CancelToken 介绍

​ axios中用于取消请求的方法

使用

• 可以使用 CancelToken.source 工厂方法创建 cancel token，像这样：

  const CancelToken = axios.CancelToken;
  const source = CancelToken.source();
  
  axios.get('/user/12345', {
    cancelToken: source.token
  }).catch(function(thrown) {
    if (axios.isCancel(thrown)) {
      console.log('Request canceled', thrown.message);
    } else {
       // 处理错误
    }
  });
  
  axios.post('/user/12345', {
    name: 'new name'
  }, {
    cancelToken: source.token
  })
  
  // 取消请求（message 参数是可选的）
  source.cancel('Operation canceled by the user.');
  

• 还可以通过传递一个 executor 函数到 CancelToken 的构造函数来创建 cancel token：

  const CancelToken = axios.CancelToken;
  let cancel;
  
  axios.get('/user/12345', {
    cancelToken: new CancelToken(function executor(c) {
      // executor 函数接收一个 cancel 函数作为参数
      cancel = c;
    })
  });
  
  // cancel the request
  cancel();
  

  注意: 可以使用同一个 cancel token 取消多个请求

例子：重复请求处理

​ 思路：新建一个数组存请求相关信息，在请求拦截中进行对当前请求进行处理，如果之前请求过则提示用户不要重复请求，直接中断当前请求，如果没请求过则将当前请求信息添加到数组中。在响应拦截中对于已经返回的请求做删除操作，确保可以在请求返回成功后再次请求。

import axios from 'axios'
import { message, Loading, Notification } from 'element-ui'

const instance = axios.create({
  'Content-Type': 'application/json;charset=UTF-8',
  'timeout': 20000
})

let loading = ''
let map = []

instance.interceptors.request.use(
  config => {
    if (config.isLoading) {
      // 开启loading
      loading = Loading.service({
        lock: true,
        text: '拼命加载中...',
        background: 'rgba(0, 0, 0, 0.7)'
      })
    } else {
      let cancel
      config.cancelToken = new axios.CancelToken(function (c) {
        cancel = c
      })
      let matchIndex = findMatchIndex (map, config)
      if (matchIndex !== -1) {
        Notification({
          title: '提示',
          message: '请不要重复提交',
          type: 'error'
        })
        cancel('请求中断')
      } else {
        map.push({
          url: config.url,
          method: config.method,
          params: config.params
        })
      }
    }
    return config
  },
  error => {
    return Promise.reject(error)
  }
)

instance.interceptors.response.use(
  response => {
    let { config } = response
    let matchIndex = findMatchIndex (map, config)
    console.log(matchIndex, 'matchIndex')
    if (matchIndex !== -1) {
      map.splice(matchIndex, 1)
    }
    if (config.isLoading) {
      loading.close()
    }
    return response.data
  },
  error => {
    console.log(error, 'error')
    if (error.message === '请求中断') {
      return Promise.reject(error)
    }
    loading.close()
    // 通用错误处理
    let normalErrorCodes = [400, 401, 404]
    if (normalErrorCodes.includes(error.response.status)) {
      message.error(error.response.data.msg || '请求错误')
    }
    return Promise.reject(error)
  }
)

export default {
  post (url, params = {}) {
    const { isLoading = true } = params
    return instance({
      method: 'post',
      url: url,
      data: params,
      timeout: 20000,
      isLoading
    })
  },

  get (url, params = {}) {
    const { isLoading = true } = params
    return instance({
      method: 'get',
      url: url,
      params,
      isLoading
    })
  },

  delete (url, params = {}) {
    let { isLoading = true } = params
    return instance({
      method: 'delete',
      url: url,
      params,
      isLoading
    })
  },

  put (url, params = {}) {
    let { isLoading = true } = params
    return instance({
      method: 'put',
      url: url,
      data: params,
      isLoading,
      timeout: 20000
    })
  }
}

function findMatchIndex (map, config) {
  return map.findIndex((item) => {
    return (item.url === config.url && item.method === config.method && diff(item.params, config.params))
  })
}

function diff(obj1, obj2) {
  if (Object.keys(obj1).length !== Object.keys(obj2).length) {
    return false
  }
  let obj1Keys = Object.keys(obj1)
  for (let i = 0; i < obj1Keys.length; i++) {
    if (obj1[obj1Keys[i]] !== obj2[obj1Keys[i]]) {
      return false
    }
  }
  return true
}

参考资料

axios中文文档

友情连接

axios源码分析——取消请求