问题

$.ajax({
  url: "",
  method: "",
  data: { },
  success: function(data) {
    ~~~~
  }
});

// controller
// ...
model.addAttribute("user", userDTO);
// ...

// html(thymeleaf)
${user.name}

在导入数据时，上述两种情况有什么区别？

<details>
<summary>英文:</summary>

	  $.ajax({
		url: "",
		method: "",
		data: { },
		success: function(data) {
		  ~~~~
		}
	  });

// controller
// ...
model.addAttribute("user", userDTO);
// ...

// html(thymeleaf)
${user.name}

When importing data, what is the difference between the above two cases?

</details>


# 答案1
**得分**: 0

你的第一个示例表示一个在Web浏览器的JavaScript引擎上执行的jQuery AJAX方法。'success'函数将会**异步地**被调用，携带着响应负载，并且JavaScript再次负责处理这些数据。你可以拥有多个这样的异步操作，而无需重新加载整个页面。

你的第二个示例代表了后端的服务器端MVC往返。从意义上讲，这是一个**同步**操作，因为发起请求的Web浏览器会在操作描述的过程完成之前阻塞，以便接收返回的解析过的HTML。

它遵循了在Spring Framework中实现的MVC范 paradigm，其中[Thymeleaf][1]是表示**View**（MVC中的'V'）的模板引擎。`model.addAttribute("user", userDTO)`将**Model**（MVC中的'M'）绑定在一起，以便它可以填充模板的占位符。两者都在Controller中汇集在一起（MVC中的'C'），该控制器接收前端请求，并负责收集模型并填充模板，将解析后的最终HTML作为响应返回（实际上，在Spring MVC中，控制器通常返回视图名称，框架会负责调用注册的模板引擎）。**所有这些活动都发生在后端**。

  [1]: https://www.thymeleaf.org/

<details>
<summary>英文:</summary>

Your first example represents a JQuery AJAX method that executes on the JS engine of the Web-browser. The &#39;success&#39; function will be called **asynchronously** with the response payload and again JS is responsible to do whatever is needed with this data. You can have multiple such asynchronous operations without the need of reloading/refreshing the whole page.

Your second example represents the server-side MVC roundtrip in the backend. This is a **synchronous** operation in the sense that the Web-browser that fires the request blocks until the operation described below completes so that it receives back the parsed HTML. 

It follows the MVC paradigm implemented in Spring Framework where [Thymeleaf][1] is the templating engine representing the **View** (the &#39;V&#39; in MVC). The `model.addAttribute(&quot;user&quot;, userDTO)` is tying the **Model** (the &#39;M&#39; in MVC) so that it can be filled in the placeholders of the template. Both are brought together in the Controller (the &#39;C&#39; in MVC) that is receiving the front-end request and is responsible for gathering the **Model**s and filling the template returning as a response the parsed final HTML (in fact the Controller in Spring MVC is normally returning the View name and the framework takes care to invoke the registered Template engine). **All this activity happens in the backend**.




  [1]: https://www.thymeleaf.org/

</details>