("guid"); // image Id field <br/> childelementid. innertext = ID. tostring (); // uses the recent guid number as its serial value <br/> rootelement. appendchild (childelementid); </P> <p> xmlelement childelementimgsize = xdom. createelement ("size"); <br/> childelementimgsize. innertext = filelenght. tostring (); // file size field <br/> rootelement. appendchild (childelementimgsize); </P> <p> xmlelement childelementimgdata = xdom. createelement ("imgdata"); <br/> childelementimgdata. innertext = convert. tobase64string (Fu. filebytes); <br/> rootelement. appendchild (childelementimgdata); </P> <p> xdom. save (xmlpath ); <br/> // Save the framework created above to the specified XML file <br/>}< br/> catch (exception E) <br/>{< br/> throw E; <br/>}< br/>

(4) write the image file to XML and then read it for display or restoration (filetoxml. aspx ):

Public partial class filetoxml: system. web. UI. page <br/>{< br/> protected void button#click (Object sender, eventargs e) <br/>{// (upload button) write the file into XML <br/> string xmlpath = server. mappath ("~ /App_data/imgxml. XML "); <br/> guid gid = guid. newguid (); <br/> filetoxml. filetoxml (fileupload1, xmlpath, GID); </P> <p> session ["gid"] = GID; <br/>}< br/> protected void button2_click (Object sender, eventargs E) <br/> {// obtain an image based on the GID. <br/> readimgfromxml (guid) session ["gid"]); <br/>}< br/> private void readimgfromxml (guid GID) <br/>{< br/> xmldocument xdom = new xmldocument (); <br/> xdom. load (Ser Ver. mappath ("~ /App_data/imgxml. XML "); </P> <p> xmlnodelist xnl = xdom. selectsinglenode ("// image [guid = '" + GID. tostring () + "']"). childnodes; // find all the subnodes of the node whose guid = the ID we passed in <br/> for (INT I = 0; I <xnl. count; I ++) <br/>{< br/> string imgdata = xnl. item (2 ). innertext; // The third item of the node imgdata <br/> response. outputstream. write (convert. frombase64string (imgdata), 0, imgdata. length); <br/> response. end (); // print all imgd from 0 to the specified length ATA Image Information <br/>}< br/> protected void button3_click (Object sender, eventargs E) <br/> {// read from XML and convert it to a file <br/> xmldocument xdom = new xmldocument (); <br/> xdom. load (server. mappath ("~ /App_data/imgxml. XML "); </P> <p> xmlnodelist xnl = xdom. selectsinglenode ("// image [guid = '" + session ["gid"]. tostring () + "']"). childnodes; <br/> for (INT I = 0; I <xnl. count; I ++) <br/>{< br/> string strdata = xnl. item (2 ). innertext; <br/> filestream FS = new filestream (server. mappath ("~ /Image file name .gif "), filemode. create, fileaccess. write); <br/> binarywriter BW = new binarywriter (FS); <br/> BW. write (convert. frombase64string (strdata); <br/> BW. close (); <br/> FS. close (); <br/>}< br/> image1.imageurl = "~ /Image file name .gif "; <br/>}< br/>

(5) write the image file to the database and then read it for display or restoration (todata. aspx)

Public partial class todata: system. web. UI. page <br/>{< br/> protected void button#click (Object sender, eventargs e) <br/>{</P> <p> guid gid = guid. newguid (); <br/> sqlconnection conn = new sqlconnection (configurationmanager. connectionstrings ["Data Source Name"]. connectionstring); <br/> Conn. open (); <br/> // note: binary data cannot be written to the database by adding strings. </P> <p> sqlcommand cmd = new sqlcommand ("insert into IMG (GID, filedata) values (@ GID, @ filearray) ", Conn); // create a table named IMG and add the field name GID and filedata. Add the field type below <br/> cmd. parameters. add ("@ gid", sqldbtype. uniqueidentifier ). value = GID; <br/> cmd. parameters. add ("@ filearray", sqldbtype. image ). value = fileupload1.filebytes; <br/> cmd. executenonquery (); // execute the SQL statement and return the number of affected rows. <br/> Conn. close (); </P> <p> session ["gid"] = GID; // Save the value of GID <br/>}< br/> protected void button2_click (Object sender, eventargs E) <br/>{< br/> sqlconnection conn = new sqlconnection (configurationmanager. connectionstrings ["Data Source Name"]. connectionstring); <br/> Conn. open (); <br/> sqlcommand cmd = new sqlcommand ("select filedat from IMG where gid = '" + session ["gid"]. tostring () + "'", Conn); <br/> byte [] FBT = (byte []) cmd. executescalar (); <br/> Conn. close (); </P> <p> response. outputstream. write (FBT, 0, FBT. length); <br/> response. end (); </P> <p >}< br/>}