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Spring MVC学习
Spring MVC 使我们可以简单地,开发灵活且松耦合的Web项目。
在Servlet 2.5及以下,servlet类需要在web.xml文件中,配置<servlet>元素,才能访问这个Servlet。
但在Spring MVC + Servlet 3.0下,通过实现WebApplicationInitializer 接口,便可实现等同web.xml的配置,做到无web.xml。然后可以在WebApplicationInitializer实现类中,通过Spring MVC的 DispatcherServlet配置Servlet。
下面用Maven构建一个,基于注解和Java配置的,无web.xml配置的Spring MVC工程:
1、构建Maven项目,pom.xml文件如下:
<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.qfedu</groupId> <artifactId>SpringMVC</artifactId> <version>1.0</version> <packaging>war</packaging> <properties> <!-- Generic properties --> <java.version>1.8</java.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <!-- build plugins --> <compiler.version>3.6.1</compiler.version> <war.version>3.1.0</war.version> <!-- Web --> <jsp.version>2.2</jsp.version> <jstl.version>1.2</jstl.version> <servlet.version>3.1.0</servlet.version> <!-- Spring --> <spring-framework.version>4.3.9.RELEASE</spring-framework.version> <!-- Logging --> <logback.version>1.2.3</logback.version> <slf4j.version>1.7.25</slf4j.version> </properties> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>${compiler.version}</version> <configuration> <source>${java.version}</source> <target>${java.version}</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>${war.version}</version> <configuration> <failOnMissingWebXml>false</failOnMissingWebXml> </configuration> </plugin> </plugins> </build> <dependencies> <dependency> <groupId>javax</groupId> <artifactId>javaee-web-api</artifactId> <version>7.0</version> <scope>provided</scope> </dependency> <!-- Spring MVC --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring-framework.version}</version> </dependency> <!-- Other web dependency --> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>${jstl.version}</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>${servlet.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>${jsp.version}</version> <scope>provided</scope> </dependency> <!-- Spring and Transactions --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>${spring-framework.version}</version> </dependency> <!-- 使用 SLF4J 和 LogBack 作为日志 --> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>${slf4j.version}</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>jcl-over-slf4j</artifactId> <version>${slf4j.version}</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>${logback.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-core</artifactId> <version>${logback.version}</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-access</artifactId> <version>${logback.version}</version> </dependency> </dependencies> </project>
在Maven的src / main / resources 目录下,新建logback.xml文件,用来配置日志:
<?xml version="1.0" encoding="UTF-8"?> <configuration sacn="true" scanPeriod="1 seconds"> <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator"> <resetJUL>true</resetJUL> </contextListener> <jmxConfiguration /> <appender name="console" class="ch.qos.logback.core.ConsoleAppender"> <encoder> <pattern>logbak: %d{HH:mm:ss.SSS} %logger{36} - %msg%n</pattern> </encoder> </appender> <!-- 将org.springframework.web包下的类的日志级别, 设置为DEBUG, 可以看到Web开发中的, 更详细的错误信息 --> <logger name="org.springframework.web" level="DEBUG" /> <root level="info"> <appender-ref ref="console" /> </root> </configuration>
依然在 src / main / resources 下,建立 views 目录,然后在views目录下,新建 index.jsp页面(内容随意) —— 页面没有放在Maven标准的src /main / webapp / WEB-INF下,这里的目的是,让大家熟悉Spring Boot的页面放置习惯,即放在src / main / resource目录下。(在Eclipse,用模板创建 jsp 页面时,不知道为什么,文件自动被移到了 webapp 目录下,因此如果是这样,需要再移回来)。
Spring MVC 的配置类:
package com.qfedu.springmvc.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.view.InternalResourceViewResolver; import org.springframework.web.servlet.view.JstlView; @Configuration @EnableWebMvc @ComponentScan("com.qfedu.springmvc") public class MyMvcConfig { @Bean public InternalResourceViewResolver viewResolver() { InternalResourceViewResolver viewResolver = new InternalResourceViewResolver(); viewResolver.setPrefix("/WEB-INF/classes/views/"); viewResolver.setSuffix(".jsp"); viewResolver.setViewClass(JstlView.class); return viewResolver; } }
ViewResolver用于映射开发时的路径,与视图的真实位置。因此,对于开发路径 src / main / resource / views,ViewResolver需要将路径前缀配置为 / WEB-INF / classes / views / ,因为运行时页面会自动编译到该目录下。如图:
Web —— Servlet配置:
package com.qfedu.springmvc.config; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRegistration.Dynamic; import org.springframework.web.WebApplicationInitializer; import org.springframework.web.context.support.AnnotationConfigWebApplicationContext; import org.springframework.web.servlet.DispatcherServlet; //实现了WebApplicationInitializer接口, 将会被启动容器的类SpringServletContainerInitializer获取到并完成配置, 就和web.xml一样 public class WebInitializer implements WebApplicationInitializer { @Override public void onStartup(ServletContext servletContext) throws ServletException { //新建WebApplicationContext,并注册配置类(注册配置类中返回的ViewResolver bean),关联当前的ServletContext AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext(); context.register(MyMvcConfig.class); context.setServletContext(servletContext); //DispatcherServlet:前端控制器 //用WebApplicationContext新建Spring MVC的 DispatcherServlet,然后注册并返回Servlet注册对象 Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(context)); //设置DispatcherServlet的Mapping和LoadOnStartUp次序 servlet.addMapping("/"); servlet.setLoadOnStartup(1); } }
一个基本的控制器:
package com.qfedu.springmvc.controller; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; @Controller public class HomeContoller { @RequestMapping("/index") public String index() { return "index"; } }
最后部署到服务器上。
以上步骤即可完成一个比较基本的Spring MVC 项目。
Spring MVC学习