Thymeleaf - 视图模板技术

1.添加thymeleaf的jar包

2. 新建一个Servlet类ViewBaseServlet

package com.atguigu.myssm.myspringmvc;

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

<!-- 配置上下文参数 -->
<!-- 前缀 -->
    <context-param>
        <param-name>view-prefix</param-name>
        <param-value>/</param-value>
    </context-param>
<!-- 后缀 -->
    <context-param>
        <param-name>view-suffix</param-name>
        <param-value>.html</param-value>
    </context-param>

4.使得我们的Servlet继承ViewBaseServlet

package com.atguigu.fruit.servlets;

import com.atguigu.fruit.dao.FruitDAO;
import com.atguigu.fruit.dao.impl.FruitDAOImpl;
import com.atguigu.fruit.pojo.Fruit;
import com.atguigu.myssm.myspringmvc.ViewBaseServlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.List;

//Servlet从3.0版本开始支持注解方式的注册
@WebServlet("/index")
public class IndexServlet extends ViewBaseServlet {
    @Override
    public void doGet(HttpServletRequest request , HttpServletResponse response)throws IOException, ServletException {
        FruitDAO fruitDAO = new FruitDAOImpl();
        List<Fruit> fruitList = fruitDAO.getFruitList();
        //保存到session作用域
        HttpSession session = request.getSession() ;
        session.setAttribute("fruitList",fruitList);
        //此处的视图名称是 index
        //那么thymeleaf会将这个 逻辑视图名称 对应到 物理视图 名称上去
        //逻辑视图名称 ：   index
        //物理视图名称 ：   view-prefix + 逻辑视图名称 + view-suffix
        //所以真实的视图名称是：      /       index       .html
        super.processTemplate("index",request,response);
    }
}

5.根据逻辑视图名称 得到 物理视图名称

此处的视图名称是 index
那么thymeleaf会将这个 逻辑视图名称 对应到 物理视图 名称上去
逻辑视图名称 ： index
物理视图名称 ： view-prefix + 逻辑视图名称 + view-suffix
所以真实的视图名称是： / index .html

   super.processTemplate("index",request,response);

6.使用thymeleaf的标签

 th:if   ,  th:unless   , th:each   ,   th:text

<!--http://www.thymeleaf.org之后可出提示词-->
<html xmlns:th="http://www.thymeleaf.org">
	<head>
		<meta charset="utf-8">
		<link rel="stylesheet" href="css/index.css">
        <script language="JavaScript" src="js/index.js"></script>
	</head>
	<body>
		<div id="div_container">
			<div id="div_fruit_list">
				<p class="center f30">欢迎使用水果库存后台管理系统</p>
				<div style="border:0px solid red;width:60%;margin-left:20%;text-align:right;">
					<a th:href="@{/add.html}" style="border:0px solid blue;margin-bottom:4px;">添加新库存记录</a>
				</div>
				<table id="tbl_fruit">
					<tr>
						<th class="w20">名称1</th>
						<th class="w20">单价</th>
						<th class="w20">库存</th>
						<th>操作</th>
					</tr>
<!--					th:if-->
					<tr th:if="${#lists.isEmpty(session.fruitList)}">
						<td colspan="4">对不起，库存为空！</td>
					</tr>
<!--					th:unless-->
					<tr th:unless="${#lists.isEmpty(session.fruitList)}" th:each="fruit : ${session.fruitList}">
						<td><a th:text="${fruit.fname}" th:href="@{/edit.do(fid=${fruit.fid})}">苹果</a></td>
						<td th:text="${fruit.price}">5</td>
						<td th:text="${fruit.fcount}">20</td>
						<!-- <td><img src="imgs/del.jpg" class="delImg" th:οnclick="'delFruit('+${fruit.fid}+')'"/></td> -->
                        <td><img src="imgs/del.jpg" class="delImg" th:onclick="|delFruit(${fruit.fid})|"/></td>
					</tr>
				</table>
			</div>
		</div>
	</body>
</html>