BufferedInputStream class

java.lang.Object
 |
 +-java.io.InputStream
     |
     +-java.io.FilterInputStream
         |
         +-java.io.BufferedInputStream

Java's BufferedInputStream class allows you to "wrap" any InputStream into a buffered stream and achieve this performance improvement.

BufferedInputStream has two constructors:

BufferedInputStream(InputStream inputStream) creates a buffered stream using a default buffer size. BufferedInputStream(InputStream inputStream, int bufSize) the size of the buffer is passed in bufSize.

A BufferedInputStream adds the ability to buffer the input and to support the mark and reset methods.

When the BufferedInputStream is created, an internal buffer array is created.

Constructor

BufferedInputStream(InputStream in)

Creates a BufferedInputStream and saves its argument, the input stream in, for later use.

BufferedInputStream(InputStream in, int size)

Creates a BufferedInputStream with the specified buffer size, and saves its argument, the input stream in, for later use.

int available()

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.

void close()

Closes this input stream and releases any system resources associated with the stream.

void mark(int readlimit)

See the general contract of the mark method of InputStream.

boolean markSupported()

Tests if this input stream supports the mark and reset methods.

int read()

See the general contract of the read method of InputStream.

int read(byte[] b, int off, int len)

Reads bytes from this byte-input stream into the specified byte array, starting at the given offset.

void reset()

See the general contract of the reset method of InputStream.

long skip(long n)

See the general contract of the skip method of InputStream.

Revised from Open JDK source code

Create BufferedInputStream from FileInputStream

import java.io.BufferedInputStream;
import java.io.FileInputStream;

public class Main {

  public static void main(String args[]) throws Exception {
    FileInputStream fis = new FileInputStream("c:/a.htm");

    BufferedInputStream bis = new BufferedInputStream(fis);

    int i;
    while ((i = bis.read()) != -1) {
      System.out.println(i);
    }

    fis.close();
  }
}

Read byte array out of BufferedInputStream

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;

public class Main {

  public static void main(String[] args) throws Exception {
    File file = new File("C:/ReadFile.txt");
    FileInputStream fin = new FileInputStream(file);
    BufferedInputStream bin = new BufferedInputStream(fin);

    byte[] contents = new byte[1024];
    int bytesRead = 0;
    String strFileContents;
    while ((bytesRead = bin.read(contents)) != -1) {
      strFileContents = new String(contents, 0, bytesRead);
      System.out.print(strFileContents);
    }
    bin.close();
  }
}