對於大多數的Spring初學者來講,一開始接觸的教程都是使用XML進行配置的;通常人天然會有不少不適應,好比一個servlet配置文件名字或者路徑的問題就可能讓你找老半天;其實Servlet從3.0版本起,就能夠不使用web.xml來配置一個應用,Spring 3也提供了相關的支持,stackoverflow上有一個回答: http://stackoverflow.com/questions/15008126/spring-mvc-and-servlets-3-0-do-you-still-need-web-xmljava
示例代碼地址:https://git.oschina.net/issasonjj/SpringNewDemo.gitgit
本文使用的開發工具爲STS(Spring Tool Suite)3.7.1,步驟以下:web
1、工程的新建和配置spring
使用STS新建一個SpringMVC工程,貼上完整的pom.xml:apache
<?xml version="1.0" encoding="utf-8"?> <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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.jxjx</groupId> <artifactId>www</artifactId> <name>SpringNewDemo</name> <packaging>war</packaging> <version>1.0.0-BUILD-SNAPSHOT</version> <properties> <java-version>1.6</java-version> <org.springframework-version>4.2.2.RELEASE</org.springframework-version> <org.aspectj-version>1.6.10</org.aspectj-version> <org.slf4j-version>1.6.6</org.slf4j-version> <apiPath>newdemo</apiPath> </properties> <dependencies> <!-- Spring --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${org.springframework-version}</version> <exclusions> <!-- Exclude Commons Logging in favor of SLF4j --> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${org.springframework-version}</version> </dependency> <!-- AspectJ --> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjrt</artifactId> <version>${org.aspectj-version}</version> </dependency> <!-- Logging --> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>${org.slf4j-version}</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>jcl-over-slf4j</artifactId> <version>${org.slf4j-version}</version> <scope>runtime</scope> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> <version>${org.slf4j-version}</version> <scope>runtime</scope> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.15</version> <exclusions> <exclusion> <groupId>javax.mail</groupId> <artifactId>mail</artifactId> </exclusion> <exclusion> <groupId>javax.jms</groupId> <artifactId>jms</artifactId> </exclusion> <exclusion> <groupId>com.sun.jdmk</groupId> <artifactId>jmxtools</artifactId> </exclusion> <exclusion> <groupId>com.sun.jmx</groupId> <artifactId>jmxri</artifactId> </exclusion> </exclusions> <scope>runtime</scope> </dependency> <!-- jackson --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>2.2.2</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.2.2</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.2.2</version> </dependency> <!-- @Inject --> <dependency> <groupId>javax.inject</groupId> <artifactId>javax.inject</artifactId> <version>1</version> </dependency> <!-- Servlet --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> <!-- Test --> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.7</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <artifactId>maven-eclipse-plugin</artifactId> <version>2.9</version> <configuration> <additionalProjectnatures> <projectnature>org.springframework.ide.eclipse.core.springnature</projectnature> </additionalProjectnatures> <additionalBuildcommands> <buildcommand>org.springframework.ide.eclipse.core.springbuilder</buildcommand> </additionalBuildcommands> <downloadSources>true</downloadSources> <downloadJavadocs>true</downloadJavadocs> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.1</version> <configuration> <source>1.7</source> <target>1.7</target> </configuration> </plugin> <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <version>1.2.1</version> <configuration> <mainClass>org.test.int1.Main</mainClass> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.2</version> <configuration> <failOnMissingWebXml>false</failOnMissingWebXml> </configuration> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <path>/${apiPath}</path> <update>true</update> <url>http://192.168.8.41:8080/manager/text</url> <username>admin</username> <password>admin</password> </configuration> </plugin> </plugins> </build> </project>
請保證javax.servlet-api庫的版本爲3.0及以上,並注意maven-war-plugin插件的failOnMissingWebXml選項,若是沒有設置或者設爲true,沒有web.xml狀況下會編譯出錯。api
刪除WEB-INF文件夾。spring-mvc
2、添加初始化類tomcat
Servlet 3.0後可使用ServletContainerInitializer接口進行初始化而不須要web.xml進行配置;在Spring 3的q實現了此接口,它會調用一個WebApplicationInitializer接口的onStartup方法;所以咱們須要建立一個實現該接口的初始化類;mvc
public class MyAppInitializer implements WebApplicationInitializer { @Override public void onStartup(ServletContext servletContext) throws ServletException { AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext(); context.scan("com.jxjx.www.appconfig"); servletContext.addListener(new ContextLoaderListener(context)); ServletRegistration.Dynamic dispatcher = servletContext.addServlet("DispatcherServlet", new DispatcherServlet(new GenericWebApplicationContext())); dispatcher.setLoadOnStartup(1); dispatcher.addMapping("/*"); } }
熟悉web.xml的讀者能夠發現以上代碼跟XML配置有基本的一一對應關係,故再也不贅述。
app
3、添加配置類
在初始化類的onStartup方法中,有一行代碼context.scan("com.jxjx.www.appconfig"),用於掃描"com.jxjx.www.appconfig"包下的類;咱們就把相關的配置類放在這個包下。
首先建立domain類
public class FooObj { private String name; private String gender; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } }
隨後使用註解進行配置
@Configuration public class DomainConfig { @Bean public FooObj getFooObj() { FooObj obj = new FooObj(); obj.setGender("man"); obj.setName("foo"); return obj; } }
再建立一個控制器配置的類
@Configuration @EnableWebMvc @ComponentScan("com.jxjx.www.spring.controllers") public class WebConfig extends WebMvcConfigurerAdapter { @Override public void configureMessageConverters(final List<HttpMessageConverter<?>> converters) { super.configureMessageConverters(converters); converters.add(new MappingJackson2HttpMessageConverter()); } }
咱們準備提供返回JSON格式數據的接口,因此增長了JSON的Converter。
Controller的內容比較簡單,返回一個JSON便可
@Controller public class HomeController { @Autowired FooObj obj; private static final Logger logger = LoggerFactory.getLogger(HomeController.class); /** * Simply selects the home view to render by returning its name. */ @RequestMapping(value = "/", method = RequestMethod.GET) public @ResponseBody FooObj home(Locale locale, Model model) { logger.info("Welcome home! The client locale is {}.", locale); Date date = new Date(); DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale); String formattedDate = dateFormat.format(date); model.addAttribute("serverTime", formattedDate ); return obj; } }
如此,一個徹底拋棄XML配置的Spring MVC工程就完成了。
總結:拋棄XML其實不是一件難事,大多數的教程仍是因爲慣性而使用大量的XML配置而嚇跑了不少初學者。