java 生成微信小程序二维码 base64 格式并携带参数 java 后端 完整代码

以下是Java生成微信小程序带参数二维码的完整代码：

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.codec.binary.Base64;
import org.json.JSONObject;

public class WxMaQrcodeUtils {
    private static final String API_URL = "https://api.weixin.qq.com/cgi-bin/wxaapp/createwxaqrcode";
    private static final String PARAM_PAGE = "page";
    private static final String PARAM_SCENE = "scene";
    private static final String ACCESS_TOKEN_URL = "https://api.weixin.qq.com/cgi-bin/token";

    /**
     * 获取access_token
     *
     * @param appid 小程序appid
     * @param secret 小程序secret
     * @return access_token
     */
    public static String getAccessToken(String appid, String secret) {
        String accessToken = null;

        try {
            String url = ACCESS_TOKEN_URL + "?grant_type=client_credential&appid=" + appid + "&secret=" + secret;
            URL obj = new URL(url);
            HttpURLConnection con = (HttpURLConnection) obj.openConnection();
            con.setRequestMethod("GET");

            int responseCode = con.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream inputStream = con.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                StringBuilder stringBuilder = new StringBuilder();
                String line;
                while ((line = bufferedReader.readLine()) != null) {
                    stringBuilder.append(line);
                }
                bufferedReader.close();

                JSONObject jsonObject = new JSONObject(stringBuilder.toString());
                accessToken = jsonObject.getString("access_token");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return accessToken;
    }

    /**
     * 生成小程序带参数二维码
     *
     * @param accessToken 小程序access_token
     * @param page 小程序页面路径
     * @param scene 小程序页面参数
     * @return base64格式的二维码图片数据
     */
    public static String createQrcode(String accessToken, String page, String scene) {
        String base64Image = null;

        try {
            Map<String, Object> params = new HashMap<>();
            params.put(PARAM_PAGE, page);
            params.put(PARAM_SCENE, scene);

            URL obj = new URL(API_URL + "?access_token=" + accessToken);
            HttpURLConnection con = (HttpURLConnection) obj.openConnection();
            con.setRequestMethod("POST");
            con.setRequestProperty("Content-Type", "application/json");

            con.setDoOutput(true);
            con.getOutputStream().write(new JSONObject(params).toString().getBytes("UTF-8"));

            int responseCode = con.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream inputStream = con.getInputStream();
                byte[] imageBytes = new byte[inputStream.available()];
                inputStream.read(imageBytes);
                inputStream.close();

                base64Image = Base64.encodeBase64String(imageBytes);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return base64Image;
    }

    public static void main(String[] args) {
        String appid = "your_appid";
        String secret = "your_secret";
        String accessToken = getAccessToken(appid, secret);

        String page = "pages/index/index";
        String scene = "key=value";

        String base64Image = createQrcode(accessToken, page, URLEncoder.encode(scene));

        System.out.println(base64Image);
    }
}

注意，需要引入Apache Commons Codec库。

其中，getAccessToken方法用于获取小程序的access_token，createQrcode方法用于生成小程序带参数二维码并返回base64格式的图片数据。在main方法中调用以上两个方法即可生成小程序二维码。