在微信小程序中写一个调用百度API拍照识别图片物品的

示例代码：

1. 在小程序页面中引入百度AI的SDK，并初始化：

const baiduAI = require('../../utils/baiduAI.js');
const baiduClient = new baiduAI.BaiduClient('YourAppId', 'YourAPIKey', 'YourSecretKey');

2. 在页面中添加一个拍照按钮：

<button bindtap="takePhoto">拍照识别</button>

3. 定义一个takePhoto方法，用于调用摄像头并发送识别请求：

takePhoto: function() {
  wx.chooseImage({
    count: 1,
    sizeType: ['original', 'compressed'],
    sourceType: ['camera'],
    success: (res) => {
      const tempFilePath = res.tempFilePaths[0];
      const param = {
        image: baiduAI.base64Encode(tempFilePath),
        baike_num: 5
      };
      baiduClient.getObject(param).then(result => {
        console.log(result);
        // 处理识别结果
      }).catch(error => {
        console.error(error);
      });
    },
    fail: (res) => {
      console.error(res);
    }
  })
}

4. 定义一个baiduAI.js文件，用于封装百度AI的API调用：

const BaiduClient = function(appId, apiKey, secretKey) {
  this.appId = appId;
  this.apiKey = apiKey;
  this.secretKey = secretKey;
  this.authToken = '';
};

BaiduClient.prototype.getAuthToken = function() {
  return new Promise((resolve, reject) => {
    wx.request({
      url: 'https://aip.baidubce.com/oauth/2.0/token',
      data: {
        grant_type: 'client_credentials',
        client_id: this.apiKey,
        client_secret: this.secretKey
      },
      success: (res) => {
        if (res.statusCode === 200) {
          this.authToken = res.data.access_token;
          resolve(res.data.access_token);
        } else {
          reject(`获取access_token失败，错误码：${res.statusCode}`);
        }
      },
      fail: (res) => {
        reject(`获取access_token失败，${res.errMsg}`);
      }
    })
  })
};

BaiduClient.prototype.getObject = function(param) {
  if (!this.authToken) {
    return this.getAuthToken().then(() => {
      return this.getObject(param);
    });
  }
  return new Promise((resolve, reject) => {
    wx.request({
      url: `https://aip.baidubce.com/rest/2.0/image-classify/v2/advanced_general?access_token=${this.authToken}`,
      method: 'POST',
      data: param,
      header: {
        'Content-Type': 'application/x-www-form-urlencoded'
      },
      success: (res) => {
        if (res.statusCode === 200) {
          resolve(res.data);
        } else {
          reject(`识别失败，错误码：${res.statusCode}`);
        }
      },
      fail: (res) => {
        reject(`识别失败，${res.errMsg}`);
      }
    })
  })
};

const base64Encode = function(file) {
  const bitmap = wx.getFileSystemManager().readFileSync(file);
  return wx.arrayBufferToBase64(bitmap);
};

module.exports = {
  BaiduClient,
  base64Encode
};

注意：需要在百度AI平台上申请access_token，并填写到代码中的getAuthToken方法中。另外，还需要在小程序的app.json文件中添加百度AI的域名白名单。