ByteArrayInputStream is an implementation of an InputStream that uses a byte array as the source.
This class has two constructors, each of which requires a byte array to provide the data source:
ByteArrayInputStream(byte array[ ])
array is the input source.
ByteArrayInputStream(byte array[ ], int start, int numBytes)
uses a subset of your byte array.
Methods from ByteArrayInputStream
int available()
Returns the number of remaining bytes that can be read (or skipped over) from this input stream.
void close()
Closing a ByteArrayInputStream has no effect.
void mark(int readAheadLimit)
Set the current marked position in the stream.
boolean markSupported()
If this InputStream supports mark/reset.
int read()
Reads the next byte of data.
int read(byte[] b, int off, int len)
Reads up to len bytes of data into an array of bytes from this input stream.
void reset()
Resets the buffer to the marked position.
long skip(long n)
Skips n bytes of input from this input stream.
Revised from Open JDK source code
Create ByteArrayInputStream from byte array
import java.io.ByteArrayInputStream;
import java.io.IOException;
public class Main {
public static void main(String args[]) throws IOException {
String tmp = "abcdefghijklmnopqrstuvwxyz";
byte b[] = tmp.getBytes();
ByteArrayInputStream input1 = new ByteArrayInputStream(b);
ByteArrayInputStream input2 = new ByteArrayInputStream(b, 0, 3);
}
}
A ByteArrayInputStream implements both mark( ) and reset( ). The following example uses the reset( ) method to read the same input twice.
import java.io.ByteArrayInputStream;
import java.io.IOException;
public class Main {
public static void main(String args[]) throws IOException {
String tmp = "abc";
byte b[] = tmp.getBytes();
ByteArrayInputStream in = new ByteArrayInputStream(b);
for (int i = 0; i < 2; i++) {
int c;
while ((c = in.read()) != -1) {
if (i == 0) {
System.out.print((char) c);
} else {
System.out.print(Character.toUpperCase((char) c));
}
}
System.out.println();
in.reset();
}
}
}
The following code reads byte array out of ByteArrayInputStream
import java.io.ByteArrayInputStream;
import java.io.IOException;
public class Main {
public static void main(String args[]) throws IOException {
ByteArrayInputStream inStream = new ByteArrayInputStream(("rntsoft.com").getBytes());
int inBytes = inStream.available();
System.out.println("inStream has " + inBytes + " available bytes");
byte inBuf[] = new byte[inBytes];
int bytesRead = inStream.read(inBuf, 0, inBytes);
System.out.println(bytesRead + " bytes were read");
System.out.println("They are: " + new String(inBuf));
}
}
The output:
inStream has 10 available bytes
10 bytes were read
They are: rntsoft.com