HTTP客户端是很多时候我们都需要用到的功能,今天就来介绍一个比较流行的JavaScript编写的HTTP客户端库axios。
如果你会使用npm的话,可以使用npm来装,非常方便。
$ npm install axios
如果你准备在浏览器中尝试使用,可以直接使用CDN。
<script src="https://unpkg.com/axios/dist/axios.min.js"></script>
在使用axios之前,先来介绍一下ES6标准中引入的Promise对象,它是为了方便异步编程而设立的。如果希望详细了解Promise对象的用法,可以查看这里。Promise对象含有then
和catch
方法,分别用来处理异步操作和抛出异常操作。所以如果一个方法返回Promise对象,我们就可以简单的像这样编写异步操作。
funtionReturnPromise(XXX)
.then(function (returnValue) {
//异步操作
})
.catch(function (error) {
//异常处理
})
HTTPBIN这个网站可以帮助我们测试HTTP请求, 所以这里使用它作为目标网站。
axios.get('http://httpbin.org/get?fuck=shit')
.then(function (response) {
console.log(response.data)
})
.catch(function (error) {
console.log(error)
})
当然请求参数也可以单独传进去。
axios.get('http://httpbin.org/get', {
params: {
fuck: "shit"
}
})
.then(function (response) {
console.log(response.data)
})
.catch(function (error) {
console.log(error)
})
POST请求的参数只能以参数的形式传入。
axios.post('http://httpbin.org/post', {
fuck: 'shit',
son: 'bitch'
})
.then(function (response) {
console.log(response.data)
})
.catch(function (error) {
console.log(error)
})
除了前面显式使用对应方法来发起请求,我们还可以使用配置来设置如何发送请求。例如,要发送一个POST请求,可以这么写。
axios({
method: 'post',
url: '/user/12345',
data: {
firstName: 'Fred',
lastName: 'Flintstone'
}
});
axios可以发送不同类型的HTTP请求,这些请求方法可以参考下面。
axios.request(config)
axios.get(url[, config])
axios.delete(url[, config])
axios.head(url[, config])
axios.options(url[, config])
axios.post(url[, data[, config]])
axios.put(url[, data[, config]])
axios.patch(url[, data[, config]])
有时候需要多次发起同一类型的请求,这时候可以创建请求实例。创建实例使用axios.create([config])
方法。下面创建了一个实例,然后用该实例发起请求。
let instance = axios.create({
baseURL: 'https://httpbin.org/',
timeout: 4000
})
instance.get('ip')
.then(function (response) {
console.log(response.data)
})
.catch(function (error) {
console.log(error)
})
实例上还有其他方法,基本和axios全局对象上的方法类似。
前面很多地方已经使用了配置对象。下面来详细介绍一下该对象。
{
// 请求地址
url: '/user',
// 请求方法类型
method: 'get', // default
// 基地址会和URL组合在一起,除非URL是绝对地址
// 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/',
// 该方法可以按照自己的需求将响应转换成需要的格式
// This is only applicable for request methods 'PUT', 'POST', and 'PATCH'
// The last function in the array must return a string or an instance of Buffer, ArrayBuffer,
// FormData or Stream
// You may modify the headers object.
transformRequest: [function (data, headers) {
// 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;
}],
// http头
headers: {'X-Requested-With': 'XMLHttpRequest'},
// 请求参数,会添加到URL上
// Must be a plain object or a URLSearchParams object
params: {
ID: 12345
},
// `paramsSerializer` 可以按照需要序列化参数
// (e.g. https://www.npmjs.com/package/qs, http://api.jquery.com/jquery.param/)
paramsSerializer: function(params) {
return Qs.stringify(params, {arrayFormat: 'brackets'})
},
// `data` 参数会以请求体的形式进行发送
// Only applicable for request methods 'PUT', 'POST', and 'PATCH'
// When no `transformRequest` is set, must be of one of the following types:
// - string, plain object, ArrayBuffer, ArrayBufferView, URLSearchParams
// - Browser only: FormData, File, Blob
// - Node only: Stream, Buffer
data: {
firstName: 'Fred'
},
// `timeout` 指定超时毫秒数
// 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.
// Return a promise and supply a valid response (see lib/adapters/README.md).
adapter: function (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', 'stream'
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
// `onUploadProgress` allows handling of progress events for uploads
onUploadProgress: function (progressEvent) {
// Do whatever you want with the native progress event
},
// `onDownloadProgress` allows handling of progress events for downloads
onDownloadProgress: function (progressEvent) {
// Do whatever you want with the native progress event
},
// `maxContentLength` defines the max size of the http response content allowed
maxContentLength: 2000,
// `validateStatus` defines whether to resolve or reject the promise for a given
// HTTP response status code. If `validateStatus` returns `true` (or is set to `null`
// or `undefined`), the promise will be resolved; otherwise, the promise will be
// rejected.
validateStatus: function (status) {
return status >= 200 && status < 300; // default
},
// `maxRedirects` defines the maximum number of redirects to follow in node.js.
// If set to 0, no redirects will be followed.
maxRedirects: 5, // default
// `httpAgent` and `httpsAgent` define a custom agent to be used when performing http
// and https requests, respectively, in node.js. This allows options to be added like
// `keepAlive` that are not enabled by default.
httpAgent: new http.Agent({ keepAlive: true }),
httpsAgent: new https.Agent({ keepAlive: true }),
// 'proxy' 指定请求使用的网络代理
// Use `false` to disable proxies, ignoring environment variables.
// `auth` indicates that HTTP Basic auth should be used to connect to the proxy, and
// supplies credentials.
// This will set an `Proxy-Authorization` header, overwriting any existing
// `Proxy-Authorization` custom headers you have set using `headers`.
proxy: {
host: '127.0.0.1',
port: 9000,
auth: {
username: 'mikeymike',
password: 'rapunz3l'
}
},
// `cancelToken` 指定取消token,这个token可以用来取消请求
// (see Cancellation section below for details)
cancelToken: new CancelToken(function (cancel) {
})
}
然后来介绍一下响应对象,也就是前面那些方法返回的response。
{
// `data` 请求返回的数据(HTML、JSON等)
data: {},
// `status` 状态码
status: 200,
// `statusText` 状态文本
statusText: 'OK',
// `headers` 响应头
// All header names are lower cased
headers: {},
// `config` axios请求使用的配置
config: {},
// `request` 产生这个响应的请求对象
// It is the last ClientRequest instance in node.js (in redirects)
// and an XMLHttpRequest instance the browser
request: {}
}
如果一个HTTP请求时间过长,可以取笑它。取消的使用方法如下。
let cancelToken = axios.CancelToken
let source = cancelToken.source()
axios.get('https://httpbin.org/ip', {
cancelToken: source.token
})
.then(function (response) {
console.log(response.data)
})
.catch(function (error) {
console.log(error)
})
source.cancel('取消了HTTP请求')
默认情况下,axios会将JavaScript对象序列化为JSON对象,如果需要用application/x-www-form-urlencoded
形式传送数据,可以使用下面的方法。
如果在浏览器中,可以使用URLSearchParams
对象。
var params = new URLSearchParams();
params.append('param1', 'value1');
params.append('param2', 'value2');
axios.post('/foo', params);
如果在Node环境下,可以使用qs
库。
var qs = require('qs');
axios.post('/foo', qs.stringify({ 'bar': 123 }));
最后,照例用一个小例子结束。这是一个HTML文件,将它保存,然后在浏览器中打开即可。为了简单起见,这里使用原生的JavaScript操作,用到的第三方库只有axios一个。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>主页</title>
</head>
<body>
<h1>IP地址查询</h1>
<button onclick="onClick()">点击查询IP地址</button>
<h2 id="ip"></h2>
<script src="https://unpkg.com/axios/dist/axios.min.js"></script>
<script>
function onClick() {
axios.get('https://httpbin.org/ip')
.then(function (response) {
let ip = document.getElementById('ip')
ip.textContent = response.data.origin
})
.catch(function (error) {
alert(error)
})
}
</script>
</body>
</html>