package examples;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

import java.nio.file.*;

public class NIOExample3 {

public static void main(String[] args) {

try {

// Test Encrypted File Transfer

NIOFileOperations.encryptDecryptFile("original.bin", "encrypted.bin", (byte) 0x5A);

NIOFileOperations.encryptDecryptFile("encrypted.bin", "decrypted.bin", (byte) 0x5A);

// Test Merging Large Files

NIOFileOperations.mergeFiles("merged.bin", "file1.bin", "file2.bin", "file3.bin");

// Test Custom Serialization

NIOFileOperations.serialize("data.bin", "Anirudha Gaikwad", 30, 55000.50);

NIOFileOperations.deserialize("data.bin");

// Test Byte-Level File Compression

NIOFileOperations.compress("input.bin", "compressed.bin");

NIOFileOperations.decompress("compressed.bin", "decompressed.bin");

// Test Partial File Read & Write

NIOFileOperations.readAndWriteRange("large.bin", "partial.bin", 1024, 4096);

} catch (IOException e) {

e.printStackTrace();

}

}

}

class NIOFileOperations {

/**

* Encrypted File Transfer:

* Reads a binary file, encrypts its content using XOR cipher,

* and writes it to another file. This method can also decrypt.

*/

public static void encryptDecryptFile(String inputFile, String outputFile, byte xorKey) throws IOException {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ);

FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {

ByteBuffer buffer = ByteBuffer.allocate(8192);

while (inChannel.read(buffer) > 0) {

buffer.flip();

for (int i = 0; i < buffer.limit(); i++) {

buffer.put(i, (byte) (buffer.get(i) ^ xorKey)); // XOR encryption/decryption

}

outChannel.write(buffer);

buffer.clear();

}

}

}

/**

* Merging Large Binary Files:

* Merges multiple large binary files into a single file efficiently.

*/

public static void mergeFiles(String outputFile, String... inputFiles) throws IOException {

try (FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {

ByteBuffer buffer = ByteBuffer.allocate(8192);

for (String inputFile : inputFiles) {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ)) {

while (inChannel.read(buffer) > 0) {

buffer.flip();

outChannel.write(buffer);

buffer.clear();

}

}

}

}

}

/**

* Custom Serialization:

* Saves and retrieves an object's data using FileChannel instead of ObjectOutputStream.

*/

public static void serialize(String outputFile, String name, int age, double salary) throws IOException {

try (FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {

ByteBuffer buffer = ByteBuffer.allocate(128);

buffer.putInt(name.length());

buffer.put(name.getBytes());

buffer.putInt(age);

buffer.putDouble(salary);

buffer.flip();

outChannel.write(buffer);

}

}

public static void deserialize(String inputFile) throws IOException {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ)) {

ByteBuffer buffer = ByteBuffer.allocate(128);

inChannel.read(buffer);

buffer.flip();

int nameLength = buffer.getInt();

byte[] nameBytes = new byte[nameLength];

buffer.get(nameBytes);

String name = new String(nameBytes);

int age = buffer.getInt();

double salary = buffer.getDouble();

System.out.println("Deserialized: " + name + ", Age: " + age + ", Salary: " + salary);

}

}

/**

* Byte-Level File Compression (Run-Length Encoding - RLE):

* Compresses and decompresses a file using basic RLE.

*/

public static void compress(String inputFile, String outputFile) throws IOException {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ);

FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {

ByteBuffer buffer = ByteBuffer.allocate(8192);

inChannel.read(buffer);

buffer.flip();

ByteBuffer compressed = ByteBuffer.allocate(8192);

byte prev = buffer.get();

int count = 1;

while (buffer.hasRemaining()) {

byte curr = buffer.get();

if (curr == prev && count < 255) {

count++;

} else {

compressed.put((byte) count);

compressed.put(prev);

prev = curr;

count = 1;

}

}

compressed.put((byte) count);

compressed.put(prev);

compressed.flip();

outChannel.write(compressed);

}

}

public static void decompress(String inputFile, String outputFile) throws IOException {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ);

FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {

ByteBuffer buffer = ByteBuffer.allocate(8192);

inChannel.read(buffer);

buffer.flip();

ByteBuffer decompressed = ByteBuffer.allocate(8192);

while (buffer.hasRemaining()) {

int count = buffer.get() & 0xFF;

byte value = buffer.get();

for (int i = 0; i < count; i++) {

decompressed.put(value);

}

}

decompressed.flip();

outChannel.write(decompressed);

}

}

/**

* Partial File Read & Write:

* Reads a specific byte range from a file and writes it to another file.

*/

public static void readAndWriteRange(String inputFile, String outputFile, long start, long end) throws IOException {

try (FileChannel inChannel = FileChannel.open(Paths.get(inputFile), StandardOpenOption.READ);

FileChannel outChannel = FileChannel.open(Paths.get(outputFile), StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {

inChannel.position(start);

long size = Math.min(end - start, inChannel.size() - start);

ByteBuffer buffer = ByteBuffer.allocate((int) size);

inChannel.read(buffer);

buffer.flip();

outChannel.write(buffer);

}

}

}