不使用XML配置SpringMVC

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。

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