一切福田，不離方寸，從心而覓，感無不通。

Category Archives: Programming Language

C#与java通过RSA互相加解密，支持分段加解密，支持长文本，支持公钥加密私钥解密，私钥加密公钥解密

1、C#代码 C#采用的RSACryptoServiceProvider类进行的加解密，由于该类默认是不支持私钥加密公钥解密的，需要通过BouncyCastle.Crypto.dll转换一下才可以。 代码如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Security;
using System.Xml;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.X509;
using Org.BouncyCastle.Asn1.X509;
namespace RSADemo
{
    /// <summary>
    /// RSA加解密帮助类
    /// 作者：代浩然
    /// 时间：2019-1-21 18:37
    /// </summary>
    public class RSAHelper
    {
        /// <summary>
        /// 生成公钥和私钥对
        /// </summary>
        public static void GeneratePublicAndPrivateKeyInfo()
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            using (StreamWriter writer = new StreamWriter("PrivateKey.xml"))  //这个文件要保密...
            {
                string privateKey = rsa.ToXmlString(true);
                writer.WriteLine(privateKey);
            }
            using (StreamWriter writer = new StreamWriter("PublicKey.xml"))
            {
                string publicKey = rsa.ToXmlString(false);
                writer.WriteLine(publicKey);
            }
        }
        /// <summary>
        /// 用私钥给数据进行RSA加密
        /// </summary>
        /// <param name="xmlPrivateKey"> 私钥(XML格式字符串)</param>
        /// <param name="strEncryptString">要加密的数据</param>
        /// <returns> 加密后的数据 </returns>
        public static string PrivateKeyEncrypt(string xmlPrivateKey, string strEncryptString)
        {
            //加载私钥
            RSACryptoServiceProvider privateRsa = new RSACryptoServiceProvider();
            privateRsa.FromXmlString(ReadFile(xmlPrivateKey));
            //转换密钥
            AsymmetricCipherKeyPair keyPair = DotNetUtilities.GetKeyPair(privateRsa);
            IBufferedCipher c = CipherUtilities.GetCipher("RSA/ECB/PKCS1Padding"); //使用RSA/ECB/PKCS1Padding格式
            //第一个参数为true表示加密，为false表示解密；第二个参数表示密钥
            c.Init(true, keyPair.Private);
            byte[] dataToEncrypt = Encoding.UTF8.GetBytes(strEncryptString);
            #region 分段加密
            int bufferSize = (privateRsa.KeySize / 8) - 11;
            byte[] buffer = new byte[bufferSize];
            byte[] outBytes = null;
            //分段加密
            using (MemoryStream input = new MemoryStream(dataToEncrypt))
            using (MemoryStream ouput = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, bufferSize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] encrypt = c.DoFinal(temp);
                    ouput.Write(encrypt, 0, encrypt.Length);
                }
                outBytes = ouput.ToArray();
            }
            #endregion
            //byte[] outBytes = c.DoFinal(DataToEncrypt);//加密
            string strBase64 = Convert.ToBase64String(outBytes);
            return strBase64;
        }
        /// <summary>
        /// 用公钥给数据进行RSA解密
        /// </summary>
        /// <param name="xmlPublicKey"> 公钥(XML格式字符串) </param>
        /// <param name="strDecryptString"> 要解密数据 </param>
        /// <returns> 解密后的数据 </returns>
        public static string PublicKeyDecrypt(string xmlPublicKey, string strDecryptString)
        {
            //加载公钥
            RSACryptoServiceProvider publicRsa = new RSACryptoServiceProvider();
            publicRsa.FromXmlString(ReadFile(xmlPublicKey));
            RSAParameters rp = publicRsa.ExportParameters(false);
            //转换密钥
            AsymmetricKeyParameter pbk = DotNetUtilities.GetRsaPublicKey(rp);
            IBufferedCipher c = CipherUtilities.GetCipher("RSA/ECB/PKCS1Padding");
            //第一个参数为true表示加密，为false表示解密；第二个参数表示密钥
            c.Init(false, pbk);
            byte[] outBytes = null;
            byte[] dataToDecrypt = Convert.FromBase64String(strDecryptString);
            #region 分段解密
            int keySize = publicRsa.KeySize / 8;
            byte[] buffer = new byte[keySize];
            using (MemoryStream input = new MemoryStream(dataToDecrypt))
            using (MemoryStream output = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, keySize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] decrypt = c.DoFinal(temp);
                    output.Write(decrypt, 0, decrypt.Length);
                }
                outBytes = output.ToArray();
            }
            #endregion
            //byte[] outBytes = c.DoFinal(DataToDecrypt);//解密
            string strDec = Encoding.UTF8.GetString(outBytes);
            return strDec;
        }
        /// <summary>
        /// 使用公钥加密，分段加密
        /// </summary>
        /// <param name="content"></param>
        /// <param name="privateKeyPath"></param>
        /// <returns></returns>
        public static string EncrytByPublic(string publicKeyPath, string strEncryptString)
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            rsa.FromXmlString(ReadFile(publicKeyPath));
            byte[] originalData = Encoding.UTF8.GetBytes(strEncryptString);
            if (originalData == null || originalData.Length <= 0)
            {
                throw new NotSupportedException();
            }
            if (rsa == null)
            {
                throw new ArgumentNullException();
            }
            byte[] encryContent = null;
            #region 分段加密
            int bufferSize = (rsa.KeySize / 8) - 11;
            byte[] buffer = new byte[bufferSize];
            //分段加密
            using (MemoryStream input = new MemoryStream(originalData))
            using (MemoryStream ouput = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, bufferSize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] encrypt = rsa.Encrypt(temp, false);
                    ouput.Write(encrypt, 0, encrypt.Length);
                }
                encryContent = ouput.ToArray();
            }
            #endregion
            return Convert.ToBase64String(encryContent);
        }
        /// <summary>
        /// 通过私钥解密，分段解密
        /// </summary>
        /// <param name="content"></param>
        /// <param name="privateKeyPath"></param>
        /// <returns></returns>
        public static string DecryptByPrivate(string privateKeyPath, string strDecryptString)
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            rsa.FromXmlString(ReadFile(privateKeyPath));
            byte[] encryptData = Convert.FromBase64String(strDecryptString);
            //byte[] dencryContent = rsa.Decrypt(encryptData, false);
            byte[] dencryContent = null;
            #region 分段解密
            if (encryptData == null || encryptData.Length <= 0)
            {
                throw new NotSupportedException();
            }
            int keySize = rsa.KeySize / 8;
            byte[] buffer = new byte[keySize];
            using (MemoryStream input = new MemoryStream(encryptData))
            using (MemoryStream output = new MemoryStream())
            {
                while (true)
                {
                    int readLine = input.Read(buffer, 0, keySize);
                    if (readLine <= 0)
                    {
                        break;
                    }
                    byte[] temp = new byte[readLine];
                    Array.Copy(buffer, 0, temp, 0, readLine);
                    byte[] decrypt = rsa.Decrypt(temp, false);
                    output.Write(decrypt, 0, decrypt.Length);
                }
                dencryContent = output.ToArray();
            }
            #endregion
            return Encoding.UTF8.GetString(dencryContent);
        }
        /// <summary>
        /// 读取文件
        /// </summary>
        /// <param name="filePath"></param>
        /// <returns></returns>
        public static string ReadFile(string filePath)
        {
            string content = "";
            if (File.Exists(filePath))
            {
                content = File.ReadAllText(filePath);
                byte[] mybyte = Encoding.UTF8.GetBytes(content);
                content = Encoding.UTF8.GetString(mybyte);
            }
            return content;
        }
        /// <summary>
        /// 将私钥转换成java所用的私钥字符串
        /// </summary>
        /// <param name="privateKeyPath">私钥文件路径</param>
        /// <returns></returns>
        public static string RSAPrivateKeyDotNet2Java(string privateKeyPath)
        {
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(ReadFile(privateKeyPath));
            BigInteger m = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Modulus")[0].InnerText));
            BigInteger exp = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Exponent")[0].InnerText));
            BigInteger d = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("D")[0].InnerText));
            BigInteger p = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("P")[0].InnerText));
            BigInteger q = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Q")[0].InnerText));
            BigInteger dp = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("DP")[0].InnerText));
            BigInteger dq = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("DQ")[0].InnerText));
            BigInteger qinv = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("InverseQ")[0].InnerText));
            RsaPrivateCrtKeyParameters privateKeyParam = new RsaPrivateCrtKeyParameters(m, exp, d, p, q, dp, dq, qinv);
            PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(privateKeyParam);
            byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetEncoded();
            return Convert.ToBase64String(serializedPrivateBytes);    
        }
        /// <summary>
        /// 将公钥转换成java所用的公钥字符串
        /// </summary>
        /// <param name="publicKeyPath">公钥路径</param>
        /// <returns></returns>
        public static string RSAPublicKeyDotNet2Java(string publicKeyPath)
        {
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(ReadFile(publicKeyPath));
            BigInteger m = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Modulus")[0].InnerText));
            BigInteger p = new BigInteger(1, Convert.FromBase64String(doc.DocumentElement.GetElementsByTagName("Exponent")[0].InnerText));
            RsaKeyParameters pub = new RsaKeyParameters(false, m, p);
            SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(pub);
            byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();
            return Convert.ToBase64String(serializedPublicBytes);
        }
    }
}

2、java端代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
import java.io.*;
import java.util.Base64;
public class Base64Utils {
    /** *//**
     * 文件读取缓冲区大小
     */
    private static final int CACHE_SIZE = 1024;
    /** *//**
     * <p>
     * BASE64字符串解码为二进制数据
     * </p>
     *
     * @param base64
     * @return
     * @throws Exception
     */
    public static byte[] decode(String base64) throws Exception {
        //return Base64.decode(base64.getBytes());
        //Base64.getEncoder().encodeToString("在Java 8中,Base64编码已经成为Java类库的标准。".getBytes("utf-8"));
        return Base64.getDecoder().decode(base64);
    }
    /** *//**
     * <p>
     * 二进制数据编码为BASE64字符串
     * </p>
     *
     * @param bytes
     * @return
     * @throws Exception
     */
    public static String encode(byte[] bytes) throws Exception {
        //return new String(Base64.encode(bytes));
        return Base64.getEncoder().encodeToString(bytes);
    }
    /** *//**
     * <p>
     * 将文件编码为BASE64字符串
     * </p>
     * <p>
     * 大文件慎用，可能会导致内存溢出
     * </p>
     *
     * @param filePath 文件绝对路径
     * @return
     * @throws Exception
     */
    public static String encodeFile(String filePath) throws Exception {
        byte[] bytes = fileToByte(filePath);
        return encode(bytes);
    }
    /** *//**
     * <p>
     * BASE64字符串转回文件
     * </p>
     *
     * @param filePath 文件绝对路径
     * @param base64 编码字符串
     * @throws Exception
     */
    public static void decodeToFile(String filePath, String base64) throws Exception {
        byte[] bytes = decode(base64);
        byteArrayToFile(bytes, filePath);
    }
    /** *//**
     * <p>
     * 文件转换为二进制数组
     * </p>
     *
     * @param filePath 文件路径
     * @return
     * @throws Exception
     */
    public static byte[] fileToByte(String filePath) throws Exception {
        byte[] data = new byte[0];
        File file = new File(filePath);
        if (file.exists()) {
            FileInputStream in = null;
            ByteArrayOutputStream out = null;
            try{
                in = new FileInputStream(file);
                out = new ByteArrayOutputStream(2048);
                byte[] cache = new byte[CACHE_SIZE];
                int nRead = 0;
                while ((nRead = in.read(cache)) != -1) {
                    out.write(cache, 0, nRead);
                    out.flush();
                }
                data = out.toByteArray();
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                if (in != null){
                    in.close();
                }
                if (out != null){
                    out.close();
                }
            }
        }
        return data;
    }
    /** *//**
     * <p>
     * 二进制数据写文件
     * </p>
     *
     * @param bytes 二进制数据
     * @param filePath 文件生成目录
     */
    public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {
        InputStream in = null;
        OutputStream out = null;
        try{
            in = new ByteArrayInputStream(bytes);
            File destFile = new File(filePath);
            if (!destFile.getParentFile().exists()) {
                destFile.getParentFile().mkdirs();
            }
            destFile.createNewFile();
            out = new FileOutputStream(destFile);
            byte[] cache = new byte[CACHE_SIZE];
            int nRead = 0;
            while ((nRead = in.read(cache)) != -1) {
                out.write(cache, 0, nRead);
                out.flush();
            }
            out.close();
            in.close();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (in != null){
                in.close();
            }
            if (out != null){
                out.close();
            }
        }
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.math.BigInteger;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.*;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;
/**
* 非对称加密解密
*/
public class RSAEncryptProvider {
    /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";
    /**
     * 签名算法
     */
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";
    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;
    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;
    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }
    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     *
     * @param msg 已加密数据
     * @param privateKey 私钥(BASE64编码)
     *
     * @return
     * @throws Exception
     */
    public static String sign(String msg, String privateKey) throws Exception {
        byte[] data = msg.getBytes();
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64.getEncoder().encodeToString(signature.sign());
    }
    /**
     * <p>
     * 校验数字签名
     * </p>
     *
     * @param msg 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     *
     * @return
     * @throws Exception
     *
     */
    public static boolean verify(String msg, String publicKey, String sign)
            throws Exception {
        byte[] data = msg.getBytes();
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64.getDecoder().decode(sign));
    }
    /**
     * <P>
     * 私钥解密，进行分片解密，解密大文本
     * </p>
     *
     * @param encryptedDataStr 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedDataStr, String privateKey)
            throws Exception {
        //byte[] encryptedData = Base64.getDecoder().decode(encryptedDataStr);
        byte[] encryptedData = encryptedDataStr;
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        //return new String(decryptedData);
        return decryptedData;
    }
    /**
     * <p>
     * 公钥解密，进行分片解密，解密大文本
     * </p>
     *
     * @param encryptedDataStr 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedDataStr, String publicKey)
            throws Exception {
        //byte[] encryptedData = Base64.getDecoder().decode(encryptedDataStr);
        byte[] encryptedData = encryptedDataStr;
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        //return new String(decryptedData);
        return decryptedData;
    }
    /**
     * <p>
     * 公钥加密，进行分片加密，加密大文本
     * </p>
     *
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        //String encryptedDataStr = Base64.getEncoder().encodeToString(encryptedData);
        return encryptedData;
    }
    /**
     * <p>
     * 私钥加密，进行分片加密，加密大文本
     * </p>
     *
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
            throws Exception {
        byte[] keyBytes = Base64.getDecoder().decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        //String encryptedDataStr = Base64.getEncoder().encodeToString(encryptedData);
        return encryptedData;
    }
    /**
     * <p>
     * 获取私钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }
    /**
     * <p>
     * 获取公钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }
    /**
     * 通过C#的RSACryptoServiceProvider类产生的公钥进行转换成java的公钥
     * @param modulus
     * @param exponent
     * @return
     */
    public static PublicKey getPublicKey(String modulus, String exponent) {
        try {
            byte[] m = Base64Utils.decode(modulus);
            byte[] e = Base64Utils.decode(exponent);
            BigInteger b1 = new BigInteger(1,m);
            BigInteger b2 = new BigInteger(1,e);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
            return (RSAPublicKey) keyFactory.generatePublic(keySpec);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    /**
     * 通过C#的RSACryptoServiceProvider类产生的私钥进行转换成java的私钥
     * @param modulus
     * @param privateExponent
     * @return
     */
    public PrivateKey getPrivateKey(String modulus,String privateExponent) throws Exception {
        BigInteger m = new BigInteger(modulus);
        BigInteger e = new BigInteger(privateExponent);
        RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(m,e);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }
    public static void main(String[] args) throws Exception {
        //通过C#公钥文件转换的java公钥字符串
        String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCYyiJ5biYwnsRE2RgqI6rEsmxySuoxRAKBPkxZwBN2+NTb4KNr8JUtaD8Fj+NV1+eEspm8MT519PJRwCxOGxf/qU3CqCnTwxoc3MrN3MwxeQ1FC2wZkEm8y8FZKWd84udULxML+7ao1bCYWeDerd2MBWvKBpEqoG28jY3yY1AGbQIDAQAB";
        //通过C#私钥文件转换的java私钥字符串
        String privateKey = "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";
        //公钥加密
        String data = testPublicEncrypt("abc12345555555555554444444444" +
                "4444444444444444444444444444444444444" +
                "44444444444444444444444444444444444444" +
                "44444444444444444444444444444444444444" +
                "44444444444444444444444444444444444" +
                "444444444444444444444444444444444444" +
                "444444444444444444444444444444444444" +
                "555555555555555555555555555555555" +
                "5555555555555555555555555555555",publicKey);
        System.out.println(data);
        //私钥解密
        data = testPrivateDencrypt(data,privateKey);
        System.out.println(data);
        //私钥加密
        data = testPrivateEncrypt("abc12345555555555554444444444" +
                "4444444444444444444444444444444444444" +
                "44444444444444444444444444444444444444" +
                "44444444444444444444444444444444444444" +
                "44444444444444444444444444444444444" +
                "444444444444444444444444444444444444" +
                "444444444444444444444444444444444444" +
                "555555555555555555555555555555555" +
                "5555555555555555555555555555555",privateKey);
        System.out.println(data);
        //公钥解密
        data = testPublicDecrypt(data,publicKey);
        System.out.println(data);
    }
    /**
     * 测试公钥加密
     * @param content 要加密的字符串
     * @return
     * @throws Exception
     */
    private static String testPublicEncrypt(String content,String publicKey)throws Exception{
        byte[] entryData = RSAEncryptProvider.encryptByPublicKey(content.getBytes("UTF-8"), publicKey);
        return Base64Utils.encode(entryData);
    }
    /**
     * 测试私钥解密
     * @param content
     * @return
     * @throws Exception
     */
    private static String testPrivateDencrypt(String content,String privateKey)throws Exception{
        byte[] dentryData = RSAEncryptProvider.decryptByPrivateKey(Base64Utils.decode(content),privateKey);
        return new String(dentryData,"UTF-8");
    }
    /**
     * 测试通过私钥加密
     * @param content
     * @param privateKey
     * @return
     * @throws Exception
     */
    private static String testPrivateEncrypt(String content,String privateKey)throws Exception{
        byte[] entryData = RSAEncryptProvider.encryptByPrivateKey(content.getBytes("UTF-8"), privateKey);
        return Base64Utils.encode(entryData);
    }
    /**
     * 测试通过公钥解密
     * @param content
     * @param publicKey
     * @return
     * @throws Exception
     */
    private static String testPublicDecrypt(String content,String publicKey)throws Exception{
        byte[] dentryData = RSAEncryptProvider.decryptByPublicKey(Base64Utils.decode(content),publicKey);
        return new String(dentryData,"UTF-8");
    }
}

代码下载地址：https://download.csdn.net/download/lengyue2015/10930794   from:https://blog.csdn.net/lengyue2015/article/details/86582177

龙生   09 Nov 2023
View Details

JDK动态代理(介绍理解，如何实现)

使用jdk的反射机制，创建对象的能力， 创建的是代理类的对象。 而不用你创建类文件。不用写java文件。
动态：在程序执行时，调用jdk提供的方法才能创建代理类的对象。

jdk动态代理，必须有接口，目标类必须实现接口， 没有接口时，需要使用cglib动态代理

龙生   08 Nov 2023
View Details

Java动态代理之一CGLIB详解

CGLIB(Code Generation Library)是一个开源、高性能、高质量的Code生成类库（代码生成包）。

它可以在运行期扩展Java类与实现Java接口。Hibernate用它实现PO(Persistent Object 持久化对象)字节码的动态生成，Spring AOP用它提供方法的interception（拦截）。

CGLIB的底层是通过使用一个小而快的字节码处理框架ASM，来转换字节码并生成新的类。但不鼓励大家直接使用ASM框架，因为对底层技术要求比较高。

龙生   08 Nov 2023
View Details

AspectJ入门

AOP的实现方式有两种：
AOP框架在编译阶段，就对目标类进行修改，得到的class文件已经是被修改过的。生成静态的AOP代理类（生成*.class文件已经被改掉了，需要使用特定的编译器）。以AspectJ为代表 —— 静态AOP框架。
AOP框架在运行阶段，动态生成AOP代理（在内存中动态地生成AOP代理类），以实现对目标对象的增强。它不需要特殊的编译器。以Spring AOP为代表。—— 动态AOP框架。

龙生   08 Nov 2023
View Details

SpringAOP学习--Spring事务简介及原理

事务简介
前篇介绍了SpringAOP，Spring事务是SpringAOP一个典型的应用。

事务即数据库事务，指同一批次对数据的读写要么全成功，要么全失败，用以保证数据的一致性，是关系统数据库核心功能。编程中通过设置事务手动提交，然后根据情况选择提交事务或者回滚事务。

数据库中事务使用:
BEGIN;#开始事务
update table_name set name=’XXX’ where id=’XXX’;#执行数据库操作
COMMIT; #提交
ROLLBACK;#回滚

龙生   08 Nov 2023
View Details

从HttpServletRequest中获取上传文件及参数的方法

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
try {
    //下面这句必须加，不然报错
    MultipartResolver resolver = new CommonsMultipartResolver(hsq.getSession().getServletContext());
    MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) hsq;
​
    //获取一起跟文件传过来的其他参数值
    String id = multipartRequest.getParameter("id");
​
    //获取上传上来的文件
    Map<String, MultipartFile> fileMap = multipartRequest.getFileMap();
    for (Map.Entry<String, MultipartFile> entry : fileMap.entrySet()) {
        MultipartFile file = entry.getValue();
        String fileName = file.getOriginalFilename();
        System.out.println(fileName);
        String path = "C:\\Users\\user\\Desktop\\" + fileName;
        file.transferTo(new File(path));
    }
} catch (Exception e) {
    e.printStackTrace();
}

  from:https://www.cnblogs.com/sanrenblog/p/15648871.html

龙生   06 Nov 2023
View Details

xhtmlrenderer 将html转换成pdf，完美css，带图片，手动分页，解决内容断开的问题

之前用itext7将html导出为pdf，比较方便，代码较少，而且支持base64的图片。但是itext7是收费的，所以换成了xhtmlrenderer。

xhtmlrenderer自动引入依赖包itext2.0.8，而且不能再引入其他版本的itext，因为itext2.0.8是已经被废弃的，里面的很多方法在新版本已经没有了。

龙生   02 Nov 2023
View Details

SHA256安全散列算法(JAVA)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
/**
* SHA256安全散列算法
*
* @author 冯龙生
*/
public class Sha256Util {
    /**
     * 安全散列算法摘要
     *
     * @param plainText 明文
     * @return 密文
     */
    public static String encrypt(String plainText) {
        MessageDigest messageDigest;
        String result = "";
 
        try {
            messageDigest = MessageDigest.getInstance("SHA-256");
            messageDigest.update(plainText.getBytes(StandardCharsets.UTF_8));
 
            result = byteToHex(messageDigest.digest());
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
 
        return result;
    }
 
    /**
     * 将byte转为16进制
     *
     * @param bytes 字节码
     * @return 16进制字符串
     */
    private static String byteToHex(byte[] bytes) {
        StringBuilder result = new StringBuilder();
        String temp;
 
        for (byte item : bytes) {
            temp = Integer.toHexString(item & 0xFF);
            if (temp.length() == 1) {
                result.append("0");
            }
 
            result.append(temp);
        }
 
        return result.toString();
    }
 
    public static void main(String[] args) {
        String sha256Str = encrypt("111111");
        System.out.println(sha256Str);
    }
}

 

龙生   01 Nov 2023
View Details

tkmybatis详细教程（一篇就明白）

tkmybatis 是对底层 sql 进行了抽象封装，不需要考虑 sql 怎么写，只需要按照逻辑思维，遵循 tkmybatis 的语法即可实现数据库操作。 本文适合对springboot项目结构有一定了解的读者。 本文的项目基础是一个demo项目（多模块的）。 1. 配置 1、添加 tkmybatis 的依赖

1
2
3
4
5
            <dependency>
                <groupId>tk.mybatis</groupId>
                <artifactId>mapper-spring-boot-starter</artifactId>
                <version>2.1.5</version>
            </dependency>

  2、创建 dao 层的 mapper 接口，每个接口都要继承  tk.mybatis.mapper.common.Mapper 接口。此接口的形式为 Mapper<T>，带了个泛型，此泛型一般指的是对应的 pojo 或者 domain。比如：

1
2
public interface HouseMapper extends Mapper<House> {
}

  3、在 Application 启动类上添加 mapper 扫描注解，表示要扫描到 dao 层的 mapper 接口。 比如本项目的mapper接口就统一放在 com.dgh.dao 下面，用 @MapperScan(basePackages = "包名") 来指定。 附注：在项目启动时，springboot 会自动扫描 Application 启动类所在的当前目录以及下一级目录，一般 Application 启动类都放在根目录，所以在单一项目下，只要是在 Java 类上添加了注解，都能够默认被 springboot 扫描到，并被添加到 springboot 的容器中，一般不需要特别用  @ComponentScan 去指定 springboot 要扫描哪些目录。 本文之所以特地用  @ComponentScan 去指定了 service 层和 controller 层的目录，是因为本文的项目是一个多模块项目，service 层和 controller 层各自都是一个独立的模块，与 Application 启动类不在同一目录下。

1
2
3
4
5
6
7
8
9
@SpringBootApplication
@MapperScan(basePackages = "com.dgh.dao")
@ComponentScan(basePackages = "com.dgh.service")
@ComponentScan(basePackages = "com.dgh.controller")
public class ControllerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ControllerApplication.class, args);
    }
}

4、tkmybatis 具体的使用是在 service 层，service 层又分为接口和接口实现类，具体就在接口实现类里面。 5、其它的代码、配置与普通的springboot项目一样。 2. tkmybatis的结构 下图是 tkmybatis 的结构图，圈中的是 Mapper 接口，是最底层的，也就意味着它继承了所有的功能。因此才有了 […]

龙生   30 Oct 2023
View Details

在Java中为日期增加一天的多种方法

一、用 plusDays() 方法将 Java 中的日期增加一天
二、用 Calendar 方法将 Java 中的日期增加一天
三、用 Milliseconds 方法将 Java 中的日期增加一天
四、用 Instant 类向 Java 日期添加一天

龙生   27 Oct 2023
View Details
1 … 17 18 19 … 175

Copyright © 2025 Longsheng All rights reserved