Spring ModelAndView教程|极客教程

Spring ModelAndView 教程展示了如何在 Spring Web 应用的控制器中使用 ModelAndView。

Spring 是用于创建企业应用的流行 Java 应用框架。

`ModelAndView`

ModelAndView是 Web MVC 框架中Model和View的持有人。这两类是截然不同的。 ModelAndView仅保留两者，以使控制器有可能在单个返回值中返回模型和视图。

该视图由ViewResolver对象解析；该模型是存储在Map中的数据。

Spring `ModelAndView`示例

以下应用使用 ModelAndView 在 Spring 控制器中一步返回模型和视图。我们使用 Freemarker 进行视图解析。

pom.xml
src
├───main
│   ├───java
│   │   └───com
│   │       └───zetcode
│   │           ├───config
│   │           │       MyWebInitializer.java
│   │           │       WebConfig.java
│   │           └───controller
│   │                   MyController.java
│   └───resources
│       │   logback.xml
│       └───templates
│               index.ftl
│               show.ftl
└───test
    └───java

这是项目结构。

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>

    <groupId>com.zetcode</groupId>
    <artifactId>springmodelandview</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <spring-version>5.1.3.RELEASE</spring-version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.freemarker</groupId>
            <artifactId>freemarker</artifactId>
            <version>2.3.28</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.2</version>
            </plugin>

            <plugin>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-maven-plugin</artifactId>
                <version>9.4.14.v20181114</version>
            </plugin>

        </plugins>
    </build>
</project>

在pom.xml中，我们具有必要的依赖性。

resources/logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <logger name="org.springframework" level="ERROR"/>
    <logger name="com.zetcode" level="INFO"/>

    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <Pattern>%d{HH:mm:ss.SSS} %blue(%-5level) %magenta(%logger{36}) - %msg %n
            </Pattern>
        </encoder>
    </appender>

    <root>
        <level value="INFO" />
        <appender-ref ref="consoleAppender" />
    </root>
</configuration>

logback.xml是 Logback 日志库的配置文件。

com/zetcode/config/MyWebInitializer.java

package com.zetcode.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

@Configuration
public class MyWebInitializer extends
        AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {

        return new Class[]{WebConfig.class};
    }

    @Override
    protected String[] getServletMappings() {

        return new String[]{"/"};
    }
}

MyWebInitializer注册 Spring DispatcherServlet，它是 Spring Web 应用的前端控制器。

@Override
protected Class<?>[] getServletConfigClasses() {

    return new Class[]{WebConfig.class};
}

getServletConfigClasses()返回 Web 配置类。

com/zetcode/config/WebConfig.java

package com.zetcode.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = {"com.zetcode"})
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public FreeMarkerViewResolver freemarkerViewResolver() {

        var resolver = new FreeMarkerViewResolver();
        resolver.setCache(true);
        resolver.setSuffix(".ftl");
        return resolver;
    }

    @Bean
    public FreeMarkerConfigurer freemarkerConfig() {

        var freeMarkerConfigurer = new FreeMarkerConfigurer();
        freeMarkerConfigurer.setTemplateLoaderPath("classpath:/templates/");
        return freeMarkerConfigurer;
    }
}

WebConfig配置 FreeMarker 模板引擎。我们将模板文件的位置设置为 classpath 上的templates目录。（resources在类路径上。）

com/zetcode/controller/MyController.java

package com.zetcode.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.servlet.ModelAndView;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

@Controller
public class MyController {

    @GetMapping(value = "/")
    public String home() {

        return "index";
    }

    @GetMapping(value = "/show")
    public ModelAndView show() {

        var mav = new ModelAndView();

        var now = LocalDateTime.now();
        var formatter = DateTimeFormatter.ISO_DATE_TIME;
        var dateTimeFormatted = formatter.format(now);

        mav.addObject("now", dateTimeFormatted);
        mav.setViewName("show");

        return mav;
    }
}

MyController提供了两个 GET 映射。

@GetMapping(value = "/show")
public ModelAndView show() {

show()方法返回ModelAndView。

var mav = new ModelAndView();

var now = LocalDateTime.now();
var formatter = DateTimeFormatter.ISO_DATE_TIME;
var dateTimeFormatted = formatter.format(now);

mav.addObject("now", dateTimeFormatted);
mav.setViewName("show");

return mav;

创建一个ModelAndView并填充数据。数据是格式化的日期时间对象。视图名称由setViewName()设置。 Spring 将视图名称解析为show.ftl。

resources/templates/index.ftl

<!DOCTYPE html>
<html>
    <head>
        <title>Home</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>

        <p>
            <a href="show">Show today's datetime</a>
        </p>

    </body>
</html>

主页包含一个链接，以显示今天的日期时间。

resources/templates/show.ftl

<!DOCTYPE html>
<html>
    <head>
        <title>Today's date</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>

        <p>
            Today is: ${now}
        </p>

    </body>
</html>

在show.ftl视图中，我们使用${}语法显示当前日期时间。