一切福田，不離方寸，從心而覓，感無不通。

Category Archives: Java

Java获得当前日期是星期几

第一种方法：

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/**
* 获取当前日期是星期几<br>
*
* @param date
* @return 当前日期是星期几
*/
public String getWeekOfDate(Date date) {
String[] weekDays = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int w = cal.get(Calendar.DAY_OF_WEEK) - 1;
if (w < 0)
w = 0;
return weekDays[w];
}

  第二种方法： 使用SimpleDateFormat格式化日期

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Date date = new Date();
SimpleDateFormat dateFm = new SimpleDateFormat("EEEE");
String currSun = dateFm.format(date);
System.out.println(currSun);

  注：格式化字符串存在区分大小写 对于创建SimpleDateFormat传入的参数：EEEE代表星期，如“星期四”；MMMM代表中文月份，如“七月”；MM代表月份，如“07”；yyyy代表年份，如“2017”；dd代表天，如“05” from:https://blog.csdn.net/u013456370/article/details/74373410

龙生   27 Nov 2023
View Details

Java Xmll转Json工具类

先看效果： xml

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<?xml version="1.0" encoding="utf-8" ?>
<auibinsurancecallback>
<policyinfo>
<transtype>TKTS</transtype>
<eticketno>xxx</eticketno>
<flightnumber>xxx</flightnumber>
<flightdate>2019-10-16</flightdate>
<operatetime>2019-10-16 17:20:00</operatetime>
<insureno>1910161720056066735</insureno>
<agreeno>102160199</agreeno>
<policyno/>
<policyurl><![CDATA[]]></policyurl>
</policyinfo>
<returninfo>
<serialnumber>2019103015284949545354</serialnumber>
<retruncode>0</retruncode>
<errormessage><![CDATA[]]></errormessage>
</returninfo>
<list>
<item>
<name>john</name>
<age>22</age>
<log>
<record>1</record>
<record>2</record>
</log>
</item>
<item>
<name>lucy</name>
<age>23</age>
<log>
<record>
<id>1</id>
<event>event1</event>
</record>
<record>
<id>2</id>
<event>event2</event>
</record>
</log>
</item>
</list>
<list2>
<item>
<name>lily</name>
<age>24</age>
</item>
</list2>
</auibinsurancecallback>

  json

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{
"auibinsurancecallback": {
"policyinfo": {
"transtype": "TKTS",
"eticketno": "xxx",
"flightnumber": "xxx",
"flightdate": "2019-10-16",
"operatetime": "2019-10-16 17:20:00",
"insureno": "1910161720056066735",
"agreeno": "102160199",
"policyno": "",
"policyurl": ""
},
"returninfo": {
"serialnumber": "2019103015284949545354",
"retruncode": "0",
"errormessage": ""
},
"list": {
"item": [
{
"name": "john",
"age": "22",
"log": {
"record": [
{
"record": "1"
},
{
"record": "2"
}
]
}
},
{
"name": "lucy",
"age": "23",
"log": {
"record": [
{
"id": "1",
"event": "event1"
},
{
"id": "2",
"event": "event2"
}
]
}
}
]
},
"list2": {
"item": {
"name": "lily",
"age": "24"
}
}
}
}

  依赖

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        <!-- https://mvnrepository.com/artifact/org.dom4j/dom4j -->
        <dependency>
            <groupId>org.dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>2.1.4</version>
        </dependency>
 
        <!-- https://mvnrepository.com/artifact/com.alibaba.fastjson2/fastjson2 -->
        <dependency>
            <groupId>com.alibaba.fastjson2</groupId>
            <artifactId>fastjson2</artifactId>
            <version>2.0.42</version>
        </dependency>

  代码

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package org.longsheng.util;
 
import com.alibaba.fastjson2.JSONArray;
import com.alibaba.fastjson2.JSONObject;
import lombok.extern.slf4j.Slf4j;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
 
import java.util.ArrayList;
import java.util.List;
 
/**
* Xml转JSON工具包
*/
@Slf4j
public class XmlToJsonUtil {
    /**
     * 转换为json字符串
     *
     * @param xmlString xml字符串
     * @return json字符串
     */
    public static String toJsonString(String xmlString) {
        JSONObject result = toJson(xmlString);
        if (result == null) {
            return null;
        }
 
        return result.toString();
    }
 
    /**
     * 转换为json对象
     *
     * @param xmlString xml字符串
     * @return json对象
     */
    public static JSONObject toJson(String xmlString) {
        try {
            Document doc = DocumentHelper.parseText(xmlString);
            return toJson(doc);
        } catch (DocumentException e) {
            log.error("{}===>{}===>exception: {} | {}", Thread.currentThread().getStackTrace()[1].getClassName(), Thread.currentThread().getStackTrace()[1].getMethodName(), e.getMessage(), e.getStackTrace());
        }
 
        return null;
    }
 
    /**
     * 转换为json对象
     *
     * @param document xml对象
     * @return json对象
     */
    public static JSONObject toJson(Document document) {
        if (document == null) {
            return null;
        }
 
        try {
            Element root = document.getRootElement();
            List<Element> elements = root.elements();
 
            JSONObject jsonObject = new JSONObject();
            jsonObject.put(root.getName(), elementToJson(elements));
 
            return jsonObject;
        } catch (Exception e) {
            log.error("{}===>{}===>exception: {} | {}", Thread.currentThread().getStackTrace()[1].getClassName(), Thread.currentThread().getStackTrace()[1].getMethodName(), e.getMessage(), e.getStackTrace());
        }
 
        return null;
    }
 
    /**
     * 递归读取节点，并简单判定节点状态（值、对象、列表三种状态）
     *
     * @param elements
     * @return
     */
    public static JSONObject elementToJson(List<Element> elements) {
        if (elements == null || elements.isEmpty()) {
            return null;
        }
 
        JSONObject result = new JSONObject();
 
        // single object
        if (elements.size() == 1) {
            Element element = elements.get(0);
            List<Element> children = element.elements();
            result.put(element.getName(), children.isEmpty() ? element.getText() : elementToJson(children));
 
            return result;
        }
 
        // multi-object
        if (!elements.get(0).getName().equals(elements.get(1).getName())) {
            result.clear();
            List<Element> children;
 
            for (Element element : elements) {
                children = element.elements();
                result.put(element.getName(), children.isEmpty() ? element.getText() : elementToJson(children));
            }
 
            return result;
        }
 
        // array list
        List<JSONObject> jsonList = new ArrayList<>();
        List<Element> children;
        for (Element element : elements) {
            children = element.elements();
            result = new JSONObject();
 
            if (children.isEmpty()) {
                result.put(element.getName(), element.getText());
            } else {
                result = elementToJson(children);
            }
 
            jsonList.add(result);
        }
        result = new JSONObject();
        result.put(elements.get(0).getName(), jsonList);
        return result;
    }
 
    /**
     * 从json对象中获取指定名称的json数组
     *
     * @param jsonObject json对象
     * @param nodeName json数组节点名称
     * @return json数组
     */
    public static JSONArray getArray(JSONObject jsonObject, String nodeName) {
        if (jsonObject == null || nodeName == null || nodeName.isEmpty()) {
            return null;
        }
 
        Object node = jsonObject.get(nodeName);
        if (node == null) {
            return null;
        }
 
        JSONArray result = new JSONArray();
        if (node instanceof JSONObject) {
            result.add(node);
            return result;
        }
 
        if (node instanceof ArrayList) {
            result = jsonObject.getJSONArray(nodeName);
        }
 
        return result;
    }
 
    public static void main(String[] args) {
        String xml = "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n" +
                "<auibinsurancecallback>\n" +
                "\t<policyinfo>\n" +
                "\t\t<transtype>TKTS</transtype>\n" +
                "\t\t<eticketno>xxx</eticketno>\n" +
                "\t\t<flightnumber>xxx</flightnumber>\n" +
                "\t\t<flightdate>2019-10-16</flightdate>\n" +
                "\t\t<operatetime>2019-10-16 17:20:00</operatetime>\n" +
                "\t\t<insureno>1910161720056066735</insureno>\n" +
                "\t\t<agreeno>102160199</agreeno>\n" +
                "\t\t<policyno/>\n" +
                "\t\t<policyurl><![CDATA[]]></policyurl>\n" +
                "\t</policyinfo>\n" +
                "\t<returninfo>\n" +
                "\t\t<serialnumber>2019103015284949545354</serialnumber>\n" +
                "\t\t<retruncode>0</retruncode>\n" +
                "\t\t<errormessage><![CDATA[]]></errormessage>\n" +
                "\t</returninfo>\n" +
                "\t<list>\n" +
                "\t\t<item>" +
                "\t\t\t<name>john</name>" +
                "\t\t\t<age>22</age>" +
                "\t\t\t<log>" +
                "\t\t\t\t<record>1</record>" +
                "\t\t\t\t<record>2</record>" +
                "\t\t\t</log>" +
                "\t\t</item>\n" +
                "\t\t<item>" +
                "\t\t\t<name>lucy</name>" +
                "\t\t\t<age>23</age>" +
                "\t\t\t<log>" +
                "\t\t\t\t<record>" +
                "\t\t\t\t\t<id>1</id>" +
                "\t\t\t\t\t<event>event1</event>" +
                "\t\t\t\t</record>" +
                "\t\t\t\t<record>" +
                "\t\t\t\t\t<id>2</id>" +
                "\t\t\t\t\t<event>event2</event>" +
                "\t\t\t\t</record>" +
                "\t\t\t</log>" +
                "\t\t</item>\n" +
                "\t</list>\n" +
                "\t<list2>\n" +
                "\t\t<item>" +
                "\t\t\t<name>lily</name>" +
                "\t\t\t<age>24</age>" +
                "\t\t</item>\n" +
                "\t</list2>\n" +
                "</auibinsurancecallback>";
 
        JSONObject json = toJson(xml);
 
        System.out.println(xml);
        System.out.println();
        assert json != null;
        System.out.println(json.toJSONString());
 
        JSONArray array1 = getArray(json.getJSONObject("auibinsurancecallback").getJSONObject("list"), "item");
        JSONArray array2 = getArray(json.getJSONObject("auibinsurancecallback").getJSONObject("list2"), "item");
        System.out.println();
        System.out.println(array1.toJSONString());
        System.out.println(array2.toJSONString());
    }
}

 

龙生   24 Nov 2023
View Details

Spring Boot 2.7.15集成Nacos 2.2.3

依赖

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// https://mvnrepository.com/artifact/com.alibaba.boot/nacos-config-spring-boot-starter
implementation group: 'com.alibaba.boot', name: 'nacos-config-spring-boot-starter', version: '0.2.12'

  配置文件 application.yml

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nacos:
  config:
    server-addr: 127.0.0.1:8848
    username: xxxx
    password: xxxxxx

  注解 @NacosPropertySource

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@SpringBootApplication
@MapperScan("com.w3cnet.xxx.repository")
@NacosPropertySource(dataId = "xxx-prod.yml", autoRefreshed = true)
public class XxxxApplication {
 
public static void main(String[] args) {
SpringApplication.run(XxxxApplication.class, args);
}
 
}

  注解 @NacosValue

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    @NacosValue(value = "${xxx.url}", autoRefreshed = true)
    private String xxxUrl;

  参考资料：https://nacos.io/zh-cn/docs/quick-start-spring-boot.html

龙生   12 Nov 2023
View Details

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：

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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

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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();
            }
        }
    }
}

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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
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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
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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
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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
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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
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从HttpServletRequest中获取上传文件及参数的方法

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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
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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
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