问将字符串私钥转换为PrivateKey类型

EN

String privatekey = -----BEGIN RSA PRIVATE KEY-----
MIIEpAIBAAKCAQEAqAKCCMKqboM8ywSuNvmf2zuT0e2elxntdEe5msv22jzT89Xa
1Q/V4CeQdZruIw8eTAMa67Dej+3cPdSrjdDnfxcb9L14U9oFPgOyvxVwb+/S8jqm
F9o7Gvm85X972C8izh+K4ndpPtztxkZ0g7cu7RqrCCBzw5SUfi3pgIpprdiKlVDP
4lF7CTwzRH+oi+BxwOABEiuKOJtjOXX1WJhV6ukEy8K6Fq/QOyt/7vgxkm8I8HMo
SMq2UZNswn5/9SqMWuaTBaQbjZ2f77zaq5X/jOiCThTxFNPjPnzhKhG8ekaqIUpB
y9VuICFgdtVQimnlDykrdJWyeOFWPjYl5vehkwIDAQABAoIBAQCN2Ig2ozvHUA/s
i8gWbAyVyKgVrhueEOrUqJXAZoHEYWTFUgGOru7wcBbb4/E4MlRu8pQw90QAml6+
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s6w9ZFQ/JKvPka6LKo9wNI0W1EVC2tggN0Jt6YJFU7trb5TtiQm/B4NKpflZ7PsC
1WOttz0q+VSzF/p04+33OLXugF1crgMr9KCg0uSPi5zCcM+3RVSWDrcZoh+yV4pK
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3PoxB7CxAoGBANkK9ITnfIr1AlF8S1Ok12AlHLYvCPG4TVBw4WNVUX1y3wBXpOmx
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RfsxvWVQpzvCVH4yV+tkH107ivR2uFDtbDjqlydPyIxmA1Frlm87CODpAoGBAMYq
gLO5EEKxs1MlCzZkuqsEAq+kZVX7y3Kw9rzCJtRQKfYu0IlNFudPg3KpqcbQsrfR
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Dwc9+Xrc6ydcDtTHAi3JeIReEbDMvFc6JRiyjwEbAoGAeH68gYyCeCLNxq9aonVB
nP79kadLL+dCBQamGp+jPiIn6+i8hYFEiitrZ5xC500yDvvsvuRbmtb6Yw1xCgkv
Mp7P5xb1puKPJlrH6AXAyDGRJD0/7ych8vMKUtUUAvlAL0+DwAs13mzQGChQ65zk
GDUk9Y41qLx52xn/yoDbzQECgYEAksM9qF1iPpLPBcAEqtc1LJz+xEiTyHeAOMP5
KNj92vY37ZzEUzulv9AywQQIujcsdVlRTGPLIk8APlpo3K/p3kt7vlkedbRSk3vZ
09YtNo5wOJTk4ThQ9bhNwlF5rrOOxBZnUuzCTQ06l17lmQ5+fZydxiLJJVCsGEn2
2XC82osCgYB9maZnLrSZ3Xq4X256/H+Et8TcgqOZGbLuGkNzheheP/E5LcUhQqbP
oJRB24XoX+yw+Do5q2pHHgbrrHwcdg3Xfw9sb5P2JNbtG57mO7QEilIHfUQzQl/U
XSKgJJZ/9bTPlbZmp9ChM9izUv8DI5vjhDputhlEHP4BpHBN03a85Q==
-----END RSA PRIVATE KEY-----

  public PrivateKey generatePrivateKey(String privateKey) throws Exception{

        privateKey = privateKey.replace("-----BEGIN RSA PRIVATE KEY-----", "");
        privateKey = privateKey.replace("-----END RSA PRIVATE KEY-----", "");
        privateKey = privateKey.replaceAll("\\s+", "");
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKey.getBytes());
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(keySpec);
    }

Execution exception[[InvalidKeySpecException: java.security.InvalidKeyException: invalid key format]]

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Base64;

public class pkcs1ToPkcs8 {

    public static void main(String[] args) throws IOException {

        String pkcs1 = //privatekey provided above

            // b64 now contains the base64 "body" of the PEM-PKCS#1 file
            byte[] oldder = Base64.getDecoder().decode(pkcs1.getBytes());

            // concatenate the mostly-fixed prefix plus the PKCS#1 data 
            final byte[] prefix = {0x30,(byte)0x82,0,0, 2,1,0, // SEQUENCE(lenTBD) and version INTEGER 
                    0x30,0x0d, 6,9,0x2a,(byte)0x86,0x48,(byte)0x86,(byte)0xf7,0x0d,1,1,1, 5,0, // AlgID for rsaEncryption,NULL
                    4,(byte)0x82,0,0 }; // OCTETSTRING(lenTBD) 
            byte[] newder = new byte [prefix.length + oldder.length];
            System.arraycopy (prefix,0, newder,0, prefix.length);
            System.arraycopy (oldder,0, newder,prefix.length, oldder.length);
            // and patch the (variable) lengths to be correct
            int len = oldder.length, loc = prefix.length-2; 
            newder[loc] = (byte)(len>>8); newder[loc+1] = (byte)len;
            len = newder.length-4; loc = 2;
            newder[loc] = (byte)(len>>8); newder[loc+1] = (byte)len;

            FileOutputStream fo = new FileOutputStream ("pkcs8_file");
            fo.write (newder); fo.close();
            System.out.println ("converted length " + newder.length);

    }

}