微信扫码登录-java

步骤：

1.微信开放平台注册https://open.weixin.qq.com/

2.完善开发者信息

3.申请创建 网站应用 

4.填写对应信息 然后坐等审核通过

注意点：

申请创建网站应用 授权回调地址 必须是域名 不能用ip 不能带端口 

如果你的回调地址是 www.test.com/login/callBack 那这里就只用填写www.test.com 而在你代码里 需要填写具体的回调地址

---

后端开发：

流程：

1.获取微信二维码

2.用户扫码确认登录生成code和state，微信会根据回调地址，自己带上code和state

3.根据code换access_token，做本地操作

代码：

<!-这里用到的依赖-->
<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.8.11</version>
</dependency>

#微信appid应用唯一标识
wx.open.app_id=wx123456
#微信appSecret
wx.open.app_secret=3e8de831138d
#回调地址 这里是具体的回调地址
wx.open.redirect_url=http://www.test.com/wxLogin/callBack

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class ConstantPropertiesUtil implements InitializingBean {

    @Value("${wx.open.app_id}")
    private String appId;

    @Value("${wx.open.app_secret}")
    private String appSecret;

    @Value("${wx.open.redirect_url}")
    private String redirectUrl;

    public static String WX_OPEN_APP_ID;
    public static String WX_OPEN_APP_SECRET;
    public static String WX_OPEN_REDIRECT_URL;

    
    @Override
    public void afterPropertiesSet() throws Exception {
        WX_OPEN_APP_ID = appId;
        WX_OPEN_APP_SECRET = appSecret;
        WX_OPEN_REDIRECT_URL = redirectUrl;
    }
}

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiImplicitParam;
import io.swagger.annotations.ApiImplicitParams;
import io.swagger.annotations.ApiOperation;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;

@RestController
@RequestMapping("/wxLogin")
public class WeChatLogin {


    @ApiOperation(value = "获取微信二维码")
    @GetMapping("/getWxCode")
    public ApiResult getWxCode() {
         //微信开放平台授权baseUrl
        String baseUrl = "https://open.weixin.qq.com/connect/qrconnect" +
                "?appid=%s" +
                "&redirect_uri=%s" +
                "&response_type=code" +
                "&scope=snsapi_login" +
                "&state=%s" +
                "#wechat_redirect";
        String redirectUrl = ConstantPropertiesUtil.WX_OPEN_REDIRECT_URL;
        try {
            redirectUrl = URLEncoder.encode(redirectUrl, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
       
        String qrcodeUrl = String.format(
                baseUrl,
                ConstantPropertiesUtil.WX_OPEN_APP_ID,
                redirectUrl,
        //这里的onlineEdu 微信建议第三方带上这个参数 可随机为任何
                "onlineEdu");
        return ApiResult.successWithObject("redirect:" + qrcodeUrl);
    }


    @ApiOperation(value = "回调地址")
    @GetMapping ("/callBack")
    public ApiResult callBack(
            @RequestParam("code") String code,
            @RequestParam("state") String state,
            ) throws Exception{

   
        //获取access_token
        String url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=CODE&grant_type=authorization_code";
        url = url.replace("APPID", ConstantPropertiesUtil.WX_OPEN_APP_ID)
                .replace("SECRET", ConstantPropertiesUtil.WX_OPEN_APP_SECRET)
                .replace("CODE", code);
        String tokenInfoStr = HttpClientUtil.doGet(url);
        JSONObject tokenInfoObject = JSONUtil.parseObj(tokenInfoStr);

        //获取用户信息
        String userInfoUrl = "https://api.weixin.qq.com/sns/userinfo?access_token=ACCESS_TOKEN&openid=OPENID";
        userInfoUrl = userInfoUrl.replace("ACCESS_TOKEN", tokenInfoObject.getStr("access_token"))
                .replace("OPENID", tokenInfoObject.getStr("openid"));
        String userInfoStr = HttpClientUtil.doGet(userInfoUrl);

        JSONObject wxUserInfo = JSONUtil.parseObj(userInfoStr);

        //判断是否存该用户
        String openid = tokenInfoObject.getStr("openid");
        String unionId = tokenInfoObject.getStr("unionid");
        User userInfo = userService.getByOpenid(openid);
        if (userInfo == null){
            //业务上进行保存用户各信息
            
        }

        //存在直接进行登录 生成token或其他 根据自己需求来 
        String token = "token";
        return ApiResult.successWithObject(token);
    }
}