java代码实现rsa加密

可以用以下的Java代码来实现RSA加密：

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import javax.crypto.Cipher;

public class RSAEncryptor {
  private static final String ALGORITHM = "RSA";

  public static byte[] encrypt(byte[] data, PublicKey publicKey) throws Exception {
    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.ENCRYPT_MODE, publicKey);
    return cipher.doFinal(data);
  }

  public static byte[] decrypt(byte[] data, PrivateKey privateKey) throws Exception {
    Cipher cipher = Cipher.getInstance(ALGORITHM);
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    return cipher.doFinal(data);
  }

  public static KeyPair generateKeyPair() throws Exception {
    KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(ALGORITHM);
    keyPairGenerator.initialize(2048, new SecureRandom());
    return keyPairGenerator.generateKeyPair();
  }
}

使用方法如下：

// 生成密钥对
KeyPair keyPair = RSAEncryptor.generateKeyPair();
PrivateKey privateKey = keyPair.getPrivate();
PublicKey publicKey = keyPair.getPublic();

// 加密数据
String plaintext = "Hello, world!";
byte[] ciphertext = RSAEncryptor.encrypt(plaintext.getBytes(), publicKey);

// 解密数据
byte[] decryptedBytes = RSAEncryptor.decrypt(ciphertext, privateKey);
String decryptedPlaintext = new String(decryptedBytes);

System.out.println(decryptedPlaintext); // 输出："Hello, world!"

这段代码实现了RSA加密和解密的功能。您可以使用`RSAEncryptor.generateKeyPair()`方法生成公钥和私钥，使用`RSAEncryptor.encrypt(...)`方法加密数据，使用`RSAEncryptor.decrypt(...)`方法解密数据。