SpringBoot 实现微信扫码登录的示例代码

@RestController
@RequestMapping("/auth/wechat")
public class WechatAuthController {

    // 从配置文件读取（application.yml）
    @Value("${wechat.appid}")
    private String appId;

    @Value("${wechat.callback}")
    private String callbackUrl;

    /**
     * 生成微信登录二维码的URL
     */
    @GetMapping("/qrcode-url")
    public String getQrCodeUrl() {
        // 微信开放平台生成二维码的固定URL格式
        String url = "https://open.weixin.qq.com/connect/qrconnect" +
                "?appid=%s" +
                "&redirect_uri=%s" +
                "&response_type=code" +
                "&scope=snsapi_login" +  // 固定值
                "&state=YOUR_STATE";     // 防CSRF攻击随机字符串（需存储校验）

        return String.format(url, appId, URLEncoder.encode(callbackUrl, StandardCharsets.UTF_8));
    }
}

/**
 * 微信回调接口（需与开放平台配置的回调地址一致）
 */
@GetMapping("/callback")
public ResponseEntity<?> callback(@RequestParam String code, @RequestParam String state) {
    // 1. 校验state参数（防止CSRF攻击）
    if (!validateState(state)) {
        return ResponseEntity.badRequest().body("非法请求");
    }

    // 2. 用code换取access_token
    String tokenUrl = "https://api.weixin.qq.com/sns/oauth2/access_token" +
            "?appid=%s" +
            "&secret=%s" +
            "&code=%s" +
            "&grant_type=authorization_code";

    String response = OkHttpUtil.get(String.format(tokenUrl, appId, appSecret, code));
    JsonNode tokenJson = JsonUtil.parse(response);

    // 3. 获取用户信息
    String userInfoUrl = "https://api.weixin.qq.com/sns/userinfo" +
            "?access_token=%s" +
            "&openid=%s";

    String userResponse = OkHttpUtil.get(
            String.format(userInfoUrl, tokenJson.get("access_token").asText(),
                                   tokenJson.get("openid").asText()));
    JsonNode userInfo = JsonUtil.parse(userResponse);

    // 4. 处理用户登录（示例：创建本地用户或绑定已有账号）
    User user = userService.createOrUpdateWechatUser(userInfo);

    // 5. 生成JWT或Session（此处以JWT为例）
    String jwtToken = JwtUtil.generateToken(user.getId());

    return ResponseEntity.ok().header("Authorization", jwtToken).build();
}

public class OkHttpUtil {
    /**
     * 发送GET请求
     */
    public static String get(String url) throws IOException {
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder().url(url).build();
        try (Response response = client.newCall(request).execute()) {
            return response.body().string();
        }
    }
}

public class JsonUtil {
    private static final ObjectMapper mapper = new ObjectMapper();

    /**
     * JSON字符串转对象
     */
    public static JsonNode parse(String json) throws JsonProcessingException {
        return mapper.readTree(json);
    }
}

wechat:
  appid: wx1234567890abcdef  # 微信应用ID
  app-secret: your_app_secret_here  # 微信应用密钥
  callback: https://www.yourdomain.com/auth/wechat/callback  # 授权回调地址