UnionId 是微信平台用户的唯一标识，对于后台开发来说，UnionId 无疑是一个非常好用的东西。

前言

在获取 UnionId 之前，首先需要做下面的准备：

在小程序平台完善自己的微信小程序信息

在微信开放平台将自己的微信小程序进行绑定

（在绑定小程序中使用的小程序账号就是上一步注册小程序时所用的账号/邮箱）

一、编写微信小程序前端代码

从 wx.getUserInfo接口文档 中可以知道，UnionId 被加密在wx.getUserInfo的回调函数返回值 encryptedData 中，所以我们只需要将 encryptedData 解密就可以获取到 UnionId 的值了。

1.编写 wxml button组件

编写 button 按钮且存在open-type="getUserInfo"属性，bindgetuserinfo 指定函数来接收回调函数返回值：

<view class="order_auth_wrap"><button type="primary" plain open-type="getUserInfo" bindgetuserinfo="handleGetUserInfo">获取授权</button></view>

2.编写 js 请求发送逻辑代码

在js代码中，我封装了wx.request接口函数，但是参数类型是相同的（其中 url 就是将encryptedData, iv, code发送到自己后台服务器进行解密的请求路径）：

import {login, request } from "../../utils/asyncWx.js";import regeneratorRuntime from '../../lib/runtime/runtime';//获取应用实例const app = getApp()Page({// 获取用户信息回调函数async handleGetUserInfo(e) {try {// 1.获取用户信息const {encryptedData, iv } = e.detail;// 2.获取小程序成功登陆后的codeconst {code } = await login();// 3.向后台发送 encryptedData, iv, code，后台通过解密之后获取 UserInfoconst params = {encryptedData, iv, code };const header = {'content-type': 'application/x-www-form-urlencoded' };const result = await request({url: "***", data: params, method: "POST", header });console.log(result);const {unionId } = result.data;// 4.将 unionId 保存到全局变量中app.globalData.unionId = unionId;// 5.跳转回上一层页面wx.navigateBack({delta: 1});} catch (error) {console.log(error);}}})

二、后台解密Controller实现

1.处理前端发送的 url 请求 controller：

package com.kiger.controller;import com.alibaba.fastjson.JSONObject;import com.kiger.Utils.AesCbcUtil;import com.kiger.Utils.HttpRequest;import com.monResult;import lombok.extern.slf4j.Slf4j;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import java.io.UnsupportedEncodingException;import java.util.HashMap;import java.util.Map;/*** @author zk_kiger* @date /4/18*/@RestController@Slf4j@RequestMapping("/api")public class ConsumerController {@PostMapping("/getUserInfo")public CommonResult<Map> getUserInfo(String encryptedData, String iv, String code) throws UnsupportedEncodingException {encryptedData = encryptedData.replaceAll(" ", "+");iv = iv.replaceAll(" ", "+");// 判断登录凭证不为空if (code == null || code.length() == 0) {return new CommonResult<>(0, "code 不能为空!");}// APPIdString appId = "wxacb2455649f74388";// AppSecretString appSecret = "3b49f7095369a48d33303c7d95c41ce5";// grant_type(固定内容)String grant_type = "authorization_code";// =================== 1.向微信服务器使用登录凭证 code 获取 session_key 和 openid ==============// 请求参数String params = "appid=" + appId + "&secret=" + appSecret + "&js_code=" + code + "&grant_type=" + grant_type;// 发送请求String res = HttpRequest.sendGet("https://api./sns/jscode2session", params);System.out.println("res: " + res);// 解析响应的内容转换为JSON对象JSONObject json = JSONObject.parseObject(res);//获取会话密钥（session_key）String session_key = json.get("session_key").toString();//用户的唯一标识（openid）String openid = (String) json.get("openid");// =================== 2.对encryptedData加密数据进行AES解密 ===================try {String result = AesCbcUtil.decrypt(encryptedData, session_key, iv, "UTF-8");System.out.println(result);if (result != null && result.length() > 0) {HashMap<String, Object> userInfoMap = new HashMap<>();JSONObject userInfo = JSONObject.parseObject(result);userInfoMap.put("openId", userInfo.get("openId"));userInfoMap.put("nickName", userInfo.get("nickName"));userInfoMap.put("gender", userInfo.get("gender"));userInfoMap.put("city", userInfo.get("city"));userInfoMap.put("province", userInfo.get("province"));userInfoMap.put("country", userInfo.get("country"));userInfoMap.put("avatarUrl", userInfo.get("avatarUrl"));userInfoMap.put("unionId", userInfo.get("unionId"));return new CommonResult<>(1, "解密成功!", userInfoMap);}} catch (Exception e) {e.printStackTrace();}return new CommonResult<>(0, "解密失败!");}}

需要注意：在接收参数之后，代码中对encryptedData和iv中字符串进行替换，这是因为在传输中，把原本的 ‘+’ 变为了 ‘ ’。

2.发送HTTP请求工具类

package com.kiger.Utils;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import .URL;import .URLConnection;import java.util.List;import java.util.Map;public class HttpRequest {/*** 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()));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;}/*** 向指定 URL 发送POST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 所代表远程资源的响应结果*/public static String sendPost(String url, String param) {PrintWriter out = null;BufferedReader in = null;String result = "";try {URL realUrl = new URL(url);// 打开和URL之间的连接URLConnection conn = realUrl.openConnection();// 设置通用的请求属性conn.setRequestProperty("accept", "*/*");conn.setRequestProperty("connection", "Keep-Alive");conn.setRequestProperty("user-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");// 发送POST请求必须设置如下两行conn.setDoOutput(true);conn.setDoInput(true);// 获取URLConnection对象对应的输出流out = new PrintWriter(conn.getOutputStream());// 发送请求参数out.print(param);// flush输出流的缓冲out.flush();// 定义BufferedReader输入流来读取URL的响应in = new BufferedReader(new InputStreamReader(conn.getInputStream()));String line;while ((line = in.readLine()) != null) {result += line;}} catch (Exception e) {System.out.println("发送 POST 请求出现异常！" + e);e.printStackTrace();}//使用finally块来关闭输出流、输入流finally {try {if (out != null) {out.close();}if (in != null) {in.close();}} catch (IOException ex) {ex.printStackTrace();}}return result;}}

3.AES解密工具类

package com.kiger.Utils;import mons.codec.binary.Base64;import org.bouncycastle.jce.provider.BouncyCastleProvider;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 java.io.UnsupportedEncodingException;import java.security.*;import java.security.spec.InvalidParameterSpecException;/*** Created by yfs on /2/6.* <p>* AES-128-CBC 加密方式* 注：* AES-128-CBC可以自己定义“密钥”和“偏移量“。* AES-128是jdk自动生成的“密钥”。*/public class AesCbcUtil {static {// BouncyCastle是一个开源的加解密解决方案，主页在/Security.addProvider(new BouncyCastleProvider());}/*** AES解密** @param data //密文，被加密的数据* @param key //秘钥* @param iv //偏移量* @param encodingFormat //解密后的结果需要进行的编码* @return* @throws Exception*/public static String decrypt(String data, String key, String iv, String encodingFormat) throws Exception {// 被加密的数据byte[] dataByte = Base64.decodeBase64(data);// 加密秘钥byte[] keyByte = Base64.decodeBase64(key);// 偏移量byte[] ivByte = Base64.decodeBase64(iv);try {Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");parameters.init(new IvParameterSpec(ivByte));cipher.init(Cipher.DECRYPT_MODE, spec, parameters);// 初始化byte[] resultByte = cipher.doFinal(dataByte);if (null != resultByte && resultByte.length > 0) {String result = new String(resultByte, encodingFormat);return result;}return null;} catch (NoSuchAlgorithmException e) {e.printStackTrace();} catch (NoSuchPaddingException e) {e.printStackTrace();} catch (InvalidParameterSpecException e) {e.printStackTrace();} catch (InvalidKeyException e) {e.printStackTrace();} catch (InvalidAlgorithmParameterException e) {e.printStackTrace();} catch (IllegalBlockSizeException e) {e.printStackTrace();} catch (BadPaddingException e) {e.printStackTrace();} catch (UnsupportedEncodingException e) {e.printStackTrace();}return null;}}

4.包装返回结果entities类

package com.kiger.entities;import lombok.AllArgsConstructor;import lombok.Data;import lombok.NoArgsConstructor;/*** @author zk_kiger* @date /4/17*/@Data@AllArgsConstructor@NoArgsConstructorpublic class CommonResult<T> {private Integer status;private String message;private T data;public CommonResult(Integer status, String message) {this(status, message, null);}}