Input Stream is ...
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int next = in.read();
while (next > -1) {
    bos.write(next);
    next = in.read();
}
bos.flush();
byte[] result = bos.toByteArray();
bos.close();

Input Stream is ...
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int next = in.read();
while (next > -1) {
    bos.write(next);
    next = in.read();
}
bos.flush();
byte[] result = bos.toByteArray();
bos.close();

/*InputStream class_InputStream = null;
I am reading class from DB 
class_InputStream = rs.getBinaryStream(1);
Your Input stream could be from any source
*/
int thisLine;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while ((thisLine = class_InputStream.read()) != -1) {
    bos.write(thisLine);
}
bos.flush();
byte [] yourBytes = bos.toByteArray();

/*Don't forget in the finally block to close ByteArrayOutputStream & InputStream
 In my case the IS is from resultset so just closing the rs will do it*/

if (bos != null){
    bos.close();
}

Java 7及以上版本:

import sun.misc.IOUtils;
...
InputStream in = ...;
byte[] buf = IOUtils.readFully(in, -1, false);

使用普通Java的DataInputStream和它的readFully方法(至少从Java 1.4开始存在):

...
byte[] bytes = new byte[(int) file.length()];
DataInputStream dis = new DataInputStream(new FileInputStream(file));
dis.readFully(bytes);
...

这个方法还有其他一些形式，但在这个用例中，我一直使用这个方法。

你可以试试仙人掌:

byte[] array = new BytesOf(stream).bytes();