java 微信小程序注册和登录 (精简demo)

1. 前端通过 wx.login 接口获得临时登录凭证 code, 传给后台

前端wx.login (API)

https://developers.weixin.qq.com/miniprogram/dev/api/open-api/login/wx.login.html

2. 后台调用jscode2session接口, 使用 code 换取 openid、unionid、session_key 等信息

小程序登录 (服务端)

https://developers.weixin.qq.com/miniprogram/dev/OpenApiDoc/user-login/code2Session.html

3. 注册和登录实现代码

import com.alibaba.fastjson.JSONObject;
import com.ruoyi.common.core.domain.AjaxResult;
import com.ruoyi.common.utils.StringUtils;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class LoginController {


    /**
     * 微信小程序注册和登录
     *
     * @param code  用户登录凭证（有效期五分钟）
     * @return
     */
    @RequestMapping("/login")
    public Object login(String code){

        if (StringUtils.isEmpty(code)) {
            return AjaxResult.error("登录凭证不能为空");
        }

        try {
            String appid = "AppID(小程序ID)";
            String secret = "AppSecret(小程序密钥)";
            String grant_type = "authorization_code";

            CloseableHttpClient httpClient = HttpClients.createDefault();
            // 小程序登录
            String url = "https://api.weixin.qq.com/sns/jscode2session?appid="+appid+"&secret="+secret+"&js_code="+code+"&grant_type="+grant_type;
            HttpGet get = new HttpGet(url);
            CloseableHttpResponse response = httpClient.execute(get);
            String result = EntityUtils.toString(response.getEntity(), "utf-8");
            JSONObject json = JSONObject.parseObject(result);
            if (!json.containsKey("errcode")) {
                String openid = json.getString("openid");
                String unionid = json.getString("unionid");

                // TODO 存数据库

                return "success";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "error";
    }
}