File file = new File("filename.bin");
byte[] fileData = new byte[file.length()];
FileInputStream in = new FileInputStream(file);
in.read(fileData):
in.close();
// now fileData contains the bytes of the file
String content = "";
for(byte b : fileData)
content += getBits(b);
// content now contains your bits.
String getBits(byte b)
{
String result = "";
for(int i = 0; i < 8; i++)
result += (b & (1 << i)) == 0 ? "0" : "1";
return result;
}