spring-mvc 系列：视图（ThymeleafView、InternalResourceView、RedirectView）

一、ThymeleafView
二、转发视图
三、重定向视图
四、视图控制器view-controller
五、配置jsp解析

SpringMVC中的视图是View接口，视图的作用渲染数据，将模型Model中的数据展示给用户

SpringMVC视图的种类很多，默认有转发视图和重定向视图

当工程引入jstl的依赖，转发视图会自动转换为JstlView若使用的视图技术为Thymeleaf，在SpringMVC的配置文件中配置了Thymeleaf的视图解析器，由此视图解析器解析之后所得到的是ThymeleafView

一、ThymeleafView

当控制器方法中所设置的视图名称没有任何前缀时，此时的视图名称会被SpringMVC配置文件中所配置的视图解析器解析，视图名称拼接视图前缀和视图后缀所得到的最终路径，会通过转发的方式实现跳转

html

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<h1>首页</h1>

<a th:href="@{/testThymeleafView}">测试ThymeleafView</a>

</body>

</html>

java

package com.mcode.api.controller;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

/**

 * ClassName: ViewController

 * Package: com.mcode.api.controller

 * Description:

 *

 * @Author: robin

 * @Create: 2023/8/7 - 9:06 PM

 * @Version: v1.0

 */

@Controller

public class ViewController {

    @RequestMapping("/")

    public String index(){

        return "index";

    }

    @RequestMapping("/testThymeleafView")

    public  String testThymeleafView(){

        return "success";

    }

}

DispatcherServlet.render()

AbstractCachingViewResolver.resolveViewName()

ThymeleafViewResolver.createView()

二、转发视图

SpringMVC中默认的转发视图是InternalResourceView

SpringMVC中创建转发视图的情况：

当控制器方法中所设置的视图名称以"forward:"为前缀时，创建InternalResourceView视图，此时的视图名称不会被SpringMVC配置文件中所配置的视图解析器解析，而是会将前缀"forward:"去掉，剩余部分作为最终路径通过转发的方式实现跳转

例如"forward:/"，"forward:/employee"

html

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<h1>首页</h1>

<a th:href="@{/testThymeleafView}">测试ThymeleafView</a>

<a th:href="@{/testForward}">测试InternalResourceView</a>

</body>

</html>

java

package com.mcode.api.controller;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

/**

 * ClassName: ViewController

 * Package: com.mcode.api.controller

 * Description:

 *

 * @Author: robin

 * @Create: 2023/8/7 - 9:06 PM

 * @Version: v1.0

 */

@Controller

public class ViewController {

    @RequestMapping("/")

    public String index(){

        return "index";

    }

    @RequestMapping("/testThymeleafView")

    public  String testThymeleafView(){

        return "success";

    }

    @RequestMapping("/testForward")

    public String testForward(){

        return "forward:/testThymeleafView";

    }

}

三、重定向视图

SpringMVC中默认的重定向视图是RedirectView

当控制器方法中所设置的视图名称以"redirect:"为前缀时，创建RedirectView视图，此时的视图名称不会被SpringMVC配置文件中所配置的视图解析器解析，而是会将前缀"redirect:"去掉，剩余部分作为最终路径通过重定向的方式实现跳转

html

<!DOCTYPE html>

<html lang="en" xmlns:th="http://www.thymeleaf.org">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<h1>首页</h1>

<a th:href="@{/testThymeleafView}">测试ThymeleafView</a>

<a th:href="@{/testForward}">测试InternalResourceView</a>

<a th:href="@{/testRedirect}">测试Redirect</a>

</body>

</html>

java

package com.mcode.api.controller;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

/**

 * ClassName: ViewController

 * Package: com.mcode.api.controller

 * Description:

 *

 * @Author: robin

 * @Create: 2023/8/7 - 9:06 PM

 * @Version: v1.0

 */

@Controller

public class ViewController {

    @RequestMapping("/")

    public String index(){

        return "index";

    }

    @RequestMapping("/testThymeleafView")

    public  String testThymeleafView(){

        return "success";

    }

    @RequestMapping("/testForward")

    public String testForward(){

        return "forward:/testThymeleafView";

    }

    @RequestMapping("/testRedirect")

    public String testRedirect(){

        return "redirect:/testThymeleafView";

    }

}

注：重定向视图在解析时，会先将redirect:前缀去掉，然后会判断剩余部分是否以/开头，若是则会自动拼接上下文路径

四、视图控制器view-controller

当控制器方法中，仅仅用来实现页面跳转，即只需要设置视图名称时，可以将处理器方法使用view-controller标签进行表示

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:context="http://www.springframework.org/schema/context"

       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:component-scan base-package="com.mcode.api.controller"/>

    <!-- 配置Thymeleaf视图解析器 -->

    <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">

        <property name="order" value="1"/>

        <property name="characterEncoding" value="UTF-8"/>

        <property name="templateEngine">

            <bean class="org.thymeleaf.spring5.SpringTemplateEngine">

                <property name="templateResolver">

                    <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">

                        <!-- 视图前缀 -->

                        <property name="prefix" value="/WEB-INF/templates/"/>

                        <!-- 视图后缀 -->

                        <property name="suffix" value=".html"/>

                        <property name="templateMode" value="HTML5"/>

                        <property name="characterEncoding" value="UTF-8"/>

                    </bean>

                </property>

            </bean>

        </property>

    </bean>

    <!--    path：设置处理的请求地址 view-name：设置请求地址所对应的视图名称 -->

    <mvc:view-controller path="/" view-name="index"/>

    <!--  开启mvc注解驱动  -->

    <mvc:annotation-driven/>

</beans>

@Controller

public class ViewController {

//    @RequestMapping("/")

//    public String index(){

//        return "index";

//    }

}

注：当SpringMVC中设置任何一个view-controller时，其他控制器中的请求映射将全部失效，此时需要在SpringMVC的核心配置文件中设置开启mvc注解驱动的标签：<mvc:annotation-driven />

五、配置jsp解析

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:context="http://www.springframework.org/schema/context"

       xmlns:mvc="http://www.springframework.org/schema/mvc"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:component-scan base-package="com.mcode.api.controller"/>

    <!-- 配置Thymeleaf视图解析器 -->

    <bean id="viewResolver" class="org.thymeleaf.spring5.view.ThymeleafViewResolver">

        <property name="order" value="1"/>

        <property name="characterEncoding" value="UTF-8"/>

        <property name="templateEngine">

            <bean class="org.thymeleaf.spring5.SpringTemplateEngine">

                <property name="templateResolver">

                    <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">

                        <!-- 视图前缀 -->

                        <property name="prefix" value="/WEB-INF/templates/"/>

                        <!-- 视图后缀 -->

                        <property name="suffix" value=".html"/>

                        <property name="templateMode" value="HTML5"/>

                        <property name="characterEncoding" value="UTF-8"/>

                    </bean>

                </property>

            </bean>

        </property>

    </bean>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">

        <!--    jsp前缀    -->

        <property name="prefix" value="/jsp/"/>

        <!--     jsp后缀   -->

        <property name="suffix" value=".jsp"/>

        <!--    配置优先等级，越小优先级越高    -->

        <property name="order" value="0"/>

    </bean>

    <!--    path：设置处理的请求地址 view-name：设置请求地址所对应的视图名称 -->

    <mvc:view-controller path="/" view-name="index"/>

    <!--  开启mvc注解驱动  -->

    <mvc:annotation-driven/>

</beans>

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

<h1>首页</h1>

<a href="${pageContext.request.contextPath}/success">success.jsp</a>

</body>

</html>

web.xml

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"

         version="4.0">

注：${pageContext.request.contextPath } 无效大多情况下是由于web.xml版本太低导致的，现在普遍都再用web4.0版本，web-app的版本默认是2.3，而要正确解析上面的代码获得当前路径，我们需要把web-app的版本手动改成2.5及以上版本。

控制器

package com.mcode.api.controller;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

/**

 * ClassName: JSPController

 * Package: com.mcode.api.controller

 * Description:

 *

 * @Author: robin

 * @Create: 2023/8/7 - 10:16 PM

 * @Version: v1.0

 */

@Controller

public class JSPController {

    @RequestMapping("/success")

    public String success(){

        return "success";

    }

}