Axios 应用详解

一、前言

Axios 是基于 promise 的 HTTP 库，可以用在浏览器和 node.js 中。

二、功能特性

• 在浏览器中发送 XMLHttpRequests 请求；
• 在 node.js 中发送 http请求；
• 支持 Promise API；
• 拦截请求和响应；
• 转换请求和响应数据；
• 自动转换 JSON 数据；
• 客户端支持保护安全免受 XSRF 攻击；
• 浏览器支持；

三、安装

使用 bower:

$ bower install axios

使用 npm:

$ npm install axios

四、配置项与响应结构

4.1 配置项

可用的请求配置项如下，只有 url 是必需的。如果没有指定 method ，默认请求方法是 GET。

{
// `url` is the server URL that will be used for the request
url: '/user',

// `method` is the request method to be used when making the request
method: 'get', // default

// `baseURL` will be prepended to `url` unless `url` is absolute. 
// It can be convenient to set `baseURL` for an instance of axios to pass relative URLs 
// to methods of that instance.
baseURL: 'https://some-domain.com/api/',

// `transformRequest` allows changes to the request data before it is sent to the server
// This is only applicable for request methods 'PUT', 'POST', and 'PATCH'
// The last function in the array must return a string or an ArrayBuffer
transformRequest: [function (data) {
// Do whatever you want to transform the data

return data;
}],

// `transformResponse` allows changes to the response data to be made before
// it is passed to then/catch
transformResponse: [function (data) {
// Do whatever you want to transform the data

return data;
}],

// `headers` are custom headers to be sent
headers: {'X-Requested-With': 'XMLHttpRequest'},

// `params` are the URL parameters to be sent with the request
params: {
ID: 12345
},

// `paramsSerializer` is an optional function in charge of serializing `params`
// (e.g. https://www.npmjs.com/package/qs, http://api.jquery.com/jquery.param/)
paramsSerializer: function(params) {
return Qs.stringify(params, {arrayFormat: 'brackets'})
},

// `data` is the data to be sent as the request body
// Only applicable for request methods 'PUT', 'POST', and 'PATCH'
// When no `transformRequest` is set, must be a string, an ArrayBuffer or a hash
data: {
firstName: 'Fred'
},

// `timeout` specifies the number of milliseconds before the request times out.
// If the request takes longer than `timeout`, the request will be aborted.
timeout: 1000,

// `withCredentials` indicates whether or not cross-site Access-Control requests
// should be made using credentials
withCredentials: false, // default

// `adapter` allows custom handling of requests which makes testing easier.
// Call `resolve` or `reject` and supply a valid response (see [response docs](#response-api)).
adapter: function (resolve, reject, config) {
/* ... */
},

// `auth` indicates that HTTP Basic auth should be used, and supplies credentials.
// This will set an `Authorization` header, overwriting any existing
// `Authorization` custom headers you have set using `headers`.
auth: {
username: 'janedoe',
password: 's00pers3cret'
}

// `responseType` indicates the type of data that the server will respond with
// options are 'arraybuffer', 'blob', 'document', 'json', 'text'
responseType: 'json', // default

// `xsrfCookieName` is the name of the cookie to use as a value for xsrf token
xsrfCookieName: 'XSRF-TOKEN', // default

// `xsrfHeaderName` is the name of the http header that carries the xsrf token value
xsrfHeaderName: 'X-XSRF-TOKEN', // default

// `progress` allows handling of progress events for 'POST' and 'PUT uploads'
// as well as 'GET' downloads
progress: function(progressEvent) {
// Do whatever you want with the native progress event
}
}

4.2 响应的数据结构

响应的数据包括下面的信息：

{
// `data` is the response that was provided by the server
data: {},

// `status` is the HTTP status code from the server response
status: 200,

// `statusText` is the HTTP status message from the server response
statusText: 'OK',

// `headers` the headers that the server responded with
headers: {},

// `config` is the config that was provided to `axios` for the request
config: {}
}

当使用 then 或者 catch 时, 会收到下面的响应：

axios.get('/user/12345')
	.then(function(response) {
		console.log(response.data);
		console.log(response.status);
		console.log(response.statusText);
		console.log(response.headers);
		console.log(response.config);
});

五、示例

5.1 发送 GET 请求

// Make a request for a user with a given ID
axios.get('/user?ID=12345')
   .then(function (response) {
      console.log(response);
      })
   .catch(function (response) {
      console.log(response);
   });
// Optionally the request above could also be done as
axios.get('/user', {
   params: {
      ID: 12345
   }
   })
   .then(function (response) {
      console.log(response);
   })
   .catch(function (response) {
      console.log(response);
   });

5.2 发送 POST 请求

axios.post('/user', {
    firstName: 'Fred',
    lastName: 'Flintstone'
})
   .then(function (response) {
      console.log(response);
   })
   .catch(function (response) {
      console.log(response);
   });

5.3 发送多个并发请求

处理并发请求方法如下：

axios.all(iterable)
axios.spread(callback)

function getUserAccount() {
   return axios.get('/user/12345');
}
function getUserPermissions() {
   return axios.get('/user/12345/permissions');
}
axios.all([getUserAccount(), getUserPermissions()])
   .then(axios.spread(function (acct, perms) {
      // Both requests are now complete
   }));

可以通过给 axios传递对应的参数来定制请求：

axios(config)
// Send a POST request
axios({
   method: 'post',
   url: '/user/12345',
   data: {
      firstName: 'Fred',
      lastName: 'Flintstone'
   }
});
axios(url[, config])
// Sned a GET request (default method)
axios('/user/12345');

六、请求方法别名

为方便起见，axios为所有支持的请求方法都提供了别名。

axios.get(url[, config])
axios.delete(url[, config])
axios.head(url[, config])
axios.post(url[, data[, config]])
axios.put(url[, data[, config]])
axios.patch(url[, data[, config]])

注意： 当使用别名方法时， url、 method 和 data 属性不需要在 config 参数里面指定。

七、默认配置

可以为每一个请求指定默认配置。

7.1 全局 axios 默认配置

axios.defaults.baseURL = 'https://api.example.com';
axios.defaults.headers.common['Authorization'] = AUTH_TOKEN;
axios.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded';

7.2 自定义实例默认配置

// Set config defaults when creating the instance
var instance = axios.create({
	baseURL: 'https://api.example.com'
});
// Alter defaults after instance has been created
instance.defaults.headers.common['Authorization'] = AUTH_TOKEN;

7.3 配置的优先顺序

Config will be merged with an order of precedence. The order is library defaults found in lib/defaults.js, then defaults property of the instance, and finally config argument for the request. The latter will take precedence over the former. Here’s an example.

// Create an instance using the config defaults provided by the library
// At this point the timeout config value is `0` as is the default for the library
var instance = axios.create();

// Override timeout default for the library
// Now all requests will wait 2.5 seconds before timing out
instance.defaults.timeout = 2500;

// Override timeout for this request as it's known to take a long time
instance.get('/longRequest', {
timeout: 5000
}); 

八、拦截器

8.1 添加拦截器

可以在处理 then 或 catch 之前拦截请求和响应。

// 添加一个请求拦截器
axios.interceptors.request.use(function (config) {
   // Do something before request is sent
   return config;
}, function (error) {
   // Do something with request error
   return Promise.reject(error);
});

// 添加一个响应拦截器
axios.interceptors.response.use(function (response) {
   // Do something with response data
   return response;
}, function (error) {
   // Do something with response error
   return Promise.reject(error);
});

8.2 移除一个拦截器

var myInterceptor = axios.interceptors.request.use(function () {/*...*/});
axios.interceptors.request.eject(myInterceptor);

也可以给自定义的 axios 实例添加拦截器：

var instance = axios.create();
instance.interceptors.request.use(function () {/*...*/});

错误处理

axios.get('/user/12345')
   .catch(function (response) {
      if (response instanceof Error) {
         // Something happened in setting up the request that triggered an Error
         console.log('Error', response.message);
		} else {
		// The request was made, but the server responded with a status code
		// that falls out of the range of 2xx
		   console.log(response.data);
		   console.log(response.status);
		   console.log(response.headers);
		   console.log(response.config);
		}
});

九、Promises

axios 依赖原生 ES6 Promise 实现，如果浏览器环境不支持 ES6 Promises，需要引入 polyfill。

9.1 TypeScript

axios 包含一个 TypeScript 定义。

/// <reference path="axios.d.ts" />
import * as axios from 'axios';
axios.get('/user?ID=12345');

Credits

axios is heavily inspired by the $http service provided in Angular.
Ultimately axios is an effort to provide a standalone $http-like service for use outside of Angular.