Day-06 thymeleaf和三层模型

最新推荐文章于 2025-09-13 12:59:37 发布

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本文详细介绍了Thymeleaf在Java Web中的应用，从MVC模型讲解到条件渲染，包括视图解析、域对象操作和OGNL表达式的运用，是SpringBoot下高效模板引擎的实践指南。

文章目录

01-mvc模型(掌握)

为什么？
- 现在，会在java代码编写html代码用于渲染页面，这明显不合理；但是，也无法在html文件中使用java代码中的数据。
mvc模型
- C : controller,控制器 , java程序
  - ①处理请求
  - ②调度页面
- M : model,模型 , java数据(javabean、基本类型、String…)
  - ①封装数据
- V : view , 视图 , html程序
  - ①渲染页面
- 将模型渲染视图使用thymeleaf技术。

02-thymeleaf概述(掌握)

概述
- Thymeleaf是一款用于渲染XML/XHTML/HTML5内容的模板引擎。类似JSP，Velocity，FreeMaker 等，它也可以轻易的与Spring MVC等Web框架进行集成作为Web应用的模板引擎。它的主要作用是在静态页面上渲染显示动态数据
特点
- SpringBoot官方推荐使用的视图模板技术，和SpringBoot完美整合。

03-物理视图和逻辑视图(掌握)

概述
- 物理视图：请求转发到一个资源时使用的绝对路径
- 逻辑视图：物理视图=视图前缀+逻辑视图+视图后缀
  - 视图前缀：物理视图中最大的公共前缀
  - 视图后缀：物理视图中最大的公共后缀（后缀名）
举例

04-thymeleaf入门(掌握)

开发步骤
- ①引入thymeleaf的相关jar包
- ②编写web.xml
  - 配置视图前缀
  - 配置视图后缀
- ③定义ViewBaseServlet类
- ④定义Servlet类继承ViewBaseServlet类
- ⑤编写html页面
  - 使用thymeleaf渲染页面
①引入thymeleaf的相关jar包

②编写web.xml

<!--视图前缀-->
<context-param>
    <param-name>view-prefix</param-name>
    <param-value>/pages/</param-value>
</context-param>

<!--视图后缀-->
<context-param>
    <param-name>view-suffix</param-name>
    <param-value>.html</param-value>
</context-param>

③定义ViewBaseServlet类

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);

    }


    /**
     * 执行视图
     * @param templateName : 逻辑视图
     * @param req : 请求
     * @param resp : 响应
     * @throws IOException
     */
    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());
    }
}

④定义Servlet类继承ViewBaseServlet类

@WebServlet("/demo01")
public class Demo01Servlet extends ViewBaseServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String errorMsg = "用户名已经存在!";
        req.setAttribute("errorMsg", errorMsg);
        //转发到demo01.html
        processTemplate("demo01", req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

⑤编写html页面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>04-thymeleaf入门</title>
</head>
<body>

<font color="red" th:text="${errorMsg}"></font>

</body>
</html>

注意事项
- 如果要使用thymeleaf指令，必须要通过ViewBaseServlet

05-thymeleaf修改标签内容(掌握)

概述
- 使用th:text指令修改标签内容

代码实现

@WebServlet("/demo02")
public class Demo02Servlet extends ViewBaseServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String msg = "helloworld";
        request.setAttribute("msg", msg);
        processTemplate("demo02", request, response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>05-thymeleaf修改标签内容</title>
</head>
<body>

<span th:text="${msg}"></span>

</body>
</html>

06-thymeleaf修改标签属性(掌握)

概述
- 使用"th:属性"修改标签的属性值

代码实现

@WebServlet("/demo03")
public class Demo03Servlet extends ViewBaseServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String msg = "helloworld";
        request.setAttribute("msg", msg);
        processTemplate("demo03", request, response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>06-thymeleaf修改标签属性</title>
</head>
<body>

<input type="text" th:value="${msg}">
<a th:href="${msg}">超链接</a>


</body>
</html>

07-thymeleaf解析url(掌握)

代码实现1 : 不带请求参数

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>07-thymeleaf解析url</title>

    <!--不带参数的URL-->
</head>
<body>

<a href="/day06/demo04">请求Demo04Servlet</a>

<a th:href="@{/demo04}">请求Demo04Servlet</a>


</body>
</html>

代码实现2 : 携带请求参数

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>07-thymeleaf解析url</title>

    <!--不带参数的URL-->
</head>
<body>

<a href="/day06/demo05?msg=aaa&msg2=bbb">请求Demo04Servlet</a>
<a th:href="@{/demo05(msg=aaa,msg2=bbb)}">请求Demo04Servlet</a>

</body>
</html>

08-thymeleaf操作域对象(掌握)

域对象
- ServletRequest
- HttpSession
- ServletContext

代码实现

@WebServlet("/demo06")
public class Demo06Servlet extends ViewBaseServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //当前请求有效
        request.setAttribute("msg1","request");
        //当前会话有效
        request.getSession().setAttribute("msg2","session");
        //当前项目有效
        getServletContext().setAttribute("msg3","servletContext");
        processTemplate("demo06",request,response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>08-thymeleaf操作域对象</title>
</head>
<body>

<span th:text="${msg1}"></span>
<span th:text="${session.msg2}"></span>
<span th:text="${application.msg3}"></span>


</body>
</html>

09-OGNL表达式(掌握)

概述
- OGNL : Object-Graph Navigation Language : 对象-图导航语言
OGNL

10-OGNL使用(掌握)

代码实现

@WebServlet("/demo07")
public class Demo07Servlet extends ViewBaseServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Student student = new Student();

        student.setStudentName("樊育东");


        student.setSubject(new Subject("java"));

        List<School> schoolList = new ArrayList<>();
        schoolList.add(new School("尚大幼儿园"));
        schoolList.add(new School("尚大小学"));
        schoolList.add(new School("尚大中学"));
        schoolList.add(new School("尚大大学"));
        student.setSchoolList(schoolList);

        Map<String, Teacher> teacherMap = new HashMap<>();
        teacherMap.put("t1", new Teacher("xiaoqiu"));
        teacherMap.put("t2", new Teacher("oldqiu"));
        student.setTeacherMap(teacherMap);

        request.setAttribute("student", student);
        processTemplate("demo07", request, response);


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>10-OGNL使用</title>
</head>
<body>

姓名:
    <span th:text="${student.studentName}"></span>

学科名称:
    <span th:text="${student.subject.subjectName}"></span>

第一个学校名称 :
    <span th:text="${student.schoolList[0].schoolName}"></span>

老师姓名:
    <span th:text="${student.teacherMap.t2.teacherName}"></span>


</body>
</html>

11-thymeleaf条件渲染(掌握)

概述
- 使用th:if、th:unless指令来进行条件渲染。

代码实现

@WebServlet("/demo08")
public class Demo08Servlet extends ViewBaseServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        boolean flag = false;
        request.setAttribute("flag", flag);
        processTemplate("demo08", request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>11-thymeleaf条件渲染</title>
</head>
<body>


<span th:if="${flag}">
    这是一个span if
</span>

<span th:unless="${flag}">
    这是一个span  unless
</span>



</body>
</html>