微信小程序解密*获取*unionid*java*

微信小程序获取unionId必须:
1.*注册微信开放平台,绑定需要获取unionid的应用。
2.*只是通过https://api.weixin.qq.com/sns/jscode2session
是永远拿不到unionId的只能拿session_key和openid,虽然官方说能拿到。


获取的流程:
*客户端(小程序)
wx.login ->      code
wx.userInfo -> iv(偏移量) , encryptedData(加密数据) 传给后台。

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Java服务端:

1.必须的依赖,用于解密过程。(或使用mvn加载)

   
    compile group: 'org.bouncycastle', name: 'bcprov-jdk15on', version: '1.59' 
    // https://mvnrepository.com/artifact/commons-codec/commons-codec
    compile group: 'commons-codec', name: 'commons-codec', version: '1.11'
    // https://mvnrepository.com/artifact/net.sf.json-lib/json-lib
    compile group: 'net.sf.json-lib', name: 'json-lib', version: '2.4'

AES工具类

package yourpkg;

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;
import org.apache.ofbiz.base.util.Debug;

public class AES {

    public static boolean initialized = false;
    public final static String module = AES.class.getName();
    /**
     * 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 {
            Debug.logInfo("content:"+content,module);
            Debug.logInfo("keyByte:"+keyByte,module);
            Debug.logInfo("ivByte:"+ivByte,module);
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
            Debug.logInfo("cipher:"+cipher,module);
            Key sKeySpec = new SecretKeySpec(keyByte, "AES");
            Debug.logInfo("sKeySpec:"+sKeySpec,module);
            cipher.init(Cipher.DECRYPT_MODE, sKeySpec, generateIV(ivByte));// 初始化

            byte[] result = cipher.doFinal(content);
            Debug.logInfo("result:"+result,module);
            return result;
        } catch (NoSuchAlgorithmException e) {
            Debug.logInfo("NoSuchAlgorithmException",module);
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            Debug.logInfo("NoSuchPaddingException",module);
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            Debug.logInfo("InvalidKeyException",module);

            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            Debug.logInfo("IllegalBlockSizeException",module);
            e.printStackTrace();
        } catch (BadPaddingException e) {
            Debug.logInfo("BadPaddingException",module);
            e.printStackTrace();
        } catch (NoSuchProviderException e) {
            Debug.logInfo("NoSuchProviderException",module);
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (Exception e) {
            Debug.logInfo("Exception",module);
            // 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;
    }

}

WX工具类

 
import org.apache.commons.codec.binary.Base64;
import net.sf.json.JSONObject;
import org.apache.ofbiz.base.util.Debug;
import org.apache.commons.codec.binary.Base64;

 
public class WXUtil {
 
    /**
     * 解密数据
     * @return
     * @throws Exception
     */
    public static String decrypt(String appId, String encryptedData, String sessionKey, String iv){
        String result = null;
        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);       
                return result;
            }
        } catch (Exception e) {
            result = "";
            e.printStackTrace();
        }
        return null;
    }
 
}

解密工具类

import java.nio.charset.Charset;
import java.util.Arrays;

 
public class WxPKCS7Encoder {
    private static final Charset CHARSET = Charset.forName("utf-8");
    private static final int BLOCK_SIZE = 32;

    /**
     * 获得对明文进行补位填充的字节.
     *
     * @param count
     *            需要进行填充补位操作的明文字节个数
     * @return 补齐用的字节数组
     */
    public static byte[] encode(int count) {
        // 计算需要填充的位数
        int amountToPad = BLOCK_SIZE - (count % BLOCK_SIZE);
        if (amountToPad == 0) {
            amountToPad = BLOCK_SIZE;
        }
        // 获得补位所用的字符
        char padChr = chr(amountToPad);
        String tmp = new String();
        for (int index = 0; index < amountToPad; index++) {
            tmp += padChr;
        }
        return tmp.getBytes(CHARSET);
    }

    /**
     * 删除解密后明文的补位字符
     *
     * @param decrypted
     *            解密后的明文
     * @return 删除补位字符后的明文
     */
    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);
    }

    /**
     * 将数字转化成ASCII码对应的字符，用于对明文进行补码
     *
     * @param a
     *            需要转化的数字
     * @return 转化得到的字符
     */
    public static char chr(int a) {
        byte target = (byte) (a & 0xFF);
        return (char) target;
    }
}

先通过code 拿 session_key ,这是解密的关键
WECHAT_MINI_PROGRAM_SNS_PATH:
https://api.weixin.qq.com/sns/jscode2session

        StringBuffer requestParamSB = new StringBuffer();

        requestParamSB.append("appid="+appId);//AK
        requestParamSB.append("&secret="+sc);//SC
        requestParamSB.append("&js_code="+code);//用户微信授权代码
        requestParamSB.append("&grant_type=authorization_code");//授予类型

        String responseStr = HttpRequestHelper.sendGet(SysConstant.WECHAT_MINI_PROGRAM_SNS_PATH, requestParamSB.toString());

HttpRequestHelper类

 import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.apache.http.HttpResponse;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import org.apache.http.HttpStatus;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicHeader;
import org.apache.http.protocol.HTTP;

import net.sf.json.JSONObject;

public class HttpRequestHelper {
/**
     * 向指定URL发送GET方法的请求
     *
     * @param url
     *            发送请求的URL
     * @param param
     *            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。
     * @return URL 所代表远程资源的响应结果
     */
    public static String sendGet(String url, String param) {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url + "?" + param;
            URL realUrl = new URL(urlNameString);
            // 打开和URL之间的连接
            URLConnection connection = realUrl.openConnection();
            // 设置通用的请求属性
            connection.setRequestProperty("accept", "*/*");
            connection.setRequestProperty("connection", "Keep-Alive");
            connection.setRequestProperty("user-agent",
                    "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
            // 建立实际的连接
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : map.keySet()) {
                System.out.println(key + "--->" + map.get(key));
            }
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(
                    connection.getInputStream(),"utf-8"));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            System.out.println("发送GET请求出现异常！" + e);
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }
}

然后将这些值传入方法即可,appId可以不要,只是起到校验作用。

WXUtil.decrypt(appId,encryptedData,sessionKey,iv);


微信反馈结果格式:

{"openId":"ofql75ZdllClk7lnuc4","nickName":"Xxx","gender":1,"language":"zh_CN","city":"new york","province":"ina","country":"gogx","avatarUrl":"https://wx.qlogo.cn/mmopen/vi_a2/Q0j4TwGTfTJgWxRlibYMHfVdjCDqibj8lfTch1hwzl2CvcmficSvS2sZh1icXrQhwJlCFS4LwknHd3F7FWfnxg/1d2","unionId":"opDl4wlzx_QrxyN4vxm1A","watermark":{"timestamp":154222947163,"appid":"wxc3asdr3v5b32b3531f3a"}}

注意:

当你无法解密或者解密出的结果为空时,（或者出现pad block corrupted 报错)
请友善提示前端同学,可能是他的问题。

参考: 微信小程序解密encryptedData 报错：pad block corrupted 解决方法https://blog.csdn.net/l523115401/article/details/80251859