Spring Boot之整合视图层技术

学习笔记 : Spring Boot之整合视图层技术

简介 : 在目前的企业级应用开发中,前后端分离是趋势,但是视图技术还有一席之地. Spring Boot对视图层技术提供了很好的支持,官方推荐使用的模板引擎是Thymeleaf,也支持FreeMarker哟,需要注意的是Spring Boot官方并不推荐使用JSP技术 !

整合Thymeleaf

Thymeleaf是新一代模板引擎,类似于Velocity,FreeMarker等传统Java模板引擎.与其不同的是: Thymeleaf支持HTML原型,同时Spring Boot也提供了Thymeleaf自动化配置解决方案. 更多资料见 : https://www.thymeleaf.org/

配置Thymeleaf

Spring Boot为Thymeleaf提供了自动化配置类ThymeleafAutoConfiguration,相关的配置信息在ThymeleafProperties类中,其部分源码如下所示 :

@ConfigurationProperties(
    prefix = "spring.thymeleaf"
)
public class ThymeleafProperties {
    private static final Charset DEFAULT_ENCODING;
    public static final String DEFAULT_PREFIX = "classpath:/templates/";
    public static final String DEFAULT_SUFFIX = ".html";
    private boolean checkTemplate = true;
    private boolean checkTemplateLocation = true;
    private String prefix = "classpath:/templates/";
    private String suffix = ".html";
    private String mode = "HTML";

    ······

如果需要对默认的Thymeleaf配置参数进行自定义,那么可以直接在application.properties中进行配置哟,常见配置如下:

#是否开启缓存,开发时可设置为false,默认为true
spring.thymeleaf.cache=true
#检查模板是否存在,默认为true
spring.thymeleaf.check-template=true
#检查模板位置是否存在,默认为true
spring.thymeleaf.check-template-location=true
#模板文件编码
spring.thymeleaf.encoding=UTF-8
#模板文件位置
spring.thymeleaf.prefix=classpath:/templates/
#Content-Type配置
spring.thymeleaf.servlet.content-type=text/html
#模板文件后缀
spring.thymeleaf.suffix=.html

示例程序

1. pom.xml

   <?xml version="1.0" encoding="UTF-8"?>
   <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
   
       <!-- lookup parent from repository -->
       <parent>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-parent</artifactId>
           <version>2.1.6.RELEASE</version>
           <relativePath/>
       </parent>
       <groupId>pers.huangyuhui</groupId>
       <artifactId>view</artifactId>
       <version>0.0.1-SNAPSHOT</version>
       <name>view</name>
       <description>Demo project for Spring Boot</description>
   
       <properties>
           <java.version>11</java.version>
       </properties>
   
       <dependencies>
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-thymeleaf</artifactId>
           </dependency>
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-web</artifactId>
           </dependency>
       </dependencies>
   
   </project>

2. Book.java : 图书信息

   package pers.huangyuhui.view.bean;
   
   /**
    * @project: view
    * @description: 图书信息
    * @author: 黄宇辉
    * @date: 6/26/2019-9:24 PM
    * @version: 1.0
    * @website: https://yubuntu0109.github.io/
    */
   public class Book {
   
       private Integer id;
       private String name;
       private String author;
   
       public Book(Integer id, String name, String author) {
           this.id = id;
           this.name = name;
           this.author = author;
       }
   
       //getter and setter ...
   }

3. BookDao.java : 获取并存储图书信息

   package pers.huangyuhui.view.dao;
   
   import pers.huangyuhui.view.bean.Book;
   
   import java.util.ArrayList;
   import java.util.List;
   
   /**
    * @project: view
    * @description: 操控图书信息
    * @author: 黄宇辉
    * @date: 6/26/2019-9:41 PM
    * @version: 1.0
    * @website: https://yubuntu0109.github.io/
    */
   public class BookDao {
   
       //存储图书信息
       private static List<Book> books = new ArrayList<>();
   
       public static List<Book> getBooks() {
           Book book1 = new Book(1, "Spring", "spring-author");
           Book book2 = new Book(2, "Spring MVC", "springmvc-author");
           Book book3 = new Book(3, "MyBatis", "mybatis-author");
           Book book4 = new Book(4, "Spring Boot", "springboot-author");
           books.add(book1);
           books.add(book2);
           books.add(book3);
           books.add(book4);
           return books;
       }
   }

4. BookController.java : 操控图书信息的控制器

   package pers.huangyuhui.view.controller;
   
   import org.springframework.stereotype.Controller;
   import org.springframework.web.bind.annotation.GetMapping;
   import org.springframework.web.servlet.ModelAndView;
   import pers.huangyuhui.view.dao.BookDao;
   
   /**
    * @project: view
    * @description: 操控图书信息的控制器
    * @author: 黄宇辉
    * @date: 6/26/2019-9:26 PM
    * @version: 1.0
    * @website: https://yubuntu0109.github.io/
    */
   @Controller
   public class BookController {
   
       @GetMapping("/getBookList")
       public ModelAndView books() {
           ModelAndView modelAndView = new ModelAndView();
           modelAndView.addObject("books", BookDao.getBooks());
           modelAndView.setViewName("bookList");
           return modelAndView;
       }
   
   }

5. bookList.html : 展示图书列表信息的页面

   <!DOCTYPE html>
   <!-- 导入Thymeleaf的名称空间 -->
   <html lang="en" xmlns:th="http://www.thymeleaf.org">
   <head>
       <meta charset="UTF-8">
       <title>图书信息列表页面-Thymeleaf</title>
   </head>
   <body>
   <table border="1">
       <tr>
           <td>图书编号</td>
           <td>图书名称</td>
           <td>图书作者</td>
       </tr>
       <tr th:each="book:${books}">
           <td th:text="${book.id}"></td>
           <td th:text="${book.name}"></td>
           <td th:text="${book.author}"></td>
       </tr>
   </table>
   </body>
   </html>

整合FreeMarker

FreeMarker是一个非常古老的模板引擎,可以用在Web环境或者非Web环境中. 与Thymeleaf不同的是FreeMarker需要经过解析才能够在浏览器中展示出来. 更多资料见 : https://freemarker.apache.org/

配置FreeMarker

Spring Boot对FreeMarker也提供了配置类FreeMarkerAutoConfiguration,相关的配置属性在FreeMarkerProperties中,其部分源码如下所示 :

@ConfigurationProperties(
    prefix = "spring.freemarker"
)
public class FreeMarkerProperties extends AbstractTemplateViewResolverProperties {
    public static final String DEFAULT_TEMPLATE_LOADER_PATH = "classpath:/templates/";
    public static final String DEFAULT_PREFIX = "";
    public static final String DEFAULT_SUFFIX = ".ftl";
    private Map<String, String> settings = new HashMap();
    private String[] templateLoaderPath = new String[]{"classpath:/templates/"};
    private boolean preferFileSystemAccess = true;

    ······

如果需要对默认的FreeMarker配置参数进行自定义,那么可以直接在application.properties中进行配置哟,常见配置如下:

#HttpServletRequest的属性是否可以覆盖controller中model的同名项
spring.freemarker.allow-request-override=false
#HttpSession的属性是否可以覆盖controller中的model的同名项
spring.freemarker.allow-session-override=false
#是否开启缓存
spring.freemarker.cache=false
#模板文件编码
spring.freemarker.charset=UTF-8
#是否检查模板位置
spring.freemarker.check-template-location=true
#Content-type的值
spring.freemarker.content-type=text/html
#是否将HttpServletRequest中的属性添加到Model中
spring.freemarker.expose-request-attributes=false
#是否将HttpSession中的属性添加到Model中
spring.freemarker.expose-session-attributes=false
#模板文件后缀
spring.freemarker.suffix=.ftl
#模板文件位置
spring.freemarker.template-loader-path=classpath:/templates/

示例程序

1. Book.java,BookDao.java,BookController.java程序与Thymeleaf示例程序相同,此处略写 …

2. 在pom.xml中需添加FreeMarker依赖

   <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-freemarker</artifactId>
   </dependency>

3. bookList.html : 展示图书列表的页面

   <!DOCTYPE html>
   <html lang="en">
   <head>
       <meta charset="UTF-8">
       <title>图书列表信息页面-FreeMarker</title>
   </head>
   <body>
   <table border="1">
       <tr>
           <td>图书编号</td>
           <td>图书名称</td>
           <td>图书作者</td>
       </tr>
       <!-- 若model中的books不为空并且books中有数据,则遍历books集合  -->
       <#if books ??&&(books?size>0)>
           <#list books as book>
               <tr>
                   <td>${book.id}</td>
                   <td>${book.name}</td>
                   <td>${book.author}</td>
               </tr>
           </#list>
       </#if>
   </table>
   </body>
   </html>

整合JSP

Spring Boot官方并不推荐使用JSP技术! 但是小哥是个念旧的孩纸,来学习一波呗😁 ~

1. Book.java,BookDao.java,BookController.java程序与Thymeleaf示例程序相同,此处略写 …

2. 在pom.xml中需添加使用JSP所需的依赖

   <!-- JSTL -->
   <dependency>
       <groupId>javax.servlet</groupId>
       <artifactId>jstl</artifactId>
   </dependency>
   <!-- 用于编译JSP -->
   <dependency>
       <groupId>org.apache.tomcat.embed</groupId>
       <artifactId>tomcat-embed-jasper</artifactId>
       <scope>provided</scope>
   </dependency>

3. application.properties配置文件中用于解析视图的代码

   spring.mvc.view.prefix=/WEB-INF/jsp/
   spring.mvc.view.suffix=.jsp

4. bookList.jsp : 展示图书列表信息的页面

   <%@ page contentType="text/html;charset=UTF-8" %>
   <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
   <html>
   <head>
       <title>图书列表信息页面-JSP</title>
   </head>
   <body>
   <table border="1">
       <tr>
           <td>图书编号</td>
           <td>图书名称</td>
           <td>图书作者</td>
       </tr>
       <c:forEach items="${books}" var="book">
       <tr>
           <td>${book.id}</td>
           <td>${book.name}</td>
           <td>${book.author}</td>
       </tr>
       </c:forEach>
   </body>
   </html>

5. 程序运行结果(以上三个示例程序运行结果大同小异哟)