Java实现RSA非对称加密工具类

RSA非对称加密通常运用于对字符串进行加密，通过密钥对（公钥、私钥）实现加密。

通过生成的公钥，对字符串加密后，得到一个加密的字符串，将私钥与这个加密后的字符串进行解密，得到原先的字符串。

补充：如果加密的字符串过长，会报错：javax.crypto.IllegalBlockSizeException: Data must not be longer than 117 byte

这里在文章后面补充两个方法用于解决超出117字节加密和126字节解密问题。

Java代码：

package com.vandet.indwebproject.utils;

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.UrlBase64;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import sun.misc.BASE64Decoder;
import sun.security.rsa.RSASignature;

import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.security.*;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;

import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import static com.vandet.indwebproject.test.Test2.KEY_ALGORITHM;

public class RSAUtils {

    private static final Logger LOGGER = LoggerFactory.getLogger(RSAUtils.class);
    public static final String KEY_ALGORITHM = "RSA";
    public static final String SIGNATURE_ALGORITHM = "SHA1WithRSA";
    public static final String ENCODING = "utf-8";
    public static final String X509 = "X.509";

    /**
     * 获取私钥
     *
     * @param key
     * @return
     * @throws Exception
     */
    public static PrivateKey getPrivateKey(Str