最近接到的需求中有在electron中實(shí)現(xiàn)打印pdf文件的功能先慷。從網(wǎng)上找了很多第三方工具骡男，基本上是在頁(yè)面中打開pdf，然后打印web頁(yè)面恃锉。這固然可以實(shí)現(xiàn)打印功能，但是打印的實(shí)際上只是個(gè)web頁(yè)面呕臂，而非真正的pdf源文件破托。

該方法實(shí)際上是通過(guò)node執(zhí)行命令來(lái)調(diào)用SumatraPDF從而打印pdf文件，所以我們需要把SumatraPDF目錄直接放在項(xiàng)目static（vue-cli3為public）目錄下

1.png

完整需求為通過(guò)接口獲取pdf文件流歧蒋，打印pdf土砂。（這里只講了打印pdf部分）
完整思路如下：

1.渲染進(jìn)程調(diào)接口獲取pdf文件流

import QS from 'qs'

const download = (url, query, cb, type) => {
  var xhr = new XMLHttpRequest()
  xhr.open(
    "GET",
    `${axios.defaults.baseURL}${url}?${QS.stringify(query)}`,
    true
  )
  xhr.responseType = "blob"
  xhr.setRequestHeader("Access-Token", sessionStorage.getItem("token"))
  xhr.onload = function() {
    if (this.status == 200) {
      var blob = new Blob([this.response], {
        type: "application/pdf;charset=utf-8",
      })
      //生成URL
      let href = window.URL.createObjectURL(blob)
      if (cb) {
        // 有回調(diào)，根據(jù)type在回調(diào)中傳入blob對(duì)象或url
        if (type == "blob") {
          cb(blob)
        } else {
          cb(href)
        }
      } else {
        // 無(wú)回調(diào)谜洽，直接導(dǎo)出下載
        let link = document.createElement("a")
        link.download = "波形.pdf"
        link.href = href
        link.click()
      }
    }
  }
  xhr.send()
}

const printReport = (p, cb, type = "url") => download(`report/worklist/print`, p, cb, type)

2.將pdf文件流轉(zhuǎn)為Buffer格式（先轉(zhuǎn)為blob對(duì)象萝映，然后通過(guò)FileReader轉(zhuǎn)為Buffer）

exportReport(
    {},
    (blob) => {
        let self = this
        let reader = new FileReader()
        reader.readAsDataURL(blob)
        reader.addEventListener('loadend', () => {
            // 通知主進(jìn)程打印
            ipc.send('printPDF', {
                baseCode: Buffer.from(reader.result.split('base64,')[1], 'base64'),
            })
        })
    },
    'blob'
)

3.渲染進(jìn)程與主進(jìn)程通信，發(fā)送Buffer到主進(jìn)程阐虚。主進(jìn)程通過(guò)fs模塊將pdf保存到本地序臂，通過(guò)child_process執(zhí)行SumatraPDF打印命令，完成打印

const cp = require('child_process');
const path = require("path");
const fs = require('fs');
const { app, ipcMain: ipc } = require("electron");

ipc.on('printPDF', (e, arg) => {
    const writeFile = () => {
        fs.writeFile('./data/waveform.pdf', arg.baseCode, { encoding: 'utf8' }, err => {
            // 失敗
            if (err) {
                // 向渲染進(jìn)程發(fā)送消息通知失敗
                e.reply('defeatedDialog', err)
            } else {
                let pdfUrl = path.join(app.getAppPath(), process.env.NODE_ENV === 'development' ? '../data/waveform.pdf' : '../../data/waveform.pdf')
                switch (process.platform) {
                    case 'darwin':
                    case 'linux':
                        cp.exec(
                            `SumatraPDF.exe -print-to-default  "${pdfUrl}"`,
                            {
                                windowsHide: true,
                                cwd: path.join(app.getAppPath(), process.env.NODE_ENV === 'development' ? '../static/SumatraPDF' : './app/static/SumatraPDF'),
                            },
                            e => {
                                if (e) {
                                    throw e
                                }
                            }
                        )
                        break
                    case 'win32':
                        cp.exec(
                            `SumatraPDF.exe -print-to-default  "${pdfUrl}"`,
                            {
                                windowsHide: true,
                                cwd: path.join(app.getAppPath(), process.env.NODE_ENV === 'development' ? '../static/SumatraPDF' : './app/static/SumatraPDF'),
                            },
                            e => {
                                fs.unlink(pdfUrl, e => {})
                                if (e) {
                                    throw e
                                }
                            }
                        )
                        break
                    default:
                        throw new Error('Platform not supported.')
                }
            }
        })
    }
    if (fs.existsSync('./data')) {
        writeFile()
    } else {
        fs.mkdir('./data', { recursive: true }, err => {
            if (err) {
                throw err
            } else {
                writeFile()
            }
        })
    }
})

代碼給大家貼出來(lái)了实束，有問(wèn)題或有改進(jìn)建議的小伙伴可以留言奥秆，我看到后會(huì)回復(fù)大家

附SumatraPDF文檔：https://www.sumatrapdfreader.org/docs/Command-line-arguments.html