springmvc4.x-1(项目搭建)

比眉伴天荒 2022-05-16 06:38 256阅读 0赞

`Spring MVC`提供了一个`DispatcherServlet`来开发`Web`应用。在`Servlet2.5`以及以下的时候只要在`web.xml`下配置元素即可。但下面我们采用`Servlet3.0+`无`web.xml`的配置方式，在`Spring ``MVC`里面实现`WebApplicationInitializer`接口便可实现等同于`web.xml`的配置。

### **1. `pom.xml`的内容如下：** ###

<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.wisely</groupId>
    	<artifactId>springmvc4</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>war</packaging>
    
    	<properties>
    		
    		<java.version>1.7</java.version>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    		
    		<jsp.version>2.2</jsp.version>
    		<jstl.version>1.2</jstl.version>
    		<servlet.version>3.1.0</servlet.version>
    		
    		<spring-framework.version>4.1.5.RELEASE</spring-framework.version>
    		
    		<logback.version>1.0.13</logback.version>
    		<slf4j.version>1.7.5</slf4j.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>javax</groupId>
    			<artifactId>javaee-web-api</artifactId>
    			<version>7.0</version>
    			<scope>provided</scope>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-webmvc</artifactId>
    			<version>${spring-framework.version}</version>
    		</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>
    
    		
    		<dependency>
    			<groupId>org.springframework</groupId>
    			<artifactId>spring-tx</artifactId>
    			<version>${spring-framework.version}</version>
    		</dependency>
    
    		
    		<dependency>
    			<groupId>org.slf4j</groupId>
    			<artifactId>slf4j-api</artifactId>
    			<version>${slf4j.version}</version>
    		</dependency>
    		<dependency>
    			<groupId>log4j</groupId>
    			<artifactId>log4j</artifactId>
    			<version>1.2.16</version>
    		</dependency>
    		<dependency>
    			<groupId>org.slf4j</groupId>
    			<artifactId>jcl-over-slf4j</artifactId>
    			<version>${slf4j.version}</version>
    		</dependency>
    		<dependency>
    			<groupId>ch.qos.logback</groupId>
    			<artifactId>logback-classic</artifactId>
    			<version>${logback.version}</version>
    		</dependency>
    		<dependency>
    			<groupId>ch.qos.logback</groupId>
    			<artifactId>logback-core</artifactId>
    			<version>${logback.version}</version>
    		</dependency>
    		<dependency>
    			<groupId>ch.qos.logback</groupId>
    			<artifactId>logback-access</artifactId>
    			<version>${logback.version}</version>
    		</dependency>
    	</dependencies>
    
    	<build>
    		<plugins>
    			<plugin>
    				<groupId>org.apache.maven.plugins</groupId>
    				<artifactId>maven-compiler-plugin</artifactId>
    				<version>2.3.2</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>2.3</version>
    				<configuration>
    					<failOnMissingWebXml>false</failOnMissingWebXml>
    				</configuration>
    			</plugin>
    		</plugins>
    	</build>
    </project>

## 2. 日志配置 ##

在`src/main/resources`目录下，新建`logback.xml`用来配置日志，内容如下：

<?xml version="1.0" encoding="UTF-8"?>
    <configuration scan="true" scanPeriod="1 seconds">
    
        <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
            <resetJUL>true</resetJUL>
        </contextListener>
    
        <jmxConfigurator/>
    
        <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
            <encoder>
                <pattern>logbak: %d{HH:mm:ss.SSS} %logger{36} - %msg%n</pattern>
            </encoder>
        </appender>
    
          <logger name="org.springframework.web" level="DEBUG"/> 
        <root level="info">
            <appender-ref ref="console"/>
        </root>
    </configuration>

## 3. 演示页面 ##

在`src/main/resources`下建立`views`目录，并在此目录下新建`index.jsp`，内容如下：

<%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
        <pre>
            Welcome to Spring MVC world
        </pre>
    </body>
    </html>

## 4. Spring MVC配置 ##

import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.scheduling.annotation.EnableScheduling;
    import org.springframework.web.servlet.config.annotation.EnableWebMvc;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
    import org.springframework.web.servlet.view.InternalResourceViewResolver;
    import org.springframework.web.servlet.view.JstlView;
    
    @Configuration
    @EnableWebMvc// ①
    @ComponentScan("org.light4j.springMvc4")
    public class MyMvcConfig extends WebMvcConfigurerAdapter {// ②
    
        @Bean
        public InternalResourceViewResolver viewResolver() {
            InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
            viewResolver.setPrefix("/WEB-INF/classes/views/");
            viewResolver.setSuffix(".jsp");
            viewResolver.setViewClass(JstlView.class);
            return viewResolver;
        }
    }

这我配置了`JSP`的`ViewResolver`,用来映射路径和实际页面的位置，其中，`@EnableWebMvc`注解会开启一些默认配置，如一些`ViewResolver`或者`MessageConverter`等。

在此处要特别解释一下`Spring ``MVC`的`ViewResolver`，这是`Spring ``MVC`视图(`JSP`下就是`html`)渲染的核心机制;`Spring` `MVC`里有一个接口叫做`ViewResolver`(所有的`ViewResolver`都实现该接口)，实现这个接口要重写方法`resolveViewName()`，这个方法的返回值是接口`View`，而`View`的职责就是使用`model`,`request`,`response`对象，并将渲染的视图(不一定是`html`,可能是`json`,`xml`,`pdf`)返回给浏览器，在以后的文章我会介绍更多关于`ViewResolver`的内容。

## 5. Web配置 ##

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;
    
    public class WebInitializer implements WebApplicationInitializer {// ①
    
        @Override
        public void onStartup(ServletContext servletContext)
                throws ServletException {
            AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
            ctx.register(MyMvcConfig.class);
            ctx.setServletContext(servletContext); // ②
    
            Dynamic servlet = servletContext.addServlet("dispatcher",new DispatcherServlet(ctx)); // ③
            servlet.addMapping("/");
            servlet.setLoadOnStartup(1);
        }
    }

① `WebApplicationInitializer`是`Spring`提供用来配置`Servlet3.0`\+配置的接口，从而实现替代`web.xml`的位置。实现此接口将会自动被`SpringServletContainerInitializer`(用来启动`Servlet3.0`容器)获取到。  
② 新建`WebApplicationContext`，注册配置类，并将其和当前`servletContext`关联。  
③ 注册`Spring ``MVC`的`DispatcherServlet`。

import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    @Controller
    // ①
    public class HelloController {
    
        @RequestMapping("/index")
        // ②
        public String hello() {
    
            return "index";
        }
    }