java PKCS7Padding 加密Cannot find any provider supporting AES/CBC/PKCS7Padding 解决办法

在java中用aes256进行加密，但是发现java里面不能使用PKCS7Padding，而java中自带的是PKCS5Padding填充，那解决办法是，通过BouncyCastle组件来让java里面支持PKCS7Padding填充。

首先，maven导入org.bouncycastle:bcprov-ext-jdk16:1.46到项目中

然后，照抄下方即可

注意：如果出现Illegal key size 报错问题，请点击此处

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Base64;

import java.io.UnsupportedEncodingException;
import java.security.Security;

import javax.crypto.*;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;


class test {
  static String encode(String keyString, String stringToEncode) {
      if (keyString == null || keyString.length() == 0) {
          throw new NullPointerException("Please give Password");
      }
      if (stringToEncode == null || stringToEncode.length() == 0) {
          throw new NullPointerException("Please give text");
      }
      try {
          SecretKeySpec skeySpec = getKey(keyString);
          byte[] clearText = stringToEncode.getBytes("UTF8");
          final byte[] iv = new byte[16];
          Arrays.fill(iv, (byte) 0x00);
          IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
          /**
             * 这个地方调用BouncyCastleProvider
             *让java支持PKCS7Padding
             */
          Security.addProvider(new BouncyCastleProvider());
          Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
          cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivParameterSpec);

          return new String(Base64.encode(cipher.doFinal(clearText)));

      } catch (Exception e) {
          e.printStackTrace();
      }
      return "";
  }

  static String decode(String password, String text) throws NullPointerException {
      if (password == null || password.length() == 0) {
          throw new NullPointerException("Please give Password");
      }
      if (text == null || text.length() == 0) {
          throw new NullPointerException("Please give text");
      }
      try {
          SecretKey key = getKey(password);
          final byte[] iv = new byte[16];
          Arrays.fill(iv, (byte) 0x00);
          IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
          /**
             * 这个地方调用BouncyCastleProvider
             *让java支持PKCS7Padding
             */
          Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
          Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
          cipher.init(Cipher.DECRYPT_MODE, key, ivParameterSpec);
          byte[] decrypedValueBytes = (cipher.doFinal(Base64.decode(text)));

          return new String(decrypedValueBytes);

      } catch (Exception e) {
          e.printStackTrace();
      }
      return "";
  }

  private static SecretKeySpec getKey(String password) throws UnsupportedEncodingException {
      int keyLength = 256;
      byte[] keyBytes = new byte[keyLength / 8];
      Arrays.fill(keyBytes, (byte) 0x0);

      byte[] passwordBytes = password.getBytes("UTF-8");
      int length = Math.min(passwordBytes.length, keyBytes.length);
      System.arraycopy(passwordBytes, 0, keyBytes, 0, length);
      return new SecretKeySpec(keyBytes, "AES");
  }

  public static void main(String args[]) {
      String encodeStr = encode("我是秘钥", "我是等待加密的文本");
      System.out.println("encoder:" + encodeStr);
      String decodeStr = decode("我是秘钥", encodeStr);
      System.out.println("decoder:" + decodeStr);

  }
}