javaweb-thymeleaf，加载jar包---视图基础

1.加载完thymeleaf的jar包

将thymeleaf的jar包复制到项目下lib文件夹中

右击lib文件夹，点击Add as librarb...

打开Project Structure，找到Modules，点击加号，点击Library，找到lib，完成添加

2.创建ViewBaseServlet类,并把以下代码放入类中

import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.WebContext;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ViewBaseServlet extends HttpServlet {

    private TemplateEngine templateEngine;

    @Override
    public void init() throws ServletException {

        // 1.获取ServletContext对象
        ServletContext servletContext = this.getServletContext();

        // 2.创建Thymeleaf解析器对象
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(servletContext);

        // 3.给解析器对象设置参数
        // ①HTML是默认模式，明确设置是为了代码更容易理解
        templateResolver.setTemplateMode(TemplateMode.HTML);

        // ②设置前缀
        String viewPrefix = servletContext.getInitParameter("view-prefix");

        templateResolver.setPrefix(viewPrefix);

        // ③设置后缀
        String viewSuffix = servletContext.getInitParameter("view-suffix");

        templateResolver.setSuffix(viewSuffix);

        // ④设置缓存过期时间（毫秒）
        templateResolver.setCacheTTLMs(60000L);

        // ⑤设置是否缓存
        templateResolver.setCacheable(true);

        // ⑥设置服务器端编码方式
        templateResolver.setCharacterEncoding("utf-8");

        // 4.创建模板引擎对象
        templateEngine = new TemplateEngine();

        // 5.给模板引擎对象设置模板解析器
        templateEngine.setTemplateResolver(templateResolver);

    }

    protected void processTemplate(String templateName, HttpServletRequest req, HttpServletResponse resp) throws IOException {
        // 1.设置响应体内容类型和字符集
        resp.setContentType("text/html;charset=UTF-8");

        // 2.创建WebContext对象
        WebContext webContext = new WebContext(req, resp, getServletContext());

        // 3.处理模板数据
        templateEngine.process(templateName, webContext, resp.getWriter());
    }
}

 3.在web.xml文件中添加配置

<!--    配置前缀 view-prefix   配置后缀 view-suffix　　前后缀可以随意改变-->
<!--　　物理视图=配置前缀+逻辑视图+配置后缀　　-->
    <context-param>
        <param-name>view-prefix</param-name>
        <param-value>/</param-value>
    </context-param>
    <context-param>
        <param-name>view-suffix</param-name>
        <param-value>.html</param-value>
    </context-param>

4.创建html页面

　　在html中的thymeleaf语法：

　　th:if=""　　//if语句
　　th:unless=""　　//else语句
　　th:ecah=""　　//for语句
　　th:text=""　　//文本语句

<tr th:if="${#lists.isEmpty(session.fruitList)}">
                    <td colspan="4">对不起，库存为空！！</td>
                    </tr>
                    <!--  if是判断是否为条件真 unless是判断是否为条件假 each是叠代，从session.list中依次取出一个对象赋给fruit  -->
                    <tr th:unless="${#lists.isEmpty(session.fruitList)}" th:each="fruit : ${session.fruitList}">
                        <td th:text="${fruit.fname}"></td>

                    </tr>

5.创建一个servlet类并继承ViewBaseServlet类

　　在processTemplate方法会执行：物理视图=配置前缀+逻辑视图+配置后缀 的操作

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        FruitDAO fruitDAO = new FruitDAOImpl();
        List<Fruit> fruitList = fruitDAO.getFruitList();
        //将fruitList保存到session作用域中，
        HttpSession session = req.getSession();
        session.setAttribute("fruitList",fruitList);
//        processTemplate(String templateName, HttpServletRequest req, HttpServletResponse resp)
        super.processTemplate("demo07",req,resp);
    }