微信登录，返回 js 签名给前端

 /**
     * 获取登录信息
     * @param url 输入的 url
     * @return
     */
    @GetMapping("/ouath/url")
    public Result<?> jumpToApp(@RequestParam(defaultValue = "",required = false) String url) {

        Result data = Result.success(
                appUtil.getMapDataForH5(url)
        );
        return data;
    }

package top.hundreds.homeworkhelper.util;

import com.alibaba.fastjson.JSONObject;
import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.impl.client.DefaultHttpClient;
import org.springframework.stereotype.Component;
import top.hundreds.homeworkhelper.config.WxMaProperties;

import javax.annotation.Resource;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

/**
 * @Author lyr
 * @create 2020/10/8 15:59
 */
@Component
public class AppUtil {


    public String getAccessToken(String appId, String appSecret) {
        // 网页授权接口
        String GetPageAccessTokenUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=" + appId + "&secret=" + appSecret;

        HttpClient client = null;
        String access_token = null;
        int expires_in = 0;
        try {
            client = new DefaultHttpClient();
            HttpGet httpget = new HttpGet(GetPageAccessTokenUrl);
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            String response = client.execute(httpget, responseHandler);
            JSONObject OpenidJSONO = JSONObject.parseObject(response);
            access_token = String.valueOf(OpenidJSONO.get("access_token"));//获取access_token
            expires_in = Integer.parseInt(String.valueOf(OpenidJSONO.get("expires_in")));//获取时间
        } catch (Exception e) {
            throw new RuntimeException("获取AccessToken出错！");
        } finally {
            client.getConnectionManager().shutdown();
        }
        return access_token;

    }

    public String getTicket(String accessToken) {
        // 网页授权接口
        String GetPageAccessTokenUrl = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=" + accessToken + "&type=jsapi";
        HttpClient client = null;
        String ticket = "";
        int expires_in = 0;
        try {
            client = new DefaultHttpClient();
            HttpGet httpget = new HttpGet(GetPageAccessTokenUrl);
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            String response = client.execute(httpget, responseHandler);
            JSONObject OpenidJSONO = JSONObject.parseObject(response);
            ticket = String.valueOf(OpenidJSONO.get("ticket"));//获取ticket
            expires_in = Integer.parseInt(String.valueOf(OpenidJSONO.get("expires_in")));//获取时间
        } catch (Exception e) {
            throw new RuntimeException("获取Ticket出错！");
        } finally {
            client.getConnectionManager().shutdown();
        }

        return ticket;
    }


    public String SHA1(String str) {
        try {
            MessageDigest digest = java.security.MessageDigest
                    .getInstance("SHA-1"); //如果是SHA加密只需要将"SHA-1"改成"SHA"即可
            digest.update(str.getBytes());
            byte messageDigest[] = digest.digest();
            // Create Hex String
            StringBuffer hexStr = new StringBuffer();
            // 字节数组转换为 十六进制 数
            for (int i = 0; i < messageDigest.length; i++) {
                String shaHex = Integer.toHexString(messageDigest[i] & 0xFF);
                if (shaHex.length() < 2) {
                    hexStr.append(0);
                }
                hexStr.append(shaHex);
            }
            return hexStr.toString();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }


    @Resource
    private WxMaProperties wxMaProperties;

    public String getSignature(String url) {

        String signature = "";

        String appid = wxMaProperties.getAppid();//微信公众号的appid
        String appsecret = wxMaProperties.getSecret();//微信公众号的appsecret

        //获取noncestr
        String noncestr = UUID.randomUUID().toString();

        String timestamp = Long.toString(System.currentTimeMillis() / 1000);
        //获取access_token
        String access_token = getAccessToken(appid, appsecret);
        //获取jspai_ticket
        String jsapi_ticket = getTicket(access_token);
        //将四个数据进行组合，传给SHA1进行加密
        String str = "jsapi_ticket=" + jsapi_ticket +
                "&noncestr=" + noncestr +
                "&timestamp=" + timestamp +
                "&url=" + url;

        //sha1加密
        signature = SHA1(str);

        return signature;
    }

    public Map getMapDataForH5(String url) {

        String signature = "";

        String appid = wxMaProperties.getAppid();//微信公众号的appid
        String appsecret = wxMaProperties.getSecret();//微信公众号的appsecret

        //获取noncestr
        String noncestr = UUID.randomUUID().toString();

        String timestamp = Long.toString(System.currentTimeMillis() / 1000);
        //获取access_token
        String access_token = getAccessToken(appid, appsecret);
        //获取jspai_ticket
        String jsapi_ticket = getTicket(access_token);
        //将四个数据进行组合，传给SHA1进行加密
        String str = "jsapi_ticket=" + jsapi_ticket +
                "&noncestr=" + noncestr +
                "&timestamp=" + timestamp +
                "&url=" + url;

        //sha1加密
        signature = SHA1(str);

        Map map = new HashMap();
        map.put("appid",appid);
        map.put("timestamp",timestamp);
        map.put("nonceStr",noncestr);
        map.put("signature",signature);
        return map;

    }


}