Read a binary file in Java

Question

I have a java program that stores a byte array of 128 bytes length in a MySQL "BINARY (128)" field.

Then, with PHP I access to the database and I give the option to export this data into a file, so I unpack() the binary data, and write it into a file.

This file then, has to be read in a Java program that I am writing, but I can't find how I have to read this data. Any suggestion?

I tried with:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
int i = 0;
while (i < 128) {
  System.out.println(baos.read());
  i++;
}

But bis.read() returns an int, and the byte array I sent to the mysql db was a string: "text".getBytes("utf-8");

Thank you,

A ByteArrayOutputStream is only for outputting/writing. It doesn't have a read() method. — Peter Lawrey
– Peter Lawrey, Commented Mar 29, 2011 at 10:08

Peter Lawrey · Accepted Answer · 2011-03-29 10:14:25Z

1

To combine the answers of @Ricardo and @MarcoS

 DataInputStream dis = new DataInputStream(new FileInputStream("my-data-file.dat"));
 try {
     byte[] bytes = new byte[128];
     dis.readFully(bytes);
     // read some more.

 } finally {
     try {
        dis.close();
     } catch(IOException ignored) { }
 }

answered Mar 29, 2011 at 10:14

Peter Lawrey

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Ricardo Ferreira · Accepted Answer · 2011-03-29 10:07:52Z

1

Why don't you use a FileInputStream? (http://download.oracle.com/javase/1.4.2/docs/api/java/io/FileInputStream.html)

The read() method reads a byte, though it returns an int.

answered Mar 29, 2011 at 10:07

Ricardo Ferreira

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1 Comment

Peter Lawrey Over a year ago

+1: Best to use references to Java 6 Javadocs as both Java 1.4 and 5.0 are EOL now.

MarcoS · Accepted Answer · 2011-03-29 10:09:08Z

1

Have you tried with Data Streams?

answered Mar 29, 2011 at 10:09

MarcoS

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