<dependency>
 <groupId>org.bouncycastle</groupId>
 <artifactId>bcprov-jdk16</artifactId>
 <version>1.46</version>
</dependency>
 
 <dependency>
 <groupId>commons-codec</groupId>
 <artifactId>commons-codec</artifactId>
 <version>1.4</version>
</dependency>
 
<dependency> 
 <groupId>net.sf.json-lib</groupId> 
 <artifactId>json-lib</artifactId> 
 <version>2.2.3</version> 
 <classifier>jdk15</classifier> 
</dependency>

package com.chwl.medical.crypto.wx;
 
import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;
 
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
 
/**
 * AES加密
 * @author liuyazhuang
 *
 */
public class AES {
 
 public static boolean initialized = false;
 
 /**
 * AES解密
 * 
 * @param content
 *  密文
 * @return
 * @throws InvalidAlgorithmParameterException
 * @throws NoSuchProviderException
 */
 public byte[] decrypt(byte[] content, byte[] keyByte, byte[] ivByte) throws InvalidAlgorithmParameterException {
 initialize();
 try {
 Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
 Key sKeySpec = new SecretKeySpec(keyByte, "AES");
 cipher.init(Cipher.DECRYPT_MODE, sKeySpec, generateIV(ivByte));// 初始化
 byte[] result = cipher.doFinal(content);
 return result;
 } catch (NoSuchAlgorithmException e) {
 e.printStackTrace();
 } catch (NoSuchPaddingException e) {
 e.printStackTrace();
 } catch (InvalidKeyException e) {
 e.printStackTrace();
 } catch (IllegalBlockSizeException e) {
 e.printStackTrace();
 } catch (BadPaddingException e) {
 e.printStackTrace();
 } catch (NoSuchProviderException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } catch (Exception e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 return null;
 }
 
 public static void initialize() {
 if (initialized)
 return;
 Security.addProvider(new BouncyCastleProvider());
 initialized = true;
 }
 
 // 生成iv
 public static AlgorithmParameters generateIV(byte[] iv) throws Exception {
 AlgorithmParameters params = AlgorithmParameters.getInstance("AES");
 params.init(new IvParameterSpec(iv));
 return params;
 }
}

package com.chwl.medical.crypto.wx;
 
import java.nio.charset.Charset;
import java.util.Arrays;
 
 
/**
 * 微信小程序加解密
 * @author liuyazhuang
 *
 */
public class WxPKCS7Encoder {
 private static final Charset CHARSET = Charset.forName("utf-8");
 private static final int BLOCK_SIZE = 32;
 
 /**
 * 獲得對明文進行補位填充的字節(jié).
 *
 * @param count
 *  需要進行填充補位操作的明文字節(jié)個數(shù)
 * @return 補齊用的字節(jié)數(shù)組
 */
 public static byte[] encode(int count) {
 // 計算需要填充的位數(shù)
 int amountToPad = BLOCK_SIZE - (count % BLOCK_SIZE);
 if (amountToPad == 0) {
 amountToPad = BLOCK_SIZE;
 }
 // 獲得補位所用的字符
 char padChr = chr(amountToPad);
 String tmp = new String();
 for (int index = 0; index < amountToPad; index++) {
 tmp += padChr;
 }
 return tmp.getBytes(CHARSET);
 }
 
 /**
 * 刪除解密后明文的補位字符
 *
 * @param decrypted
 *  解密后的明文
 * @return 刪除補位字符后的明文
 */
 public static byte[] decode(byte[] decrypted) {
 int pad = decrypted[decrypted.length - 1];
 if (pad < 1 || pad > 32) {
 pad = 0;
 }
 return Arrays.copyOfRange(decrypted, 0, decrypted.length - pad);
 }
 
 /**
 * 將數(shù)字轉化成ASCII碼對應的字符，用于對明文進行補碼
 *
 * @param a
 *  需要轉化的數(shù)字
 * @return 轉化得到的字符
 */
 public static char chr(int a) {
 byte target = (byte) (a & 0xFF);
 return (char) target;
 }
}

package com.chwl.medical.crypto.wx;
 
import org.apache.commons.codec.binary.Base64;
 
import net.sf.json.JSONObject;
 
 
/**
 * 封裝對外訪問方法
 * @author liuyazhuang
 *
 */
public class WXCore {
 
 private static final String WATERMARK = "watermark";
 private static final String APPID = "appid";
 /**
 * 解密數(shù)據(jù)
 * @return
 * @throws Exception
 */
 public static String decrypt(String appId, String encryptedData, String sessionKey, String iv){
 String result = "";
 try {
 AES aes = new AES(); 
 byte[] resultByte = aes.decrypt(Base64.decodeBase64(encryptedData), Base64.decodeBase64(sessionKey), Base64.decodeBase64(iv)); 
 if(null != resultByte && resultByte.length > 0){ 
  result = new String(WxPKCS7Encoder.decode(resultByte)); 
 JSONObject jsonObject = JSONObject.fromObject(result);
 String decryptAppid = jsonObject.getJSONObject(WATERMARK).getString(APPID);
 if(!appId.equals(decryptAppid)){
 result = "";
 }
  } 
 } catch (Exception e) {
 result = "";
 e.printStackTrace();
 }
 return result;
 }
 
 
 public static void main(String[] args) throws Exception{
 String appId = "wx4f4bc4dec97d474b";
 String encryptedData = "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";
 String sessionKey = "tiihtNczf5v6AKRyjwEUhQ==";
 String iv = "r7BXXKkLb8qrSNn05n0qiA==";
 System.out.println(decrypt(appId, encryptedData, sessionKey, iv));
 }
}