Common tool methods for file operations

Writing section to file:

/*** Tool method, write bytes to file Delete file if the writing process is abnormal * *@parambytes *@paramfile*/     Public Static voidWritebytestofile (byte[] bytes, file file) {Randomaccessfile Access=NULL; Try{Access=NewRandomaccessfile (file, "RW");        Access.write (bytes); } Catch(IOException e) {if(E.getmessage ()! =NULL) {LOG.E ("JsonUtil2", E.getmessage ());        } file.delete (); } finally{jsonutil.release (access); }    }

bytes of random Read files:

/*** Tool method, random location read bytes of file * *@paramfile *@paramposition *@paramlength *@return     */     Public Static byte[] readFile (File file,intPositionintlength) {        if(File = =NULL|| !file.exists () | | !File.isfile ()) {            return NULL; } randomaccessfile Access=NULL; byte[] bytes =New byte[length]; Try{Access=NewRandomaccessfile (file, "R");            Access.seek (position); Access.readfully (Bytes,0, length); returnbytes; } Catch(Exception e) {if(E.getmessage ()! =NULL) {LOG.E ("JsonUtil2", E.getmessage ()); }            return NULL; } finally{jsonutil.release (access); }    }

Read all bytes of the file:

/*** Tool method, read bytes of file * *@paramfile *@return     */    Private Static byte[] readFile (file file) {if(File = =NULL|| !file.isfile () | | !File.canread ()) {            return NULL; } FileInputStream FIS=NULL; Bufferedinputstream bis=NULL; LongFileSize =file.length (); if(FileSize >integer.max_value) {System.out.println ("File Too big ..."); return NULL; } bytearrayoutputstream Bos=NewBytearrayoutputstream ((int) fileSize); Try{bis=NewBufferedinputstream (Newfileinputstream (file)); intBuf_size = 1024; byte[] buffer =New byte[Buf_size]; intLen = 0;  while( -1! = (len = bis.read (buffer, 0, buf_size))) {bos.write (buffer,0, Len); }            returnBos.tobytearray (); } Catch(IOException e) {LOG.E ("JsonUtil2", "Read bytes form file error"); return NULL; } finally{jsonutil.release (FIS);        Jsonutil.release (bis); }    }

read out the string from the file:

/*** Read the string from the given file * *@paramfile *@returnstring, NULL if the file does not exist*/     Public StaticString readfromfile (file file) {if(File = =NULL|| !file.exists () | | !File.isfile ()) {LOG.E ("Jsonutil", "Cannot read file"); return NULL; } StringBuilder Sbuilder=NewStringBuilder (""); FileReader FR=NULL; BufferedReader BR=NULL; Char[] buffer =New Char[1024]; intLength =-1; Try{FR=Newfilereader (file); BR=NewBufferedReader (FR);  while(length = br.read (buffer))! =-1) {sbuilder.append (buffer,0, length); }        } Catch(FileNotFoundException e) {e.printstacktrace (); } Catch(IOException e) {e.printstacktrace (); } finally{Release (FR);        Release (BR); }        if(sbuilder.length () = = 0) {//if the length after reading is still zero            return NULL; }        //log.i ("bbbbb", "" +sbuilder.tostring ());//Test        /*** To determine if the first char is not a UTF8 BOM file header If yes, remove the first char*/        if(Getthechar (). Equals (((Character) (Sbuilder.charat (0))) {Sbuilder.deletecharat (0); }        returnsbuilder.tostring (); }

Release closable Resources:

 /**   * release closable resources * *   @param   closeobj  */
     public  static  void   release (closeable closeobj) {  If  (closeobj! = null  ) { try   {closeobj.close ();  catch   (IOException e) {e.printst            Acktrace ();        } closeobj  = null  ; }    }

Write String to file:

/*** Writes the specified string to the specified file, overwriting write * *@paramfile *@paramSTR *@param Cover * Overwrite write, true overwrite, false append*/    Private Static voidwritetofile (file file, String str, Boolean cover) {cover= !cover; if(File = =NULL|| !file.exists () | | !File.isfile ()) {LOG.E ("Jsonutil", "Cannot write file"); return; }        if(str = =NULL) {            return; } FileWriter FW=NULL; BufferedWriter BW=NULL; Try{FW=NewFileWriter (file, cover); Bw=NewBufferedWriter (FW); //log.e ("Jsonutil", File.getabsolutepath ());bw.write (str);        Bw.flush (); } Catch(FileNotFoundException e) {e.printstacktrace (); } Catch(IOException e) {e.printstacktrace (); } finally{release (FW);        Release (BW); }    }

Utf-8 file header with BOM:

/*** Get UTF8 file header char * *@return     */    Private StaticCharacter Getthechar () {byteA = (byte) 239;//0xEF (byte) 0xef;eb        byteB = (byte) 187;//(byte) 0XBB;BC        bytec = (byte) 191;//0xbf;80//char ret =//( Char) (((A&0X000000FF) <<24) | ( B&0X000000FF) <<16|        (C&0X000000FF) <<8|0x00000000); //return (Character) ret;        Char[] chars = GetChars (New byte[] {A, B, C}); return(Character) Chars[0]; }    /*** bytes Turn chars * *@parambytes *@return     */    Private Static Char[] GetChars (byte[] bytes) {Charset cs= Charset.forname ("UTF-8"); Bytebuffer BB=bytebuffer.allocate (bytes.length);        Bb.put (bytes);        Bb.flip (); Charbuffer CB=Cs.decode (BB); returnCb.array (); }

Common tool methods for file operations