response源码分析

依赖模块

  1. const contentDisposition = require('content-disposition')
  2. // 创建和解析 HTTP 头 Content-Disposition
  4. const getType = require('cache-content-type')
  5. // 创建 Content-Type 值并缓存
  7. const onFinish = require('on-finished')
  8. // 当 HTTP 请求终止时执行回调
  10. const escape = require('escape-html')
  11. // 转义 HTML 中特殊符号为实体编码
  13. const typeis = require('type-is').is
  14. // 类型检查
  16. const statuses = require('statuses')
  17. // 提供状态码与消息的一一对应关系
  19. const destroy = require('destroy')
  20. // 释放流
  22. const assert = require('assert')
  23. // 提供了一组验证不变量的断言函数
  25. const extname = require('path').extname
  26. // 获取文件拓展名
  28. const vary = require('vary')
  29. // 操作 HTTP 头
  31. const only = require('only')
  32. // 设置对象白名单属性
  34. const util = require('util')
  35. // 工具模块，支持 Node.js 内部 API 的需求
  37. const encodeUrl = require('encodeurl')
  38. // 百分号编码 url
  40. const Stream = require('stream')
  41. // 提供了用于实现流接口的 API

导出对象

  1. module.exports = {
  2.     // 内容如下
  3. }

socket

  1. get socket () {
  2.     return this.res.socket
  3. }

header

  1. get header () {
  2.     const { res } = this
  3.     return typeof res.getHeaders === 'function'
  4.         ? res.getHeaders()
  5.     : res._headers || {} // Node < 7.7
  6. }
  8. get headers () {
  9.     return this.header
  10. }

status

  1. get status () {
  2.     return this.res.statusCode
  3. }
  5. set status (code) {
  6.     if (this.headerSent) return
  8.     assert(Number.isInteger(code), 'status code must be a number')
  9.     assert(code >= 100 && code <= 999, `invalid status code: ${code}`)
  10.     this._explicitStatus = true
  11.     this.res.statusCode = code
  12.     if (this.req.httpVersionMajor < 2) this.res.statusMessage = statuses[code]
  13.     if (this.body && statuses.empty[code]) this.body = null
  14. }

message

  1. get message () {
  2.     return this.res.statusMessage || statuses[this.status]
  3. }
  5. set message (msg) {
  6.     this.res.statusMessage = msg
  7. }

body

  1. get body () {
  2.     return this._body
  3. }
  5. set body (val) {
  6.     const original = this._body
  7.     this._body = val
  9.     if (val == null) {
  10.         if (!statuses.empty[this.status]) {
  11.             if (this.type === 'application/json') {
  12.                 this._body = 'null'
  13.                 return
  14.             }
  15.             this.status = 204
  16.         }
  17.         if (val === null) this._explicitNullBody = true
  18.         this.remove('Content-Type')
  19.         this.remove('Content-Length')
  20.         this.remove('Transfer-Encoding')
  21.         return
  22.     }
  24.     if (!this._explicitStatus) this.status = 200
  26.     const setType = !this.has('Content-Type')
  28.     if (typeof val === 'string') {
  29.         if (setType) this.type = /^\s*</.test(val) ? 'html' : 'text'
  30.         this.length = Buffer.byteLength(val)
  31.         return
  32.     }
  34.     if (Buffer.isBuffer(val)) {
  35.         if (setType) this.type = 'bin'
  36.         this.length = val.length
  37.         return
  38.     }
  40.     if (val instanceof Stream) {
  41.         onFinish(this.res, destroy.bind(null, val))
  42.         if (original !== val) {
  43.             val.once('error', err => this.ctx.onerror(err))
  44.             // overwriting
  45.             if (original != null) this.remove('Content-Length')
  46.         }
  48.         if (setType) this.type = 'bin'
  49.         return
  50.     }
  52.     this.remove('Content-Length')
  53.     this.type = 'json'
  54. }

length

  1. set length (n) {
  2.     if (!this.has('Transfer-Encoding')) {
  3.         this.set('Content-Length', n)
  4.     }
  5. }
  7. get length () {
  8.     if (this.has('Content-Length')) {
  9.         return parseInt(this.get('Content-Length'), 10) || 0
  10.     }
  12.     const { body } = this
  13.     if (!body || body instanceof Stream) return undefined
  14.     if (typeof body === 'string') return Buffer.byteLength(body)
  15.     if (Buffer.isBuffer(body)) return body.length
  16.     return Buffer.byteLength(JSON.stringify(body))
  17. }

headerSent

  1. get headerSent () {
  2.     return this.res.headersSent
  3. }

type

  1. set type (type) {
  2.     type = getType(type)
  3.     if (type) {
  4.         this.set('Content-Type', type)
  5.     } else {
  6.         this.remove('Content-Type')
  7.     }
  8. }
  10. get type () {
  11.     const type = this.get('Content-Type')
  12.     if (!type) return ''
  13.     return type.split(';', 1)[0]
  14. }

lastModified

  1. set lastModified (val) {
  2.     if (typeof val === 'string') val = new Date(val)
  3.     this.set('Last-Modified', val.toUTCString())
  4. }
  6. get lastModified () {
  7.     const date = this.get('last-modified')
  8.     if (date) return new Date(date)
  9. }

etag

  1. set etag (val) {
  2.     if (!/^(W\/)?"/.test(val)) val = `"${val}"`
  3.     this.set('ETag', val)
  4. }
  6. get etag () {
  7.     return this.get('ETag')
  8. }

writable

  1. get writable () {
  2.     if (this.res.writableEnded || this.res.finished) return false
  4.     const socket = this.res.socket
  6.     if (!socket) return true
  7.     return socket.writable
  8. }

vary 设置响应头

  1. vary (field) {
  2.     if (this.headerSent) return
  4.     vary(this.res, field)
  5. }

redirect 重定向

  1. redirect (url, alt) {
  2.     if (url === 'back') url = this.ctx.get('Referrer') || alt || '/'
  3.     this.set('Location', encodeUrl(url))
  5.     if (!statuses.redirect[this.status]) this.status = 302
  7.     if (this.ctx.accepts('html')) {
  8.         url = escape(url)
  9.         this.type = 'text/html; charset=utf-8'
  10.         this.body = `Redirecting to <a href="${url}">${url}</a>.`
  11.         return
  12.     }
  14.     this.type = 'text/plain; charset=utf-8'
  15.     this.body = `Redirecting to ${url}.`
  16. }

attachment 设置响应头 Content-Disposition

  1. attachment (filename, options) {
  2.     if (filename) this.type = extname(filename)
  3.     this.set('Content-Disposition', contentDisposition(filename, options))
  4. }

is 类型判断

  1. is (type, ...types) {
  2.     return typeis(this.type, type, ...types)
  3. }

get 获取响应头

  1.   get (field) {
  2.     return this.res.getHeader(field)
  3.   }

has 判断是否存在响应头

  1. has (field) {
  2.     return typeof this.res.hasHeader === 'function'
  3.         ? this.res.hasHeader(field)
  4.     // Node < 7.7
  5.     : field.toLowerCase() in this.headers
  6. }

set 设置响应头

  1. set (field, val) {
  2.     if (this.headerSent) return
  4.     if (arguments.length === 2) {
  5.         if (Array.isArray(val)) val = val.map(v => typeof v === 'string' ? v : String(v))
  6.         else if (typeof val !== 'string') val = String(val)
  7.         this.res.setHeader(field, val)
  8.     } else {
  9.         for (const key in field) {
  10.             this.set(key, field[key])
  11.         }
  12.     }
  13. }

append 附加响应头字段

  1. append (field, val) {
  2.     const prev = this.get(field)
  4.     if (prev) {
  5.         val = Array.isArray(prev)
  6.             ? prev.concat(val)
  7.         : [prev].concat(val)
  8.     }
  10.     return this.set(field, val)
  11. }

remove 移除响应头

  1. remove (field) {
  2.     if (this.headerSent) return
  4.     this.res.removeHeader(field)
  5. }

inspect 检查函数

  1. inspect () {
  2.     if (!this.res) return
  3.     const o = this.toJSON()
  4.     o.body = this.body
  5.     return o
  6. }

toJSON 格式化函数

  1. toJSON () {
  2.     return only(this, [
  3.         'status',
  4.         'message',
  5.         'header'
  6.     ])
  7. }

flushHeaders 刷新响应头

  1. flushHeaders () {
  2.     this.res.flushHeaders()
  3. }

自定义检查函数

  1. if (util.inspect.custom) {
  2.     module.exports[util.inspect.custom] = module.exports.inspect
  3. }