如何用Java類配置Spring MVC(不通過web.xml和XML方式)，mvcweb.xml

如何用Java類配置Spring MVC(不通過web.xml和XML方式)，mvcweb.xml

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. 還好藉助於Servlet 3規範和Spring 3.1的功能增強, 可以採用一種全新的,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建立一個Maven的WEB工程. pom.xml檔案如下:

 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. 需要建立一個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     @Override13     protected Class<?>[] getServletConfigClasses() {14         return new Class<?>[] { WebConfig.class };        //ָ指定Web配置類15     }16 17     @Override18     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, 需要要建立一個類繼承自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 @Configuration13 @EnableWebMvc                                //啟動SpringMVC14 @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     @Bean19     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     @Override29     public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {30         configurer.enable();        //對靜態資源的請求轉寄到容器預設的servlet，而不使用DispatcherServlet31     }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 @Configuration10 @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 @Controller10 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