Reading and Writing SD card files in Android

1. Use the mksdcard command to create a 128 m sd card image named sdcard. IMG (m must be capitalized.
Mksdcard 128 M sdcard. img
2. Copy sdcard. IMG to D: \ projects2 and set the startup parameters in the run configuration dialog box in eclipse.
-Sdcard D: \ projects2 \ sdcard. img

In this way, the SD card is available.
3. add content to sdcard
ADB push E: \ Xunlei \ give.mp3/sdcard/give.mp3.
4. Read and Write files in the Application

Note: If you want to write the SD card in the application,

Android. Permission. write_external_storage must be added with the androi permission.

As follows:
<Uses-Permission Android: Name = "android. Permission. write_external_storage"> </uses-Permission>
Instance 1:
Button button6 = (button) findviewbyid (R. Id. button06 );

Onclicklistener listener6 = new onclicklistener (){

@ Override
Public void onclick (view v ){
Createsdfile ();
}
};
Button6.setonclicklistener (listener6 );
Button button7 = (button) findviewbyid (R. Id. button07 );
Onclicklistener listener7 = new onclicklistener (){
@ Override
Public void onclick (view v ){
Writesdfile (kfilename );
}
};
Button7.setonclicklistener (listener7 );

Button button8 = (button) findviewbyid (R. Id. button08 );
Onclicklistener listener8 = new onclicklistener (){
@ Override
Public void onclick (view v ){
Readsdfile (kfilename );
}
};
Button8.setonclicklistener (listener8 );



String kfilename = "/sdcard/uad2/test.txt ";

Void createsdfile ()

{

Createsdfile (kfilename );

}

Final Static string ksdcardroot = "sdcard ";

Void createsdfile (string filefullname)

{

If (filefullname. charat (0) = '/')
Filefullname = filefullname. substring (1, filefullname. Length ());
String name [] = filefullname. Split ("/");
If (name = NULL | Name. Length <2)

Return;

If (! Name [0]. Equals (ksdcardroot ))

{

Log. I (TAG, filefullname + "is not a file" + name [0]);

Return;

}

File sddir = new file ("/" + ksdcardroot );

If (! Sddir. exists ())

{

Log. I (TAG, "SD card is not exists ");

Return;

}

If (! Sddir. canwrite ())

{

Log. I (TAG, sddir. Length () + "SD card can not be wrote" + sddir. Canread ());

Return;

}

File dir = sddir;

For (INT I = 1; I <name. Length-1; I ++)

{

Dir = new file (dir. getabsolutepath () + "/" + name [I]);

If (dir. exists ())

Continue;

Boolean res = dir. mkdir ();

If (! Res)

{

Log. I (TAG, "Create dir:" + Res + "fail" + name [I]);

Return;

}

}

String filename = Name [name. Length-1]. Trim ();

If (filename. Length ()> 0)

{

File file = new file (dir. getabsolutepath () + "/" + name [name. Length-1]);

If (! File. exists ())

{

Try {

File. createnewfile ();

} Catch (ioexception E)

{

Log. E (TAG, "creat file erro:", e );

}

}

}

}

Void writesdfile (string filename)

{
File file = new file (filename );

If (! File. exists ())

Createsdfile (filename );

If (! File. canwrite ())

{

Log. I (TAG, "file:" + file. getabsolutefile () + "can not to be wrote ");

Return;

}

String content = "Hello:" + system. currenttimemillis ();

Fileoutputstream OS = NULL;

Try {

OS = new fileoutputstream (File );

OS. Write (content. getbytes ());

Log. I (TAG, "write:" + content );

}

Catch (ioexception E)

{

Log. E (TAG, "Write File", e );

}

Finally
{
If (OS! = NULL)
{
Try {
OS. Flush ();
OS. Close ();
} Catch (ioexception E)
{
Log. E (TAG, "Close file", e );
}
}
}

}

Void readsdfile (string filename)

{
String content;

Fileinputstream is = NULL;

File file = new file (filename );

If (! File. exists ())

{

Log. I (TAG, file. getabsolutepath () + "is not exists ");

Return;
}
If (! File. Canread ())

{

Log. I (TAG, file. getabsolutepath () + "can not be read ");

Return;
}
Try {

Is = new fileinputstream (File );

Byte buffer [] = new byte [is. Available ()];

Is. Read (buffer );

Content = new string (buffer );

Log. I (TAG, "Read SD file:" + content );

// Inputstreamreader inreader = new inputstreamreader (is );
}
Catch (ioexception E)

{

Log. E (TAG, "Write File", e );

}

Finally
{
If (is! = NULL)
{
Try {
Is. Close ();
} Catch (ioexception E)
{
Log. E (TAG, "Close file", e );
}
}
}

}