Spring Boot的web开发（1）

Spring Boot提供了spring-boot-starter-web（嵌入tomcat和Spring MVC的依赖）为Web开发做支持。

Thymeleaf基础知识

Thymeleaf是一个java类库，是一个xml/xhtml/html5的模板引擎，可以作为MVC的Web应用的View层。提供了额外的模块与Spring MVC集成，可以使用Thymeleaf完全替代jsp。

Thymeleaf网站：http://www.thymelead.org

1.引入Thymeleaf，代码：

<htmlxmlns:th="http://www.thymeleaf.org">

<head>

<metacontent="text/html;charset=UTF-8"/>

<linkth:src="@{bootstrap/css/bootstrap.min.css}"rel="stylesheet"/>

<linkth:src="@{bootstrap/css/bootstrap-theme.min.css}"rel="stylesheet"/>

</head>

<body>

<scriptth:src="@{jquery-1.10.2.min.js}"type="text/javascript"></script>

<scriptth:src="@{bootstrap/js/bootstrap.min.js}"></script>

</body>

</html>

2.访问Model的数据

<divclass="panel panel-primary">

<divclass="panel-heading">

<h3class="panel-title"></h3>

</div>

<divclass="panel-body">

<spanth:text="${singlePerson.name}}"></span>

</div>

3.model中的数据迭代

<divclass="panel panel-primary">

<divclass="panel-heading">

<h3class="panel-title">列表</h3>

</div>

<divclass="panel-body">

<ulclass="list-group">

<liclass="list-group-item"th:each="person:${people}">

<spanth:text="${person.name}"></span>

</li>

</ul>

</div>

4.数据判断

<divth:if="${not #lists.isEmpty(people)}">

<!--通过使用${not #lists.isEmpty(people)}表达式判断peoples是否为空。

Thymeleaf支持>、<、>=、<=、==、!=作为比较条件，同时也支持将SpringEL表达式语言用于条件中-->

<divclass="panel panel-primary">

<divclass="panel-heading">

<h3class="panel-title">列表</h3>

</div>

<divclass="panel-body">

<ulclass="list-group">

<liclass="list-group-item"th:each="person:${people}">

<spanth:text="${person.name}"></span>

</li>

</ul>

</div>

5.在javascript中访问Model

<scriptth:inline="javascript">

//通过th:inline="javascript"添加到script标签，这样Javascript代码即可访问model属性

//通过[[${}}]]格式获取实际的值

varsingle=[[${singlePerson}]];

console.log(single.name+"/"+single.age)

</script>

html通过按钮获得model的值

<liclass="list-group-item"th:each="person:${people}">

<spanth:text="${person.name}"></span>

<buttonclass="btn"th:onclick="'getName(\''+${person.name}+'\');'"></button>

</li>

与Spring MVC集成

在Spring MVC中，集成模板引擎需要定义ViewResolver,而ViewResolver需要定义一个View

例如：

@Bean//映射路径和实际页面的位置

public InternalResourceViewResolver viewResolver() {

InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();

viewResolver.setPrefix("/WEB-INF/classes/views/");

viewResolver.setSuffix(".jsp");

viewResolver.setViewClass(JstlView.class);

return viewResolver;

}

Thymeleaf定义了org.thymeleaf.spring4.view.ThymeleafView和org.thymeleaf.spring4.view.ThymeleafViewResolver(默认使用ThymeleafView作为View)

Thymeleaf提供了SpringTemplateEngine类，用来驱动在Spring MVC下使用Thymeleaf模板引擎，提供了TemplateResolver用来设置通用的模板引擎（包含前后缀）

@Bean

publicTemplateResolver templateResolver(){

TemplateResolver templateResolver=newServletContextTemplateResolver();

templateResolver.setPrefix("/WEB-INF/templates");

templateResolver.setSuffix(".html");

templateResolver.setTemplateMode("HTML5");

returntemplateResolver;

}

@Bean

publicSpringTemplateEngine templateEngine(){

SpringTemplateEngine templateEngine=newSpringTemplateEngine();

templateEngine.setTemplateResolver(templateResolver());

returntemplateEngine;

}

@Bean

publicThymeleafViewResolver thymeleafViewResolver(){

ThymeleafViewResolver thymeleafViewResolver=newThymeleafViewResolver();

thymeleafViewResolver.setTemplateEngine(templateEngine());

returnthymeleafViewResolver;

}

Spring Boot的Thymeleaf支持

Spring Boot通过org.springframework.boot.autoconfigure.thymeleaf包对Thymeleaf进行了自动配置

实战

1.新建Spring Boot项目，选择Thymeleaf依赖

2.javaBean示例

packagecom.hand;

/**

* Created by lqy on 2017-11-26.

public classPerson {

privateString name;

private intage;

publicPerson(){

super();

}

publicPerson(String name,intage){

super();

this.name=name;

this.age=age;

}

publicString getName(){

returnname;

}

public intgetAge(){

returnage;

}

public voidsetName(){

this.name=name;

}

public voidsetAge(){

this.age=age;

}

3.脚本样式静态文件

4.演示页面

代码如下：

<htmlxmlns:th="http://www.thymeleaf.org">

<head>

<metacontent="text/html;charset=UTF-8"/>

<metahttp-equiv="X-UA-Compatible"content="IE=edge"/>

<metaname="viewport"content="width=device-width, initial-scale=1"/>

<linkth:href="@{bootstrap/css/bootstrap.min.css}"rel="stylesheet"/>

<linkth:href="@{bootstrap/css/bootstrap-theme.min.css}"rel="stylesheet"/>

</head>

<body>

<divclass="panel panel-primary">

<divclass="panel-heading">

<h3class="panel-title">访问model</h3>

</div>

<divclass="panel-body">

<spanth:text="${singlePerson.name}"></span>

</div>

<divth:if="${not #lists.isEmpty(people)}">

<divclass="panel panel-primary">

<divclass="panel-heading">

<h3class="panel-title">列表</h3>

</div>

<divclass="panel-body">

<ulclass="list-group">

<liclass="list-group-item"th:each="person:${people}">

<spanth:text="${person.name}"></span>

<spanth:text="${person.age}"></span>

<buttonclass="btn"th:onclick="'getName(\'' + ${person.name} + '\');'">获得名字</button>

</li>

</ul>

</div>

<scriptth:src="@{jquery-1.10.2.min.js}"type="text/javascript"></script>

<scriptth:src="@{bootstrap/js/bootstrap.min.js}"></script>

<scriptth:inline="javascript">

varsingle= [[${singlePerson}]];

console.log(single.name+"/"+single.age)

functiongetName(name){

console.log(name);

}

</script>

</body>

</html>

5.数据准备

做一个控制器

packagecom.hand;

importorg.springframework.stereotype.Controller;

importorg.springframework.ui.Model;

importorg.springframework.web.bind.annotation.RequestMapping;

importjava.util.ArrayList;

importjava.util.List;

/**

* Created by lqy on 2017-11-26.

@Controller

public classPerService {

@RequestMapping("/")

publicString index(Model model){

Person single =newPerson("aa",11);

List<Person> people =newArrayList<Person>();

Person p1 =newPerson("xx",11);

Person p2 =newPerson("yy",22);

Person p3 =newPerson("zz",33);

people.add(p1);

people.add(p2);

people.add(p3);

model.addAttribute("singlePerson", single);

model.addAttribute("people", people);

return"index";

}

入口类

packagecom.hand;

importorg.springframework.boot.SpringApplication;

importorg.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public classSpringThymeleafApplication {

public static voidmain(String[] args) {

SpringApplication.run(SpringThymeleafApplication.class, args);

}

最终访问效果

单击zz可以得到名字

Web相关配置

1.Spring提供的自动配置

1.自动配置的ViewResolver

(1)ContentNegotiatingViewResolver

Spring MVC提供的特殊ViewResolver，ContentNegotiatingViewResolver不是自己处理View，而是代理给不同的ViewResolver来处理不同的View，具备很高的优先级。

(2)BeanNameViewResolver

在控制器（@Controller）中的一个方法返回值的字符串（即视图名）会根据BeanNameViewResolver去查找Bean的名称为返回字符串的View渲染视图。

举例：

定义BeanNameViewResolver的Bean

@Bean

publicBeanNameViewResolver beanNameViewResolver(){

BeanNameViewResolver resolver=newBeanNameViewResolver();

returnresolver;

}

定义一个View的Bean

@Bean

publicMappingJackson2JsonView jsonView(){

MappingJackson2JsonView jsonView=newMappingJackson2JsonView();

returnjsonView;

}

在控制器中返回值字符串为jsonView,它会找Bean名字为jsonView的视图渲染

@RequestMapping(value ="/json",produces ={MediaType.APPLICATION_JSON_VALUE} )

publicString json(Model model){

Person single=newPerson("aa",11);

model.addAttribute("single",single);

return"jsonView";

}

(3)InternalResourceViewResolver

这是极为常用的ViewResolver,主要通过设置前后缀以及控制器中方法返回视图名的字符串，得到实际页面

@Bean

@ConditionalOnMissingBean(InternalResourceViewResolver.class)

publicInternalResourceViewResolver defaultViewResolver(){

InternalResourceViewResolver resolver=newInternalResourceViewResolver();

resolver.setPrefix(this.prefix);

resolver.setSuffix(this.suffix);

returnresolver;

}

2.自动配置的静态资源

在自动配置类的addResourceHandlers方法中定义了以下静态资源的自动配置

(1)类路径文件

把类路径下的/static、/public、/resources和/MEAT-INF/resources文件夹下的静态文件直接映射成/**，通过http://localhost:8080/**直接访问

(2)webjar(将我们脚本框架封装在Jar包中的jar包)

把webjar的/META-INF/resources/webjars/下的静态文件映射为/webjar/**,可以通过http://localhost:8080/webjar/**直接访问

3.自动配置的Formatter和Converter(具体查看WebMvcAutoConfiguration类addFormatters方法)

只要定义了Converter、GenericConverter和Formatter接口的实现类的Bean，这些Bean就自动注册到Spring MVC中

4.自动配置的HttpMessageConverters(具体查看WebMvcAutoConfiguration类)

5.静态首页的支持

把静态index.html文件放置在如下目录：

classpath:/META-INF/resources/index.html

classpath:/resources/index.html

classpath:/static/index.html

classpath:/public/index.html

2.接管Spring Boot的Web配置

如果Spring Boot提供的Spring MVC不满足要求，可以通过定义一个（含有@Configuratioon和@EnableWebMvc注解）配置类来实现完全自己控制的MVC配置。

当需要在Spring Boot提供的基础上额外加自己的配置时，可以定义一个配置类继承WebMvcConfigurerAdapter，无须使用@EnableWebMvc注解。

例如：

@Configuration

public classtestssss extendsWebMvcConfigurerAdapter{

@Override

public voidaddViewControllers(ViewControllerRegistry registry){

registry.addViewController("/xx").setViewName("/xx");

}

提醒：再次重写的addViewControllers方法不会覆盖WebMvcConfigurerAdapter中的方法。我们的配置和Spring Boot自动配置可以同时生效

3.注册Servlet、Filter、Listener

使用嵌入式的Servlet容器（Tomcat、Jetty）时，通过将Servlet、Filter、Listener声明为Spring Bean而达到注册效果。或者注册ServletRegistrationBean、FilterRegistrationBean 和ServletListenerRegistrationBean的Bean

(1)直接注册Bean：

@Bean

publicXxServlet xxServlet(){

return newXxServlet();

}

@Bean

publicYyFilter yyFilter(){

return newYyFilter();

}

@Bean

publicZzListener zzListener(){

return newZzListener();

}

(2)通过RegistrationBean

@Bean

publicServletRegistrationBean servletRegistrationBean(){

return newServletRegistrationBean(newXxServlet(),"/xx/*");

}

@Bean

publicFilterRegistrationBean filterRegistrationBean(){

FilterRegistrationBean registrationBean=newFilterRegistrationBean();

registrationBean.setFilter(newYyFilter());

registrationBean.setOrder(2);

returnregistrationBean;

}

@Bean

publicServletListenerRegistrationBean<ZzListener> zzListenerServletListenerRegistrationBean(){

return newServletListenerRegistrationBean<ZzListener>(newZzListener())

}