DispatcherServlet是Spring MVC的核心,按照傳統方式, 需要把它配置到web.xml中. 我個人比較不喜歡XML配置方式, XML看起來太累, 冗長繁瑣. 還好借助於Servlet 3規范和Spring 3.1的功能增強, 可以采用一種全新的,更簡潔的方式配置Spring MVC了. 下面按這種方式一個Hello World的MVC配置.
Step 1:先用eclipse創建一個Maven的WEB工程. pom.xml文件如下:
1 <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"> 2 <modelVersion>4.0.0</modelVersion> 3 <groupId>ocr</groupId> 4 <artifactId>ocr</artifactId> 5 <version>0.0.1-SNAPSHOT</version> 6 <packaging>war</packaging> 7 8 <properties> 9 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> 10 <javaee-api.version>7.0</javaee-api.version> 11 <spring.version>4.2.0.RELEASE</spring.version> 12 <junit.version>4.12</junit.version> 13 </properties> 14 15 <dependencies> 16 <dependency> 17 <groupId>javax</groupId> 18 <artifactId>javaee-api</artifactId> 19 <version>${javaee-api.version}</version> 20 </dependency> 21 <dependency> 22 <groupId>junit</groupId> 23 <artifactId>junit</artifactId> 24 <version>${junit.version}</version> 25 </dependency> 26 <dependency> 27 <groupId>org.springframework</groupId> 28 <artifactId>spring-context</artifactId> 29 <version>${spring.version}</version> 30 </dependency> 31 <dependency> 32 <groupId>org.springframework</groupId> 33 <artifactId>spring-aop</artifactId> 34 <version>${spring.version}</version> 35 </dependency> 36 <dependency> 37 <groupId>org.springframework</groupId> 38 <artifactId>spring-webmvc</artifactId> 39 <version>${spring.version}</version> 40 </dependency> 41 <dependency> 42 <groupId>org.springframework</groupId> 43 <artifactId>spring-web</artifactId> 44 <version>${spring.version}</version> 45 </dependency> 46 47 <dependency> 48 <groupId>javax.servlet</groupId> 49 <artifactId>jstl</artifactId> 50 <version>1.2</version> 51 </dependency> 52 53 <dependency> 54 <groupId>commons-logging</groupId> 55 <artifactId>commons-logging</artifactId> 56 <version>1.1.3</version> 57 </dependency> 58 </dependencies> 59 60 61 <build> 62 <plugins> 63 <plugin> 64 <artifactId>maven-compiler-plugin</artifactId> 65 <version>3.3</version> 66 <configuration> 67 <source>1.7</source> 68 <target>1.7</target> 69 </configuration> 70 </plugin> 71 <plugin> 72 <artifactId>maven-war-plugin</artifactId> 73 <version>2.6</version> 74 <configuration> 75 <warSourceDirectory>WebContent</warSourceDirectory> 76 <failOnMissingWebXml>false</failOnMissingWebXml> 77 </configuration> 78 </plugin> 79 </plugins> 80 </build> 81 </project>
Step 2: 配置DispatcherServlet. 需要創建一個Web初始化類OcrWebAppInitializer, 繼承自AbstractAnnotationConfigDispatcherServletInitializer
1 package com.chry.ocr.config; 2 3 import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer; 4 5 public class OcrWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { 6 7 @Override 8 protected Class<?>[] getRootConfigClasses() { 9 return new Class<?>[] { RootConfig.class }; 10 } 11 12 @Override 13 protected Class<?>[] getServletConfigClasses() { 14 return new Class<?>[] { WebConfig.class }; //ָ指定Web配置類 15 } 16 17 @Override 18 protected String[] getServletMappings() { //將DispatcherServlet映射到"/" 19 return new String[] { "/" }; 20 } 21 22 }
Step 3: 配置Spring MVC視圖解析WebConfig.java, 需要要創建一個類繼承自WebMvcConfigurerAdapter
1 package com.chry.ocr.config; 2 3 import org.springframework.context.annotation.Bean; 4 import org.springframework.context.annotation.ComponentScan; 5 import org.springframework.context.annotation.Configuration; 6 import org.springframework.web.servlet.ViewResolver; 7 import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer; 8 import org.springframework.web.servlet.config.annotation.EnableWebMvc; 9 import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter; 10 import org.springframework.web.servlet.view.InternalResourceViewResolver; 11 12 @Configuration 13 @EnableWebMvc //啟動SpringMVC 14 @ComponentScan("com.chry.ocr.controller") //啟動組件掃描 15 public class WebConfig extends WebMvcConfigurerAdapter { 16 17 //配置JSP視圖解析器 18 @Bean 19 public ViewResolver viewResolver() { 20 InternalResourceViewResolver resolver = new InternalResourceViewResolver(); 21 resolver.setPrefix("WEB-INF/views/"); 22 resolver.setSuffix(".jsp"); 23 resolver.setExposeContextBeansAsAttributes(true); 24 return resolver; 25 } 26 27 //配置靜態資源的處理 28 @Override 29 public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) { 30 configurer.enable(); //對靜態資源的請求轉發到容器缺省的servlet,而不使用DispatcherServlet 31 } 32 33 }
Step 4: 配置RootConfig.java
1 package com.chry.ocr.config; 2 3 import org.springframework.context.annotation.ComponentScan; 4 import org.springframework.context.annotation.ComponentScan.Filter; 5 import org.springframework.context.annotation.Configuration; 6 import org.springframework.context.annotation.FilterType; 7 import org.springframework.web.servlet.config.annotation.EnableWebMvc; 8 9 @Configuration 10 @ComponentScan( basePackages={"com.chry.ocr"}, 11 excludeFilters = { @Filter(type=FilterType.ANNOTATION,value=EnableWebMvc.class)} 12 ) 13 14 public class RootConfig { 15 16 }
至此, 傳統方式中需要通過web.xml進行配置的東西就已將全部完成有上面三個java類(OcrWebAppInitializer, RootConfig, WebConfig)完成. 可以開始寫Controller和頁面代碼了
Step 5: 編寫一個HomeController.java, 它將輸出"hello World from Spring MVC"到home.jsp頁面
1 package com.chry.ocr.controller; 2 3 import static org.springframework.web.bind.annotation.RequestMethod.*; 4 import org.springframework.stereotype.Controller; 5 import org.springframework.web.bind.annotation.RequestMapping; 6 import org.springframework.web.bind.annotation.RequestMethod; 7 import org.springframework.web.servlet.ModelAndView; 8 9 @Controller 10 public class HomeController { 11 @RequestMapping(value = "/", method=GET) 12 public ModelAndView home() { 13 String message = "Hello world from Spring MVC"; 14 return new ModelAndView("home", "message", message); 15 } 16 }
Step 6: 編寫一個jsp頁面, 按照我們在視圖解析器和Controller裡面的配置,放在WEB-INF/views/home.jsp中
1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="UTF-8"%> 2 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 3 <html> 4 <head> 5 <title>Spring MVC Tutorial chry</title> 6 <style type="text/css"> 7 </style> 8 </head> 9 <body> 10 <br> 11 <div style='text-align:center;'> 12 ${message} 13 </div> 14 </body>
Step 7: 至此所有工作完成, 使用maven的"clean install"選項進行編譯打包後,在執行,訪問http://localhost:8080即可. 頁面效果和工程結構如下,工程裡面沒有web.xml