byte[] to file in Java

Question

With Java:

I have a byte[] that represents a file.

How do I write this to a file (ie. C:\myfile.pdf)

I know it's done with InputStream, but I can't seem to work it out.

Answer 1

////////////////////////// 1] File to Byte [] ///////////////////

Path path = Paths.get(p);
                    byte[] data = null;                         
                    try {
                        data = Files.readAllBytes(path);
                    } catch (IOException ex) {
                        Logger.getLogger(Agent1.class.getName()).log(Level.SEVERE, null, ex);
                    }

/////////////////////// 2] Byte [] to File ///////////////////////////

 File f = new File(fileName);
 byte[] fileContent = msg.getByteSequenceContent();
Path path = Paths.get(f.getAbsolutePath());
                            try {
                                Files.write(path, fileContent);
                            } catch (IOException ex) {
                                Logger.getLogger(Agent2.class.getName()).log(Level.SEVERE, null, ex);
                            }

Answer 2

I know it's done with InputStream

Actually, you'd be writing to a file output...

Answer 3

You can try Cactoos:

new LengthOf(new TeeInput(array, new File("a.txt"))).value();

More details: http://www.yegor256.com/2017/06/22/object-oriented-input-output-in-cactoos.html

Answer 4

Try an OutputStream or more specifically FileOutputStream

Answer 5

This is a program where we are reading and printing array of bytes offset and length using String Builder and Writing the array of bytes offset length to the new file.

`Enter code here

import java.io.File;   
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;        

//*This is a program where we are reading and printing array of bytes offset and length using StringBuilder and Writing the array of bytes offset length to the new file*//     

public class ReadandWriteAByte {
    public void readandWriteBytesToFile(){
        File file = new File("count.char"); //(abcdefghijk)
        File bfile = new File("bytefile.txt");//(New File)
        byte[] b;
        FileInputStream fis = null;              
        FileOutputStream fos = null;          

        try{               
            fis = new FileInputStream (file);           
            fos = new FileOutputStream (bfile);             
            b = new byte [1024];              
            int i;              
            StringBuilder sb = new StringBuilder();

            while ((i = fis.read(b))!=-1){                  
                sb.append(new String(b,5,5));               
                fos.write(b, 2, 5);               
            }               

            System.out.println(sb.toString());               
        }catch (IOException e) {                    
            e.printStackTrace();                
        }finally {               
            try {              
                if(fis != null);           
                    fis.close();    //This helps to close the stream          
            }catch (IOException e){           
                e.printStackTrace();              
            }            
        }               
    }               

    public static void main (String args[]){              
        ReadandWriteAByte rb = new ReadandWriteAByte();              
        rb.readandWriteBytesToFile();              
    }                 
}                

O/P in console : fghij

O/P in new file :cdefg

Answer 6

Without any libraries:

try (FileOutputStream stream = new FileOutputStream(path)) {
    stream.write(bytes);
}

With Google Guava:

Files.write(bytes, new File(path));

With Apache Commons:

FileUtils.writeByteArrayToFile(new File(path), bytes);

All of these strategies require that you catch an IOException at some point too.