public class WechatUtil {
    public static JSONObject getSessionKeyOrOpenId(String code) {
        String requestUrl = "https://api.weixin.qq.com/sns/jscode2session";
        Map<String, String> requestUrlParam = new HashMap<>();
        // https://mp.weixin.qq.com/wxopen/devprofile?action=get_profile&token=164113089&lang=zh_CN
        //小程序appId
        requestUrlParam.put("appid", WXConstant.APPID);
        //小程序secret
        requestUrlParam.put("secret", WXConstant.SECRET);
        //小程序端返回的code
        requestUrlParam.put("js_code", code);
        //默認(rèn)參數(shù)
        requestUrlParam.put("grant_type", "authorization_code");
        //發(fā)送post請(qǐng)求讀取調(diào)用微信接口獲取openid用戶唯一標(biāo)識(shí)
        JSONObject jsonObject = JSON.parseObject(HttpClientUtil.doPost(requestUrl, requestUrlParam));
        return jsonObject;
    }
}

<!-- http請(qǐng)求工具包依賴 -->
<dependency>
	<groupId>org.apache.httpcomponents</groupId>
	<artifactId>httpclient</artifactId>
	<version>4.5.2</version>
</dependency>

public class HttpClientUtil {

    public static String doGet(String url, Map<String, String> param) {

        // 創(chuàng)建Httpclient對(duì)象
        CloseableHttpClient httpclient = HttpClients.createDefault();

        String resultString = "";
        CloseableHttpResponse response = null;
        try {
            // 創(chuàng)建uri
            URIBuilder builder = new URIBuilder(url);
            if (param != null) {
                for (String key : param.keySet()) {
                    builder.addParameter(key, param.get(key));
                }
            }
            URI uri = builder.build();

            // 創(chuàng)建http GET請(qǐng)求
            HttpGet httpGet = new HttpGet(uri);

            // 執(zhí)行請(qǐng)求
            response = httpclient.execute(httpGet);
            // 判斷返回狀態(tài)是否為200
            if (response.getStatusLine().getStatusCode() == 200) {
                resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (response != null) {
                    response.close();
                }
                httpclient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return resultString;
    }

    public static String doGet(String url) {
        return doGet(url, null);
    }

    public static String doPost(String url, Map<String, String> param) {
        // 創(chuàng)建Httpclient對(duì)象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String resultString = "";
        try {
            // 創(chuàng)建Http Post請(qǐng)求
            HttpPost httpPost = new HttpPost(url);
            // 創(chuàng)建參數(shù)列表
            if (param != null) {
                List<NameValuePair> paramList = new ArrayList<>();
                for (String key : param.keySet()) {
                    paramList.add(new BasicNameValuePair(key, param.get(key)));
                }
                // 模擬表單
                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList);
                httpPost.setEntity(entity);
            }
            // 執(zhí)行http請(qǐng)求
            response = httpClient.execute(httpPost);
            resultString = EntityUtils.toString(response.getEntity(), "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                response.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return resultString;
    }

    public static String doPost(String url) {
        return doPost(url, null);
    }

    public static String doPostJson(String url, String json) {
        // 創(chuàng)建Httpclient對(duì)象
        CloseableHttpClient httpClient = HttpClients.createDefault();
        CloseableHttpResponse response = null;
        String resultString = "";
        try {
            // 創(chuàng)建Http Post請(qǐng)求
            HttpPost httpPost = new HttpPost(url);
            // 創(chuàng)建請(qǐng)求內(nèi)容
            StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
            httpPost.setEntity(entity);
            // 執(zhí)行http請(qǐng)求
            response = httpClient.execute(httpPost);
            resultString = EntityUtils.toString(response.getEntity(), "utf-8");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                response.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return resultString;
    }
}

@PostMapping("/wx/login")
public R user_login(@RequestParam(value = "code", required = false) String code,
                    @RequestParam(value = "rawData", required = false) String rawData,
                    @RequestParam(value = "signature", required = false) String signature) {
    // 用戶非敏感信息：rawData
    // 簽名：signature
    JSONObject rawDataJson = JSON.parseObject(rawData);
    // 1.接收小程序發(fā)送的code
    // 2.開發(fā)者服務(wù)器 登錄憑證校驗(yàn)接口 appi + appsecret + code
    JSONObject SessionKeyOpenId = WechatUtil.getSessionKeyOrOpenId(code);
    // 3.接收微信接口服務(wù) 獲取返回的參數(shù)
    String openid = SessionKeyOpenId.getString("openid");
    String sessionKey = SessionKeyOpenId.getString("session_key");

    // 4.校驗(yàn)簽名 小程序發(fā)送的簽名signature與服務(wù)器端生成的簽名signature2 = sha1(rawData + sessionKey)
    String signature2 = DigestUtils.sha1Hex(rawData + sessionKey);
    if (!signature.equals(signature2)) {
        return R.error().message("簽名校驗(yàn)失敗");
    }
    // 5.根據(jù)返回的User實(shí)體類，判斷用戶是否是新用戶，是的話，將用戶信息存到數(shù)據(jù)庫(kù)；
    LambdaQueryWrapper<User> lqw = Wrappers.lambdaQuery();
    lqw.eq(User::getOpenId, openid);
    User user = userService.getOne(lqw);
    if (user == null) {
        // 用戶信息入庫(kù)
        String nickName = rawDataJson.getString("nickName");
        String avatarUrl = rawDataJson.getString("avatarUrl");
        user = new User();
        user.setOpenId(openid);
        user.setAvatar(avatarUrl);
        user.setNickName(nickName);
        userService.save(user);
    }
    return R.ok().data(user);
}