Ext JS动态加载JavaScript创建窗体的方法

2019-11-20 09:37:22

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JavaScript不需要编译即可运行，这让JavaScript构建的应用程序可以变得很灵活。我们可以根据需要动态从服务器加载JavaScript脚本来创建和控制UI来与用户交互。下面结合Ext JS来说明如何从服务器上动态加载JS脚本来动态创建窗体。
1 项目结构：
项目结构如下：其中GetJSUI一般处理程序用来从数据库表中抓取UI配置，并返回到客户端；Contents文件夹下用HTML文件和JS库等。

2 数据库表结构
可以用下面的SQL在MSSQL中创建表，其中JavaScriptContent字段存储具体的JS脚本。

CREATE TABLE [dbo].[Ext_Dynamic_Form]( [ID] [nvarchar](50) NOT NULL, [UniName] [nvarchar](50) NULL, [JavaScriptContent] [nvarchar](4000) NULL, [Memo] [nvarchar](200) NULL, CONSTRAINT [PK_Ext_Dynamic_Form] PRIMARY KEY CLUSTERED ( [ID] ASC)) ON [PRIMARY]

创建好后，可以初始化数据：

4 GetJSUI 编程

using System;using System.Collections.Generic;using System.Linq;using System.Web;using CMCloudDBHelper;namespace extjs6.Services{ /// <summary> /// author:jackwangcumt /// </summary> public class GetJSUI : IHttpHandler { public void ProcessRequest(HttpContext context) {  string js = "";  context.Response.ContentType = "text/plain";  //context.Response.ContentType = "text/javascript";  CMCDataAccess da = new CMCDataAccess();  string SQLForJS = "select * FROM Ext_Dynamic_Form where ID='006'";  System.Data.DataTable dt= da.GetDataTable(SQLForJS);  if(dt!=null)  {  if(dt.Rows.Count==1)  {   js = dt.Rows[0]["JavaScriptContent"].ToString();  }  }    //utf-8  context.Response.ContentEncoding = System.Text.Encoding.UTF8;  context.Response.Write(js); } public bool IsReusable {  get  {  return false;  } } }}

5 主界面html

<html><head> <title>Dynamically generate forms from server javascript</title> <!-- Library Files --> <meta http-equiv="X-UA-Compatible" content="IE=edge" charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no"> <script type="text/javascript" src="ext6/ext-all-debug.js"></script> <link rel="stylesheet" type="text/css" href="ext6/classic/theme-triton/resources/theme-triton-all-debug.css"> <script type="text/javascript" src="ext6/classic/theme-triton/theme-triton-debug.js"></script> <script type="text/javascript"> //load *.js file from server function loadScript(url, callback) { var script = document.createElement("script") script.type = "text/javascript"; if (script.readyState) { //IE script.onreadystatechange = function() { if (script.readyState == "loaded" ||  script.readyState == "complete") {  script.onreadystatechange = null;  callback(); } }; } else { //Others script.onload = function() { callback(); }; } script.src = url; document.getElementsByTagName("head")[0].appendChild(script); } //load js text from server function loadScriptSrc(js, callback) { var script = document.createElement("script") script.type = "text/javascript"; //script.async = true; if (script.readyState) { //IE script.onreadystatechange = function() { if (script.readyState == "loaded" ||  script.readyState == "complete") {  script.onreadystatechange = null;  callback(); } }; } else { //Others script.onload = function() { callback(); }; }  script.text = js; console.log(script); document.getElementsByTagName("head")[0].appendChild(script); //不能少 callback(); } //Ext JS 6 Ext.onReady(function() { //https://www.sencha.com/forum/showthread.php?268193-How-to-load-content-dynamically-for-tabpanel var pmain = Ext.widget('panel', { renderTo: document.body, height: 800, width: 800, layout: 'border', items: [{ title: 'West', region: 'west', width: 200, collapsible: true }, { xtype: 'tabpanel', region: 'center', items: [{  title: 'First Tab',  itemId: 'tab01', }, {  title: 'Second Tab',  layout: 'fit',  loader: {  url: 'Form.json',  autoLoad: true,  renderer: 'component'  } }] }] }); //ajax config var reqConfig = {  url: '../Services/GetJSUI.ashx',  method: 'get',  callback: function (options, success, response) {    // var msg = ['success:', success, '/n', 'data:', response.responseText];  // alert(msg.join(''));  loadScriptSrc(response.responseText, function() {  Ext.Msg.alert("loaded js","从服务器加载JS完成");  var gp = Ext.create("gpView");   Ext.ComponentQuery.query('#tab01')[0].add(gp);  });  } }; Ext.Ajax.request(reqConfig); //loadScript("dynamicLoadJS2.js", function() { // Ext.Msg.alert("loaded"); // var gp = Ext.create("gpView"); // //console.log(gp); // //gp.body.renderTo(pmain); // // Ext.ComponentQuery.query('#tab01')[0].add({ // // html: 'Oh, Hello.' // // }); // Ext.ComponentQuery.query('#tab01')[0].add(gp); //}); }); </script></head><body></body></html>

6 运行

这样我们可以做一个主框架，然后构建菜单和权限等通用体系，通过在数据库中配置菜单及UI，可以动态扩展应用。