BufferedInputStream into byte[] to be send over a Socket to a Database

Question

I have been looking around for an answer to this, but couldn't really find anything on it. Earlier today, I asked how I could make a File into a String through a byte array, and then back again, for retrieval later. What people told me, was that I had to just store the byte array, to avoid nasty encoding issues. So now I've started working on that, but I have now hit a wall. Basically, I used unbuffered streams before, to turn a file into a byte array. This works good in theory, but it takes up a lot of memory which eventually will cast the heap size exception. I should use buffered streams instead (or so I am told), and the problem I have now, is going from a BufferedInputStream to a byte[]. I've tried to copy and use the methods found in this documentation http://docs.guava-libraries.googlecode.com/git/javadoc/index.html?com/google/common/io/package-summary.html Where I exchange unbuffered streams for buffered streams. The only issue, is that I can't directly turn a buffered output…

Accepted Answer

Have a look at ByteArrayOutputStream: Java 7 API java.io.ByteArrayOutputStream

```
bytesOut = new ByteArrayOutputStream();
byte[] bytes = bytesOut.toByteArray();
```

Update: If you insist on doing what you are doing you can just assign the intermediate ByteArrayOutputStream to a variable and get hold of the array that way:

```
ByteArrayOutputStream bytesOut = new ByteArrayOutputStream()
BufferedOutputStream out = new BufferedOutputStream(bytesOut);
copy(in, out);
return bytesOut.toByteArray();
```

Update 2: The real question seems to be how to copy a file without reading it all into memory first:

1) Manually:

```
    byte[] buff = new byte[64*1024]; //or some size, can try out different sizes for performance
    BufferedInputStream in = new BufferedInputStream(new FileInputStream("fromFile"));
    BufferedOutputStream out = new BufferedOutputStream(new FileoutputStream("toFile"));
    int n = 0;
    while ((n = in.read(buff)) >= 0) {
        out.write(buff, 0, n);
    }
    in.close();
    out.close();
```

2) Efficiently by the OS and no loop etc:

```
FileChannel from = new FileInputStream(sourceFile).getChannel();
FileChanngel to = new FileOutputStream(destFile).getChannel();
to.transferFrom(from, 0, from.size());
//or from.transferTo(0, from.size(), to);
from.close();
to.close();
```

3) If you have Java 7 you can simplify exception and stream closing or just copy the file with the new APIs i in java 7:

```
java.nio.file.Files.copy(...);
```

see java.nio.file.Files

BufferedInputStream into byte[] to be send over a Socket to a Database

Solution

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