[Android instance] File Download and storage of downloaded files to the SD card

Public  String downloadtext (string urlstr) {stringbuffer sb = New  Stringbuffer (); string line = Null  ; Bufferedreader Buffer = Null  ;  Try  {  //  Create a URL object Url = New  URL (urlstr );  // Create an HTTP Connection  Try  {Httpurlconnection urlconn = (Httpurlconnection) URL. openconnection ();  //  Read data using Io streams Buffer = New Bufferedreader ( New  Inputstreamreader (urlconn. getinputstream ()));  While (Line = buffer. Readline ())! = Null  ) {Sb. append (line );}}  Catch (Ioexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}}  Catch  (Malformedurlexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}  Return  SB. tostring ();} 

 /*  * This function returns an integer-1, indicating an error occurred while downloading the object. * 0: indicates that the downloaded file is successful. * 1: indicates that the downloaded file already exists.  */ Public   Int  Downloadfile (string urlstr, string path, string filename) {inputstream = Null  ; Gotosdcard = New  Gotosdcard ();  If (Gotosdcard. isfileexist (path + Filename )){  Return 1 ;}  Else  {  Try {URL = New  URL (urlstr); httpurlconnection urlconn = (Httpurlconnection) URL. openconnection (); inputstream = Urlconn. getinputstream (); file resultfile = Gotosdcard. write2sdfrominput (path, filename, inputstream ); //  Save the data stream to the SD card  If (Resultfile = Null  ){  Return -1 ;}} Catch  (Malformedurlexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}  Catch  (Ioexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}  Finally  {  Try  {Inputstream. Close ();}  Catch (Ioexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}}}  Return 0 ;} 

 Public   Class  Gotosdcard {  Private String sdpath = Null  ;  Public  String getsdpath (){  Return Sdpath ;}  Public  Gotosdcard (){  //  Obtain the directory of the current external storage device.  //  Sdcard Sdpath = environment. getexternalstoragedirectory () + "" ; System. Out. println ( "Sdpath =" + Sdpath );}  /*  * Create a file on the SD card  */  Public  File creatsdfile (string filenmae) {file File =New File (sdpath + Filenmae );  Try  {File. createnewfile ();}  Catch  (Ioexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}  Return  File ;}  /*  * Create a directory on the SD card  */  Public File creatsddir (string dirname) {file dir = New File (sdpath + Dirname );  If (! Dir. exists () {dir. mkdirs ();}  Return  Dir ;}  /*  * Determine whether the folder on the SD card exists  */  Public   Boolean  Isfileexist (string filename) {file File = New File (sdpath +Filename );  Return  File. exists ();}  /*  * Write data from an inputsteam instance to the SD card.  */  Public  File write2sdfrominput (string path, string filename, inputstream input) {system. Out. println ( "Path =" + path + "; filename =" + filename + ";" ); File File = Null  ; File folder = Null  ; Outputstream output =Null  ;  Try  {Folder = Creatsddir (PATH); system. Out. println ( "Folder =" + Folder); File = Creatsdfile (path + Filename); system. Out. println ( "File =" + File); Output = New  Fileoutputstream (File );  Byte Buffer [] = New   Byte [4*1024];  While (Input. Read ())! =-1 ) {Output. Write (buffer);} output. Flush ();}  Catch  (Ioexception e ){  //  Todo auto-generated Catch Block  E. printstacktrace ();}  Finally  {  Try  {Output. Close ();}  Catch  (Exception e) {e. printstacktrace ();}}  Return File ;}} 

 
<Uses-PermissionAndroid: Name= "Android. Permission. Internet"/>// Permissions required for downloading files from the network<Uses-PermissionAndroid: Name= "Android. Permission. write_external_storage"/>// Write permission to the SD card