> For the complete documentation index, see [llms.txt](https://jack80342.gitbook.io/thymeleaf/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jack80342.gitbook.io/thymeleaf/i.-using-thymeleaf/2-the-good-thymes-virtual-grocery/2.1-a-website-for-a-grocery.md).

# 2.1 杂货店网站

为了更好地解释在使用Thymeleaf处理模版时涉及的概念，本教程将会使用一个演示应用。你可以从项目的网站上下载⏬。

这个应用是一个虚构的杂货店的网站。它将会提供我们许多场景，来展示Thymeleaf的诸多特性。

首先，我们需要为应用准备一套简单的模型实体：通过创建`订单`卖给`顾客`的`产品`。我们也会管理与那些`产品`有关的`评论`。

![Example application model](http://www.thymeleaf.org/doc/tutorials/3.0/images/usingthymeleaf/gtvg-model.png)

我们的应用也会🈶️一个非常简单的服务层，由包含如下方法的`服务`对象组成：

```java
public class ProductService {

    ...

    public List<Product> findAll() {
        return ProductRepository.getInstance().findAll();
    }

    public Product findById(Integer id) {
        return ProductRepository.getInstance().findById(id);
    }

}
```

在网络层，我们的应用将会🈶️一个过滤器。它会依据请求的URL，分配执行启用Thymeleaf的命令：

```java
private boolean process(HttpServletRequest request, HttpServletResponse response)
        throws ServletException {

    try {

        // This prevents triggering engine executions for resource URLs
        if (request.getRequestURI().startsWith("/css") ||
                request.getRequestURI().startsWith("/images") ||
                request.getRequestURI().startsWith("/favicon")) {
            return false;
        }


        /*
         * Query controller/URL mapping and obtain the controller
         * that will process the request. If no controller is available,
         * return false and let other filters/servlets process the request.
         */
        IGTVGController controller = this.application.resolveControllerForRequest(request);
        if (controller == null) {
            return false;
        }

        /*
         * Obtain the TemplateEngine instance.
         */
        ITemplateEngine templateEngine = this.application.getTemplateEngine();

        /*
         * Write the response headers
         */
        response.setContentType("text/html;charset=UTF-8");
        response.setHeader("Pragma", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);

        /*
         * Execute the controller and process view template,
         * writing the results to the response writer. 
         */
        controller.process(
                request, response, this.servletContext, templateEngine);

        return true;

    } catch (Exception e) {
        try {
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        } catch (final IOException ignored) {
            // Just ignore this
        }
        throw new ServletException(e);
    }

}
```

这是我们的`IGTVGController`接口：

```java
public interface IGTVGController {

    public void process(
            HttpServletRequest request, HttpServletResponse response,
            ServletContext servletContext, ITemplateEngine templateEngine);    

}
```

现在我们要做的就是创建`IGTVGController`接口的实现，从服务中取回数据，并使用`ITemplateEngine`对象处理模版。

最后，它看起来就像这样：

![Example application home page](http://www.thymeleaf.org/doc/tutorials/3.0/images/usingthymeleaf/gtvg-view.png)

但是，先让我们看看那个模版引擎是怎么被初始化的。


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