Of course! This is a classic and powerful combination for building enterprise-level web applications, especially during the mid-to-late 2000s and early 2010s. While its popularity has waned with the rise of modern front-end frameworks like React, Vue, and Angular, it's still used in many legacy systems and is a great example of how to structure a traditional server-rendered web app.
Let's break down the jQuery EasyUI + Java stack, covering what it is, how it works, a practical example, and its pros and cons.
What is the Stack?
jQuery EasyUI
jQuery EasyUI is a collection of user interface plugins built on top of the jQuery JavaScript library. Its main goal is to simplify web UI development.
- jQuery: A fast, small, and feature-rich JavaScript library. It makes things like HTML document traversal and manipulation, event handling, and animation much simpler with an easy-to-use API.
- EasyUI: Provides pre-built, themeable UI components (widgets) like DataGrids, Forms, Dialogs, Layouts, Menus, etc. You don't have to build these from scratch; you just configure them with HTML attributes or JavaScript.
The key philosophy of EasyUI is "Write Less, Do More". You can define a complex component like a data grid with just a few lines of HTML:
<!-- This single line creates a fully functional, paginated, sortable, filterable data grid! -->
<table class="easyui-datagrid" title="Users" style="width:100%;height:400px"
url="get_users.jsp" method="get"
toolbar="#toolbar" pagination="true"
rownumbers="true" fitColumns="true" singleSelect="true">
<thead>
<tr>
<th field="userid" width="50">ID</th>
<th field="name" width="50">Name</th>
<th field="email" width="50">Email</th>
</tr>
</thead>
</table>
Java (Backend)
In this stack, Java (typically running on a server like Tomcat) acts as the backend. Its responsibilities are:
- Business Logic: Handle core application logic (e.g., user authentication, order processing).
- Data Access: Interact with a database (using technologies like JDBC, JPA, or Hibernate).
- Provide Data Services: Expose endpoints (usually as Servlets or JSPs) that the jQuery EasyUI front-end can call to get data or perform actions.
The communication between the front-end and back-end is typically done using AJAX (Asynchronous JavaScript and XML), although JSON is far more common today.
How They Work Together: The Flow
The interaction follows a classic client-server model:
- Initial Request: The user types the URL of your application into their browser. The request goes to the Java backend (e.g., a
index.jspor a servlet). - Server-Side Rendering (SSR): The Java backend generates the initial HTML page. This HTML includes:
- The basic page structure (
<html>,<head>,<body>). - Links to the jQuery, EasyUI CSS, and JavaScript files.
- The HTML structure for the EasyUI components (like the
<table>example above).
- The basic page structure (
- Client-Side Initialization: The user's browser receives the HTML and loads the JavaScript and CSS files. The EasyUI JavaScript code scans the HTML, finds the elements with the
easyui-*classes, and transforms them into fully interactive, styled widgets. - Data Loading (AJAX Call): The EasyUI DataGrid, for example, sees its
url="get_users.jsp"attribute. It automatically makes an asynchronous HTTP GET request to that URL. - Backend Processing: The Java backend receives the request for
get_users.jsp.- The JSP (or the servlet it calls) executes Java code.
- This code queries the database to get the list of users.
- It formats the user data as a JSON string.
- It sends this JSON string back as the HTTP response.
- Front-Side Rendering: The EasyUI DataGrid receives the JSON response. It parses the data and dynamically renders the rows inside the table, populating it with the user information from the database. The page is now fully interactive without a full page refresh.
Practical Example: A User DataGrid
Let's build a simple page that displays a list of users in a DataGrid.
Step 1: Project Structure (using Maven)
my-app/
├── src/
│ ├── main/
│ │ ├── java/
│ │ │ └── com/
│ │ │ └── example/
│ │ │ └── controller/
│ │ │ └── UserController.java
│ │ ├── webapp/
│ │ │ ├── WEB-INF/
│ │ │ │ └── web.xml
│ │ │ ├── css/
│ │ │ │ └── easyui.css
│ │ │ ├── js/
│ │ │ │ ├── jquery.min.js
│ │ │ │ ├── jquery.easyui.min.js
│ │ │ │ └── locale/
│ │ │ │ └── easyui-lang-zh_CN.js (for Chinese)
│ │ │ └── index.jsp
│ │ └── resources/
│ │ └── META-INF/
│ │ └── persistence.xml (for JPA/Hibernate)
└── pom.xmlStep 2: The Front-End (index.jsp)
This file contains the HTML for the page and the EasyUI DataGrid.
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">jQuery EasyUI + Java Demo</title>
<!-- EasyUI CSS -->
<link rel="stylesheet" type="text/css" href="css/easyui.css">
<!-- Icon CSS (optional) -->
<link rel="stylesheet" type="text/css" href="js/themes/icon.css">
<style type="text/css">
body {
font-family: helvetica, tahoma, verdana, sans-serif;
padding: 20px;
}
</style>
</head>
<body>
<h2>User Management</h2>
<!-- The EasyUI DataGrid -->
<!-- It will automatically call the 'url' to get its data -->
<table class="easyui-datagrid" title="Users" style="width:700px;height:400px"
url="<%=request.getContextPath()%>/api/users"
method="get"
pagination="true" rownumbers="true" fitColumns="true" singleSelect="true">
<thead>
<tr>
<th field="id" width="50">ID</th>
<th field="firstName" width="100">First Name</th>
<th field="lastName" width="100">Last Name</th>
<th field="email" width="150">Email</th>
</tr>
</thead>
</table>
<!-- jQuery and EasyUI JS -->
<script type="text/javascript" src="js/jquery.min.js"></script>
<script type="text/javascript" src="js/jquery.easyui.min.js"></script>
<!-- Localization (optional) -->
<script type="text/javascript" src="js/locale/easyui-lang-zh_CN.js"></script>
</body>
</html>
Step 3: The Back-End (Java Servlet)
This servlet handles the AJAX request from the DataGrid.
package com.example.controller;
import com.example.model.User;
import com.example.service.UserService;
import com.fasterxml.jackson.databind.ObjectMapper;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;
@WebServlet("/api/users")
public class UserServlet extends HttpServlet {
private UserService userService = new UserService(); // Service layer for business logic
private ObjectMapper objectMapper = new ObjectMapper(); // For JSON conversion
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
// 1. Get data from the service layer (which talks to the DB)
List<User> users = userService.getAllUsers();
// 2. Set response content type to JSON
resp.setContentType("application/json");
resp.setCharacterEncoding("UTF-8");
// 3. Convert the Java List<User> to a JSON string and write it to the response
objectMapper.writeValue(resp.getWriter(), users);
}
}
Step 4: The Service and Model (Simplified)
-
User.java(Model/Entity):package com.example.model; public class User { private int id; private String firstName; private String lastName; private String email; // Getters and Setters... } -
UserService.java(Service Layer):package com.example.service; import com.example.model.User; import java.util.Arrays; import java.util.List; public class UserService { public List<User> getAllUsers() { // In a real app, this would query the database. // For this demo, we return a hardcoded list. return Arrays.asList( new User(1, "John", "Doe", "john.doe@example.com"), new User(2, "Jane", "Smith", "jane.smith@example.com"), new User(3, "Peter", "Jones", "peter.jones@example.com") ); } }
Pros and Cons
Pros (Why it was popular)
- Rapid Development: Drastically cuts down on front-end development time for standard UI components.
- Consistent Look and Feel: The theme system ensures a consistent UI across the entire application with minimal effort.
- Good Integration: It works seamlessly with traditional Java web technologies (JSP, Servlets, JSTL).
- Mature and Stable: It's been around for a long time, so it's well-documented and reliable.
- Low Learning Curve (for Java devs): A Java backend developer can pick up EasyUI quickly without needing deep JavaScript expertise.
Cons (Why it's less popular today)
- Outdated Architecture: It's a server-rendered architecture. Modern SPAs (Single-Page Applications) provide a much faster and more fluid user experience.
- Heavy DOM Manipulation: Like jQuery, it manipulates the DOM directly, which can be slower and harder to manage in very complex applications compared to the Virtual DOM used by React/Vue.
- Steep Learning Curve (for JS devs): The configuration is often done via custom HTML attributes (
data-options) or a mix of HTML and JavaScript, which can feel clunky and non-standard for developers used to modern frameworks. - Mobile Responsiveness: While possible, making EasyUI components truly responsive and mobile-friendly can be a challenge compared to frameworks designed with a mobile-first approach.
- Declining Community Support: The community has largely moved to modern front-end frameworks. Finding new plugins or up-to-date tutorials is harder.
Conclusion
The jQuery EasyUI + Java stack is a powerful and efficient solution for building traditional, data-driven web applications. It excels in scenarios where you need to build a functional admin panel or internal tool quickly, especially within a team of Java developers.
However, for new projects, especially those requiring a rich, interactive, and mobile-friendly user experience, the industry has shifted towards a decoupled architecture:
- Frontend: A modern JavaScript framework like React, Vue, or Angular.
- Backend: A Java REST API built with Spring Boot, which serves data exclusively in JSON format.
This modern stack offers greater flexibility, better performance, and a more robust developer ecosystem. But for maintaining or understanding legacy systems, the jQuery EasyUI + Java combination is still a very valuable skill to have.
