electron-文件处理的应用

文件管理是桌面应用非常重要的功能，几乎所有的应用都会涉及到文件的内容。

安装依赖的库

npm install -g bower

**提示：**bower也是一个包管理，通过这个库你可以安装所有js和css的库。

安装boostrap

bower install bootstrap

安装jquery

npm install --save jquery

该章的内容是创建一个表单，输入相应的名字和Email,系统会将其保存在一个.txt文件当中，当你再次打开的时候会自动从该文件读取相应的内容。

我们需要创建一个main.js文件，并且输入下面所示的代码。

const {
    app,
    BrowserWindow
} = require('electron')
const url = require('url')
const path = require('path')
let win

function createWindow() {
    win = new BrowserWindow({
        width: 800,
        height: 600
    })
    win.loadURL(url.format({
        pathname: path.join(__dirname, 'index.html'),
        protocol: 'file',
        slashes: true
    }))
}
app.on('ready', createWindow)

同样的我们需要创建一个index.html，用来创建显示的内容。

<!DOCTYPE html>
<html>
   <head>
      <meta charset = "UTF-8">
      <title>File System</title>
      <link rel = "stylesheet" 
         href = "./bower_components/bootstrap/dist/css/bootstrap.min.css" />
      
      <style type = "text/css">
         #contact-list {
            height: 150px;
            overflow-y: auto;
         }
      </style>
   </head>
   
   <body>
      <div class = "container">
         <h1>Enter Names and Email addresses of your contacts</h1>
         <div class = "form-group">
            <label for = "Name">Name</label>
            <input type = "text" name = "Name" value = "" id = "Name" 
               placeholder = "Name" class = "form-control" required>
         </div>
         
         <div class = "form-group">
            <label for = "Email">Email</label>
            <input type = "email" name = "Email" value = "" id = "Email" 
               placeholder = "Email" class = "form-control" required>
         </div>
         
         <div class = "form-group">
            <button class = "btn btn-primary" id = "add-to-list">Add to list!</button>
         </div>
         
         <div id = "contact-list">
            <table class = "table-striped" id = "contact-table">
               <tr>
                  <th class = "col-xs-2">S. No.</th>
                  <th class = "col-xs-4">Name</th>
                  <th class = "col-xs-6">Email</th>
               </tr>
            </table>
         </div>
         
         <script src = "./view.js" ></script>
      </div>
   </body>
</html>

现在我们创建一个view.js文件。

我们创建一个函数loadAndDisplayContacts()，该函数在初始加载时会读取文件并且追加到列表当中，同时创建了一个单击事件，将当前的信息添加到列表当中。

let $ = require('jquery')
let fs = require('fs')
let filename = 'contacts'
let sno = 0

$('#add-to-list').on('click', () => {
   let name = $('#Name').val()
   let email = $('#Email').val()

   fs.appendFile('contacts', name + ',' + email + '\n')

   addEntry(name, email)
})

function addEntry(name, email) {
   if(name && email) {
      sno++
      let updateString = '<tr><td>'+ sno + '</td><td>'+ name +'</td><td>' 
         + email +'</td></tr>'
      $('#contact-table').append(updateString)
   }
}

function loadAndDisplayContacts() {  
   
   //Check if file exists
   if(fs.existsSync(filename)) {
      let data = fs.readFileSync(filename, 'utf8').split('\n')
      
      data.forEach((contact, index) => {
         let [ name, email ] = contact.split(',')
         addEntry(name, email)
      })
   
   } else {
      console.log("File Doesn\'t Exist. Creating new file.")
      fs.writeFile(filename, '', (err) => {
         if(err)
            console.log(err)
      })
   }
}

loadAndDisplayContacts()

最终显示的效果

electron-文件处理的应用

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