1. java 二维码生成工具类

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import com.pdatao.api.controller.file.FileController;
import com.pdatao.api.error.CommunityException;
import org.apache.commons.io.IOUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.springframework.web.multipart.MultipartFile;import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;@Component
public class MpQrCodeUtil {@ResourceFileController fileController;@Value("${mp.wechat.appid}")private String mpAppId;@Value("${mp.wechat.secret}")private String mpSecretId;@Value("${qrcode.pageHome}")private String pageHome;@Value("${spring.profiles.active:}")private String activeProfile;private static final String API_GET_TOKEN = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=%s&secret=%s";private static final String API_GET_QR_CODE = "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token=%s";private static String cachedToken = null;private static long tokenExpireTime = 0;public String getMpQRCode(Long orderId, HttpServletRequest request) throws Exception {String scenes = "id=" + orderId + "&v=1";String envVersion = "";if ("prod-plus".equals(activeProfile)) {envVersion = "release";}return this.getQRCodeWeb(scenes,envVersion,orderId,request);}public String getQRCodeWeb(String scenes, String envVersion, Long orderId, HttpServletRequest request) throws Exception {String accessToken = getToken(mpAppId, mpSecretId);return getQRCode(accessToken, scenes, envVersion, orderId, request);}public static String getToken(String appId, String appSecret) throws Exception {// 1. 检查缓存是否有效if (cachedToken != null && System.currentTimeMillis() < tokenExpireTime) {return cachedToken;}HttpURLConnection conn = null;try {String url = String.format(API_GET_TOKEN, appId, appSecret);conn = (HttpURLConnection) new URL(url).openConnection();conn.setConnectTimeout(5000);conn.setReadTimeout(5000);conn.setRequestMethod("GET");int statusCode = conn.getResponseCode();if (statusCode != 200) {// 读取错误流String errorJson = IOUtils.toString(conn.getErrorStream(), StandardCharsets.UTF_8);throw new CommunityException("微信接口错误: " + errorJson);}JSONObject result = new JSONObject(IOUtils.toString(conn.getInputStream(), StandardCharsets.UTF_8));cachedToken = result.getStr("access_token");long expiresIn = result.getLong("expires_in") * 1000; // 转为毫秒tokenExpireTime = System.currentTimeMillis() + expiresIn - 600_000;return cachedToken;} finally {if (conn != null) conn.disconnect();}}public String getQRCode(String accessToken, String scenes, String envVersion, Long orderId, HttpServletRequest request) throws Exception {HttpURLConnection httpURLConnection = null;try {URL url = new URL(String.format(API_GET_QR_CODE, accessToken));httpURLConnection = (HttpURLConnection) url.openConnection();httpURLConnection.setRequestMethod("POST");// 提交模式// 发送POST请求必须设置如下两行httpURLConnection.setDoOutput(true);httpURLConnection.setDoInput(true);// 发送请求参数com.alibaba.fastjson.JSONObject paramJson = new com.alibaba.fastjson.JSONObject();paramJson.put("scene", scenes);paramJson.put("page", pageHome);paramJson.put("env_version", StrUtil.isNotEmpty(envVersion) ? envVersion : "trial");paramJson.put("check_path", false);try (PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream())) {printWriter.write(paramJson.toString());printWriter.flush();}// 检查响应码int responseCode = httpURLConnection.getResponseCode();if (responseCode != HttpURLConnection.HTTP_OK) {cachedToken = null;throw new CommunityException("生成二维码失败：HTTP错误码 " + responseCode);}// 检查内容类型String contentType = httpURLConnection.getContentType();if (contentType == null || !contentType.startsWith("image/")) {cachedToken = null;throw new CommunityException("生成二维码失败：接口返回非图片数据（" +  (contentType != null ? contentType : "未知内容类型") + "）");}try (InputStream is = httpURLConnection.getInputStream(); ByteArrayOutputStream baos = new ByteArrayOutputStream();) {byte[] buffer = new byte[1024];int len = -1;while ((len = is.read(buffer)) != -1) {baos.write(buffer, 0, len);}byte[] imageData = baos.toByteArray();// 简单验证是否是有效图片（可选）if (imageData.length == 0) {cachedToken = null;throw new CommunityException("生成二维码失败：返回空图片数据");}MultipartFile multipartFile = new ByteArrayMultipartFile(orderId + "_mpqrcode",          // 表单字段名orderId + "_mpqrcode.png",      // 文件名"image/png",                  // 内容类型imageData                  // 内容);com.alibaba.fastjson.JSONObject json = fileController.upload(multipartFile,request);if (json == null || !json.containsKey("url")) {throw new CommunityException("上传图片失败：响应数据异常");}return json.getString("url");}} catch (Exception e) {e.printStackTrace();throw new CommunityException("生成二维码失败："+e.getMessage());} finally {if (httpURLConnection != null) {httpURLConnection.disconnect();}}}}

2. 部分可自行调整的代码解释

FileController： 我自己的上传图片到服务器的类

mpAppId：  小程序appid

mpSecretId： 小程序 SecretId

pageHome： 要跳转的小程序的页面地址（例如： ‘pages/userInfo/userInfoHome’）

activeProfile： 我自己的判断当前运行环境的配置（可以忽略）

@Resource
FileController fileController;@Value("${mp.wechat.appid}")
private String mpAppId;
@Value("${mp.wechat.secret}")
private String mpSecretId;@Value("${qrcode.pageHome}")
private String pageHome;
@Value("${spring.profiles.active:}")
private String activeProfile;

getMpQRCode 外部调用的方法，自定义自己需要传入什么值

Long orderId ： 这个是我为了生成二维码路径时携带的参数

HttpServletRequest request： 这个参数，和二维码生成逻辑没有任何关系，我这里使用只是因为上传图片的地方需要这个值，这个比较冗余

scenes： 定义页面地址携带什么参数

if ("prod-plus".equals(activeProfile)) {envVersion = "release";
}      这个是为了判断生成什么环境的二维码图片（正式版/ 体验版） 

public String getMpQRCode(Long orderId, HttpServletRequest request) throws Exception {String scenes = "id=" + orderId + "&v=1";String envVersion = "";if ("prod-plus".equals(activeProfile)) {envVersion = "release";}return this.getQRCodeWeb(scenes,envVersion,orderId,request);
}

imageData ： 这个就是生成的二维码图片信息

下面的其他信息，都是为了把这个图片的信息，上传到自己项目中保存，最终返回图片地址

byte[] imageData = baos.toByteArray();// 简单验证是否是有效图片（可选）
if (imageData.length == 0) {throw new CommunityException("生成核销二维码失败：返回空图片数据");
}MultipartFile multipartFile = new ByteArrayMultipartFile(orderId + "_mpqrcode",          // 表单字段名orderId + "_mpqrcode.png",      // 文件名"image/png",                  // 内容类型imageData                  // 内容
);
com.alibaba.fastjson.JSONObject json = fileController.upload(multipartFile,request);
if (json == null || !json.containsKey("url")) {throw new CommunityException("上传二维码失败：响应数据异常");
}
return json.getString("url");

3.小程序中获取携带的参数

以我上述的参数为例：（微信小程序使用的 uniapp）

onLoad(option) {if (option.scene) {const scene = decodeURIComponent(option.scene);const params = this.parseSceneParams(scene);console.log(params.id)console.log(params.v)}},methods: {parseSceneParams(scene) {const params = {};if (!scene) return params;const pairs = scene.split('&');pairs.forEach(pair => {const [key, value] = pair.split('=');if (key) params[key] = value;});return params;},
}