Spring Web工程web.xml零配置即便用Java Config + Annotation

時間 2019-11-12

標籤 spring web 工程 web.xml xml 配置即便 java config annotation 欄目 Spring 简体版

原文原文鏈接

摘要: 在Spring 3.0以前，咱們工程中經常使用Bean都是經過XML形式的文件註解的，少了還能夠，可是數量多，關係複雜到後期就很難維護了，因此在3.x以後Spring官方推薦使用Java Config方式去替換之前冗餘的XML格式文件的配置方式；

java

在開始以前，咱們須要注意一下，要基於Java Config實現無web.xml的配置，咱們的工程的Servlet必須是3.0及其以上的版本；web

一、咱們要實現無web.xml的配置，只須要關注實現WebApplicationInitializer這個接口，如下爲Spring源碼：spring

public interface WebApplicationInitializer {

    /**
     * Configure the given {@link ServletContext} with any servlets, filters, listeners
     * context-params and attributes necessary for initializing this web application. See
     * examples {@linkplain WebApplicationInitializer above}.
     * @param servletContext the {@code ServletContext} to initialize
     * @throws ServletException if any call against the given {@code ServletContext}
     * throws a {@code ServletException}
     */
    void onStartup(ServletContext servletContext) throws ServletException;

}

二、咱們這裏先不講他的原理，只要咱們工程中實現這個接口的類，Spring容器在啓動時候就會監聽到咱們所實現的這個類，從而讀取咱們的配置，就如讀取web.xml同樣，咱們的實現類以下所示：mvc

public class WebProjectConfigInitializer implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext container) {

        initializeSpringConfig(container);

        initializeLog4jConfig(container);

        initializeSpringMVCConfig(container);

        registerServlet(container);

        registerListener(container);

        registerFilter(container);
    }

    private void initializeSpringConfig(ServletContext container) {
        // Create the 'root' Spring application context
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.register(AppConfiguration.class);
        // Manage the life cycle of the root application context
        container.addListener(new ContextLoaderListener(rootContext));
    }

    private void initializeSpringMVCConfig(ServletContext container) {
        // Create the spring rest servlet's Spring application context
        AnnotationConfigWebApplicationContext dispatcherContext = new AnnotationConfigWebApplicationContext();
        dispatcherContext.register(RestServiceConfiguration.class);

        // Register and map the spring rest servlet
        ServletRegistration.Dynamic dispatcher = container.addServlet("SpringMvc",
                new DispatcherServlet(dispatcherContext));
        dispatcher.setLoadOnStartup(2);
        dispatcher.setAsyncSupported(true);
        dispatcher.addMapping("/springmvc/*");
    }

    private void initializeLog4jConfig(ServletContext container) {
        // Log4jConfigListener
        container.setInitParameter("log4jConfigLocation", "file:${rdm.home}/log4j.properties");
        container.addListener(Log4jConfigListener.class);
        PropertyConfigurator.configureAndWatch(System.getProperty("rdm.home") + "/log4j.properties", 60);
    }

    private void registerServlet(ServletContext container) {

        initializeStaggingServlet(container);
    }

    private void registerFilter(ServletContext container) {
        initializeSAMLFilter(container);
    }

    private void registerListener(ServletContext container) {
        container.addListener(RequestContextListener.class);
    }

    private void initializeSAMLFilter(ServletContext container) {
        FilterRegistration.Dynamic filterRegistration = container.addFilter("SAMLFilter", DelegatingFilterProxy.class);
        filterRegistration.addMappingForUrlPatterns(null, false, "/*");
        filterRegistration.setAsyncSupported(true);
    }

    private void initializeStaggingServlet(ServletContext container) {
        StaggingServlet staggingServlet = new StaggingServlet();
        ServletRegistration.Dynamic dynamic = container.addServlet("staggingServlet", staggingServlet);
        dynamic.setLoadOnStartup(3);
        dynamic.addMapping("*.stagging");
    }
}

三、以上的Java Config等同於以下web.xml配置：app

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </param-value>
    </context-param>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>com.g360.configuration.AppConfiguration</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
     <context-param> 
        <param-name>log4jConfigLocation</param-name> 
        <param-value>file:${rdm.home}/log4j.properties</param-value> 
    </context-param> 
     <listener> 
        <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> 
    </listener> 

    <servlet>
        <description>staggingServlet</description>
        <display-name>staggingServlet</display-name>
        <servlet-name>staggingServlet</servlet-name>
        <servlet-class>com.g360.bean.interfaces.StaggingServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>staggingServlet</servlet-name>
        <url-pattern>*.stagging</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>SpringMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextClass</param-name>
            <param-value>
                org.springframework.web.context.support.AnnotationConfigWebApplicationContext
            </param-value>
        </init-param>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>com.g360.configuration.RestServiceConfiguration</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>
    <servlet-mapping>
        <servlet-name>SpringMvc</servlet-name>
        <url-pattern>/springmvc/*</url-pattern>
    </servlet-mapping>
    <filter> 
        <filter-name>SAMLFilter</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
        <async-supported>true</async-supported>
     </filter> 
    <filter-mapping> 
    <filter-name>SAMLFilter</filter-name> 
        <url-pattern>/*</url-pattern> 
    </filter-mapping> 
    <listener>
        <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
    </listener>

    <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
    </welcome-file-list>
</web-app>

四、咱們分類解讀，在web.xml配置裏面咱們配置的Web Application Contextless

    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </param-value>
    </context-param>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>com.g360.configuration.AppConfiguration</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

就等價於Java Config中的jsp

private void initializeSpringConfig(ServletContext container) {
        // Create the 'root' Spring application context
        AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
        rootContext.register(AppConfiguration.class);
        // Manage the life cycle of the root application context
        container.addListener(new ContextLoaderListener(rootContext));
}

如此推斷，在web.xml配置裏面咱們配置的log4jasync

<context-param> 
        <param-name>log4jConfigLocation</param-name> 
        <param-value>file:${rdm.home}/log4j.properties</param-value> 
</context-param> 
<listener> 
        <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> 
</listener>

就等價於Java Config的ide

    private void initializeLog4jConfig(ServletContext container) {
        // Log4jConfigListener
        container.setInitParameter("log4jConfigLocation", "file:${rdm.home}/log4j.properties");
        container.addListener(Log4jConfigListener.class);
        PropertyConfigurator.configureAndWatch(System.getProperty("rdm.home") + "/log4j.properties", 60);
    }

類此，在web.xml配置裏面咱們配置的Spring Web(Spring Restful)this

    <servlet>
        <servlet-name>SpringMvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextClass</param-name>
            <param-value>
                org.springframework.web.context.support.AnnotationConfigWebApplicationContext
            </param-value>
        </init-param>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>com.g360.configuration.RestServiceConfiguration</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>
    <servlet-mapping>
        <servlet-name>SpringMvc</servlet-name>
        <url-pattern>/springmvc/*</url-pattern>
    </servlet-mapping>

就等價於Java Config中的

private void initializeSpringMVCConfig(ServletContext container) {
        // Create the spring rest servlet's Spring application context
        AnnotationConfigWebApplicationContext dispatcherContext = new AnnotationConfigWebApplicationContext();
        dispatcherContext.register(RestServiceConfiguration.class);

        // Register and map the spring rest servlet
        ServletRegistration.Dynamic dispatcher = container.addServlet("SpringMvc",
                new DispatcherServlet(dispatcherContext));
        dispatcher.setLoadOnStartup(2);
        dispatcher.setAsyncSupported(true);
        dispatcher.addMapping("/springmvc/*");
}

再此，在web.xml配置裏面咱們配置的servlet

    <servlet>
        <description>staggingServlet</description>
        <display-name>staggingServlet</display-name>
        <servlet-name>staggingServlet</servlet-name>
        <servlet-class>com.g360.bean.interfaces.StaggingServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>staggingServlet</servlet-name>
        <url-pattern>*.stagging</url-pattern>
    </servlet-mapping>

就等價於Java Config中的

    private void initializeStaggingServlet(ServletContext container) {
        StaggingServlet staggingServlet = new StaggingServlet();
        ServletRegistration.Dynamic dynamic = container.addServlet("staggingServlet", staggingServlet);
        dynamic.setLoadOnStartup(3);
        dynamic.addMapping("*.stagging");
    }

後面以此類推，在這裏不加詳述了；

五、如上面所說的，咱們對Web 工程的總體配置都依賴於AppConfiguration這個配置類，下面是使用@Configuration 配置類註解的，你們使用過的，以此類推，都比較清楚，

這裏就不加贅述了；

@Configuration
@EnableTransactionManagement
@EnableAsync
@EnableAspectJAutoProxy
@EnableScheduling
@Import({ RestServiceConfiguration.class, BatchConfiguration.class, DatabaseConfiguration.class, ScheduleConfiguration.class})
@ComponentScan({ "com.service", "com.dao", "com.other"})
public class AppConfiguration
{

  private Logger logger = LoggerFactory.getLogger(AppConfiguration.class);

  /**
   * 
   */
  public AppConfiguration ()
  {
    // TODO Auto-generated constructor stub
    logger.info("[Initialize application]");
    Locale.setDefault(Locale.US);
  }

}

還有就是對Spring Web配置的類RestServiceConfiguration ，我的可根據本身的實際項目需求在此配置本身的視圖類型以及類型轉換等等

@Configuration
@EnableWebMvc
@EnableAspectJAutoProxy(proxyTargetClass = true)
@ComponentScan(basePackages = { "com.bean" })
public class RestServiceConfiguration extends WebMvcConfigurationSupport {
    
    @Bean
    public RequestMappingHandlerAdapter requestMappingHandlerAdapter() {
        RequestMappingHandlerAdapter handlerAdapter = super.requestMappingHandlerAdapter();
        return handlerAdapter;
    }

    @Bean
    public LocaleChangeInterceptor localeChangeInterceptor() {
        return new LocaleChangeInterceptor();
    }

    @Bean
    public LogAspect logAspect() {
        return new LogAspect();
    }
}