5, View parsing and template engine
- SpringBoot does not support jsp by default, so it is necessary to introduce third-party template engine technology to realize page rendering
1. Introduction to Thymeleaf
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Modern, server-side Java template engine
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Use in SpringBoot
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Introducing a starter (scenario launcher)
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> -
The prefix and suffix have been specified in SpringBoot under the temlates folder
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To introduce a noun space into an html file:
xmlns:th="http://www.thymeleaf.org"
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2. Expression
| Expression name | grammar | describe |
|---|---|---|
| Variable value | ${xxx} | Get data in request domain, Session domain and object |
| Select variable | *{xxx} | Get context object value |
| news | #{xxx} | Get international equivalent |
| link | @{xxx} | Generate link |
| Fragment Expression | ~{xxx} | It is equivalent to jsp:include, which introduces public page fragments |
3. Literal quantity
- Use single quotation marks for text values
- Null is used for null values
4. Text operation
- String splicing+
- Variable replace The name is ${name}
5. Boolean operation
- Operators: and or
- Unary operation:, not
6. Comparison operator
- >, <, > =, < = (GT, lt, Ge, le * *) * equation: = == ( eq , ne )
7. Iteration
<tr th:each="prod : ${prods}">
<td th:text="${prod.name}">Onions</td>
<td th:text="${prod.price}">2.41</td>
<td th:text="${prod.inStock}? #{true} : #{false}">yes</td>
</tr>
8. Judge
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th:if
<a href="comments.html" th:href="@{/product/comments(prodId=${prod.id})}" th:if="${not #lists.isEmpty(prod.comments)}">view</a> -
th:switch
<div th:switch="${user.role}"> <p th:case="'admin'">User is an administrator</p> <p th:case="#{roles.manager}">User is a manager</p> <p th:case="*">User is some other thing</p> </div>
9. Inline writing
- [[${session.loginUser.userName}]]
- Use [[]] to get rid of the shackles of the label
10. Extract public parts
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<body> <div th:insert="footer :: copy"></div> <div th:replace="footer :: copy"></div> <div th:include="footer :: copy"></div> </body>
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<body> <div> <footer> © 2011 The Good Thymes Virtual Grocery </footer> </div> <footer> © 2011 The Good Thymes Virtual Grocery </footer> <div> © 2011 The Good Thymes Virtual Grocery </div> </body>
11. View analysis principle
- In the process of target method processing, all data will be placed in ModelAndViewContainer, including data and view address
- The parameter of the method is a custom type object (determined from the request parameter), and put it back in the ModelAndViewContainer
- Modelandview (data and view address) is returned after the execution of any target method
- processDispatchResult handles the dispatch result (how the page responds)
- render(mv,request,response): perform page rendering logic
- Return the value to the View object according to the String of the method [defines the rendering logic of the page]
- All input parsers try to see if they can get to the View object based on the current return value
- Get redirect: / main -- > thymeleaf new redirectview()
- Content negotiation viewresolver quinoa contains all of the following parsers. Internally, it still uses all of the following views to parse the view objects
- view.render(mv,getModelInternal(),request,response): the view object calls the custom render to render the page
- RedirectView: how to render [redirect to a page]
- Get destination url address
- response.sendRedirect(encodedURL)
- RedirectView: how to render [redirect to a page]
- Return the value to the View object according to the String of the method [defines the rendering logic of the page]
- render(mv,request,response): perform page rendering logic
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View resolution:
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The return value starts with forward: new internalresourceview (forwardurl) - > forward
request.getRequestDispatcher(path).forward(request,response)
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The return value starts with redirect: new redirectview() -- > render is redirect
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The return value is a normal string: new ThymeleafView()
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