springmvc4.x-1(项目搭建)

 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>
		<!-- Generic properties -->
		<java.version>1.7</java.version>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<!-- Web -->
		<jsp.version>2.2</jsp.version>
		<jstl.version>1.2</jstl.version>
		<servlet.version>3.1.0</servlet.version>
		<!-- Spring -->
		<spring-framework.version>4.1.5.RELEASE</spring-framework.version>
		<!-- Logging -->
		<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>

		<!-- Spring MVC -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>${spring-framework.version}</version>
		</dependency>

		<!-- 其他web依赖 -->
		<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>${slf4j.version}</version>
		</dependency>
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.16</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>jcl-over-slf4j</artifactId>
			<version>${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"/> <!-- ① -->
    <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";
    }
}