Byte to InputStream or OutputStream

Question

I have a blob column in my database table  for which I have to use byte   in my Java program as a mapping and to use this data I have to convert it to InputStream or OutputStream  But I don t know what happens internally when I do so  Can anyone briefly explain me what s happening when I do this conversion

User · Answer

output   new ByteArrayOutputStream        input   new ByteArrayInputStream  output toByteArray

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byte   data   dbEntity getBlobData    response getOutputStream   write      I think this is better since you already have an existing OutputStream in the response object  no need to create a new OutputStream

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we can convert byte   array into input stream by using ByteArrayInputStream  String str    Welcome to awesome Java World       byte   content   str getBytes        int size   content length      InputStream is   null      byte   b   new byte size       is   new ByteArrayInputStream content     For full example please check here http   www onlinecodegeek com 2015 09 how-to-convert-byte-into-inputstream html

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I m assuming you mean that  use  means read  but what i ll explain for the read case can be basically reversed for the write case   so you end up with a byte    this could represent any kind of data which may need special types of conversions  character  encrypted  etc   let s pretend you want to write this data as is to a file   firstly you could create a ByteArrayInputStream which is basically a mechanism to supply the bytes to something in sequence   then you could create a FileOutputStream for the file you want to create  there are many types of InputStreams and OutputStreams for different data sources and destinations   lastly you would write the InputStream to the OutputStream  in this case  the array of bytes would be sent in sequence to the FileOutputStream for writing  For this i recommend using IOUtils  byte   bytes          ByteArrayInputStream in   new ByteArrayInputStream bytes   FileOutputStream out   new FileOutputStream new File        IOUtils copy in  out   IOUtils closeQuietly in   IOUtils closeQuietly out     and in reverse  FileInputStream in   new FileInputStream new File        ByteArrayOutputStream out   new ByteArrayOutputStream    IOUtils copy in  out   IOUtils closeQuietly in   IOUtils closeQuietly out   byte   bytes   out toByteArray      if you use the above code snippets you ll need to handle exceptions and i recommend you do the  closes  in a finally block

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There is no conversion between InputStream OutputStream and the bytes they are working with  They are made for binary data  and just read  or write  the bytes one by one as is   A conversion needs to happen when you want to go from byte to char  Then you need to convert using a character set  This happens when you make String or Reader from bytes  which are made for character data

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I do realize that my answer is way late for this question but I think the community would like a newer approach to this issue

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You create and use byte array I O streams as follows   byte   source        ByteArrayInputStream bis   new ByteArrayInputStream source      read bytes from bis      ByteArrayOutputStream bos   new ByteArrayOutputStream       write bytes to bos     byte   sink   bos toByteArray      Assuming that you are using a JDBC driver that implements the standard JDBC Blob interface  not all do   you can also connect a InputStream or OutputStream to a blob using the getBinaryStream and setBinaryStream methods1  and you can also get and set the bytes directly    In general  you should take appropriate steps to handle any exceptions  and close streams   However  closing bis and bos in the example above is unnecessary  since they aren t associated with any external resources  e g  file descriptors  sockets  database connections    1 - The setBinaryStream method is really a getter   Go figure

[java] Byte[] to InputStream or OutputStream

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