java实现rsa算法对文件加密解密，且完整提现生成公钥和私钥的过程，给出完整代码

以下是Java实现RSA算法对文件加密解密的完整代码：

import java.io.*;
import java.security.*;
import javax.crypto.*;

public class RSAFileEncryption {

    private static final int RSA_KEY_SIZE = 2048;

    public static void main(String[] args) throws Exception {
        // Generate public and private keys
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
        keyGen.initialize(RSA_KEY_SIZE);
        KeyPair keyPair = keyGen.generateKeyPair();
        PublicKey publicKey = keyPair.getPublic();
        PrivateKey privateKey = keyPair.getPrivate();
        System.out.println("Public key:\n" + publicKey);
        System.out.println("Private key:\n" + privateKey);

        // Write public and private keys to files
        ObjectOutputStream publicKeyOut = new ObjectOutputStream(new FileOutputStream("public.key"));
        publicKeyOut.writeObject(publicKey);
        publicKeyOut.close();
        ObjectOutputStream privateKeyOut = new ObjectOutputStream(new FileOutputStream("private.key"));
        privateKeyOut.writeObject(privateKey);
        privateKeyOut.close();

        // Encrypt file using public key
        File inputFile = new File("input.txt");
        File encryptedFile = new File("encrypted.txt");
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        FileInputStream inputStream = new FileInputStream(inputFile);
        FileOutputStream outputStream = new FileOutputStream(encryptedFile);
        byte[] inputBytes = new byte[(int) inputFile.length()];
        inputStream.read(inputBytes);
        byte[] encryptedBytes = cipher.doFinal(inputBytes);
        outputStream.write(encryptedBytes);
        inputStream.close();
        outputStream.close();

        // Decrypt file using private key
        File decryptedFile = new File("decrypted.txt");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        inputStream = new FileInputStream(encryptedFile);
        outputStream = new FileOutputStream(decryptedFile);
        byte[] encryptedBytes2 = new byte[(int) encryptedFile.length()];
        inputStream.read(encryptedBytes2);
        byte[] decryptedBytes = cipher.doFinal(encryptedBytes2);
        outputStream.write(decryptedBytes);
        inputStream.close();
        outputStream.close();
    }
}

在上面的代码中，我们使用`KeyPairGenerator`类生成公钥和私钥，然后将它们写入文件。我们使用`Cipher`类加密和解密文件。注意，我们使用RSA算法只是对文件进行加密和解密，而不是对文件内容进行数字签名。如果要进行数字签名，需要使用`Signature`类而不是`Cipher`类。