试了一下午终于跑通了，一开始尝试RC4算法生成的密文在java中解密不出来，放弃了，改用AES。

js代码

import aes from 'crypto-js/aes';
import base from 'crypto-js/enc-base64';function encrypt(plaintext: string) {const iv = base.parse('ZGYyMzRzZDIzNDEyMzU2Zw==');const key = base.parse('ZGYyMzRzZGRzYWVxZWZ2ZA==');// 如果.toString()改成.ciphertext.toString()，则java解密时要使用HexUtil.decode，否则使用BASE64Util.decodereturn aes.encrypt(plaintext, key, {iv: iv}).toString();}

java代码

import com.google.api.client.repackaged.org.apache.commons.codec.binary.Base64;import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;/*** AES工具类，密钥必须是16位字符串*/
public class AESUtils {/**偏移量,必须是16位字符串*/private static final String IV_STRING = "df234sd23412356g";/*** 默认的密钥*/public static final String DEFAULT_KEY = "df234sddsaeqefvd";public static String encryptData(String content) {byte[] encryptedBytes = null;try {byte[] byteContent = content.getBytes("UTF-8");// 注意，为了能与 iOS 统一// 这里的 key 不可以使用 KeyGenerator、SecureRandom、SecretKey 生成byte[] enCodeFormat = DEFAULT_KEY.getBytes();SecretKeySpec secretKeySpec = new SecretKeySpec(enCodeFormat, "AES");byte[] initParam = IV_STRING.getBytes();IvParameterSpec ivParameterSpec = new IvParameterSpec(initParam);// 指定加密的算法、工作模式和填充方式Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);encryptedBytes = cipher.doFinal(byteContent);// 同样对加密后数据进行 base64 编码String encodeStr = BASE64Util.encode(encryptedBytes);
//            String encodeStr = HexUtil.encode(encryptedBytes);encodeStr = encodeStr.replace("%","%25").replace("&","%26").replace("+","%2B");return encodeStr;
//            return parseByte2HexStr(encryptedBytes);} catch (Exception e) {e.printStackTrace();}return null;}public static String decryptData(String content) {try {content = content.replace("%25","%").replace("%26","&").replace("%2B","+");// base64 解码byte[] encryptedBytes = BASE64Util.decode(content);
//        	byte[] encryptedBytes = HexUtil.decode(content);
//        	byte[] encryptedBytes = parseHexStr2Byte(content);byte[] enCodeFormat = DEFAULT_KEY.getBytes();SecretKeySpec secretKey = new SecretKeySpec(enCodeFormat, "AES");byte[] initParam = IV_STRING.getBytes();IvParameterSpec ivParameterSpec = new IvParameterSpec(initParam);Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameterSpec);byte[] result = cipher.doFinal(encryptedBytes);return new String(result, "UTF-8");} catch (Exception e) {e.printStackTrace();}return null;}public static void main(String[] args) {byte[] bytes = IV_STRING.getBytes();String base64Str = Base64.encodeBase64String(bytes);// js 中的iv用这个base64StrSystem.out.println(base64Str);bytes = DEFAULT_KEY.getBytes();base64Str = Base64.encodeBase64String(bytes);// js 中的key用这个base64StrSystem.out.println(base64Str);System.out.println("用户加密"+AESUtils.encryptData("《湖北省能源发展“十四五”规划》提出，适度超前推进充电础基设施建设，到2025年全省充电桩达到50万个以上。"));System.out.println("用户解密"+AESUtils.decryptData("HYezy8lsT3ql6uAZxm/7vBCZAI0kxUpvny9tJLRbMJg/Mr4dCalEqC19z8Yl21tEuEdzGWTqTjIASOqx/FL+XimSZt1seFUpJrJ5E/2XorWwFZNMXKSURFdw8wV7savQJbVaTwZuJ4yML6ok1VwQ8y8yAqmr0TG38FLovyfEhQcVVOx0+UmQdsOLpERuYQDE9Pw216beyhml1BZNDhC91Q=="));}}

上面用到的BASE64Util.decode为

	public static byte[] decode(String base64str) throws Exception { //byte[] b=base64str.getBytes();Base64 base64=new Base64();b=base64.decode(b);return b;}

HexUtil.decode为

    public static byte[] decode(String src) {int m = 0, n = 0;int byteLen = src.length() / 2;byte[] ret = new byte[byteLen];for (int i = 0; i < byteLen; i++) {m = i * 2 + 1;n = m + 1;int intVal = Integer.decode("0x" + src.substring(i * 2, m) + src.substring(m, n));ret[i] = Byte.valueOf((byte)intVal);}return ret;}