Spring注解驱动开发(七)-----servlet3.0、springmvc

ServletContainerInitializer

Shared libraries（共享库） / runtimes pluggability（运行时插件能力）

ServletContainerInitializer初始化web容器：

在web容器启动时为提供给第三方组件机会做一些初始化的工作，例如注册servlet或者filters等，servlet规范(JSR356)中通过ServletContainerInitializer实现此功能。

每个框架要使用ServletContainerInitializer就必须在对应的jar包的META-INF/services 目录创建一个名为javax.servlet.ServletContainerInitializer的文件，文件内容指定具体的ServletContainerInitializer实现类，那么，当web容器启动时就会运行这个初始化器做一些组件内的初始化工作。

示例

1、MyServletContainerInitializer

package com.atguigu.servlet;

import java.util.EnumSet;
import java.util.Set;

import javax.servlet.DispatcherType;
import javax.servlet.FilterRegistration;
import javax.servlet.ServletContainerInitializer;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;
import javax.servlet.annotation.HandlesTypes;

import com.atguigu.service.HelloService;

//容器启动的时候会将@HandlesTypes指定的这个类型下面的子类（实现类，子接口等）传递过来；
//传入感兴趣的类型；
@HandlesTypes(value={HelloService.class})
public class MyServletContainerInitializer implements ServletContainerInitializer {

    /**
     * 应用启动的时候，会运行onStartup方法；
     *
     * Set<Class<?>> arg0：感兴趣的类型的所有子类型；
     * ServletContext arg1:代表当前Web应用的ServletContext；一个Web应用一个ServletContext；
     */
    @Override
    public void onStartup(Set<Class<?>> arg0, ServletContext sc) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("感兴趣的类型：");
        for (Class<?> claz : arg0) {
            System.out.println(claz);
        }
    }

}

2、配置

需要新建META-INF/services文件夹，并且文件名为javax.servlet.ServletContainerInitializer，文件内容就为MyServletContainerInitializer的包路径

这样应用启动的时候，会运行onStartup方法，会将所有的HelloService(所有子类或其实现类)拿到。

3、额外添加servlet、filter以及listener组件

修改MyServletContainerInitializer：

package com.atguigu.servlet;

import java.util.EnumSet;
import java.util.Set;

import javax.servlet.DispatcherType;
import javax.servlet.FilterRegistration;
import javax.servlet.ServletContainerInitializer;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;
import javax.servlet.annotation.HandlesTypes;

import com.atguigu.service.HelloService;

//容器启动的时候会将@HandlesTypes指定的这个类型下面的子类（实现类，子接口等）传递过来；
//传入感兴趣的类型；
@HandlesTypes(value={HelloService.class})
public class MyServletContainerInitializer implements ServletContainerInitializer {

    /**
     * 应用启动的时候，会运行onStartup方法；
     *
     * Set<Class<?>> arg0：感兴趣的类型的所有子类型；
     * ServletContext arg1:代表当前Web应用的ServletContext；一个Web应用一个ServletContext；
     *
     * 1）、使用ServletContext注册Web组件（Servlet、Filter、Listener）
     * 2）、使用编码的方式，在项目启动的时候给ServletContext里面添加组件；
     *         必须在项目启动的时候来添加；
     *         1）、ServletContainerInitializer得到的ServletContext；
     *         2）、ServletContextListener得到的ServletContext；
     */
    @Override
    public void onStartup(Set<Class<?>> arg0, ServletContext sc) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("感兴趣的类型：");
        for (Class<?> claz : arg0) {
            System.out.println(claz);
        }

        //注册组件  ServletRegistration
        ServletRegistration.Dynamic servlet = sc.addServlet("userServlet", new UserServlet());
        //配置servlet的映射信息
        servlet.addMapping("/user");

        //注册Listener
        sc.addListener(UserListener.class);

        //注册Filter  FilterRegistration
        FilterRegistration.Dynamic filter = sc.addFilter("userFilter", UserFilter.class);
        //配置Filter的映射信息
        filter.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST), true, "/*");

    }

}

4、UserServlet

package com.atguigu.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class UserServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        resp.getWriter().write("tomcat...");
    }

}

5、UserFilter

package com.atguigu.servlet;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class UserFilter implements Filter {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        // 过滤请求
        System.out.println("UserFilter...doFilter...");
        //放行
        arg2.doFilter(arg0, arg1);

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }

}

6、UserListener

package com.atguigu.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * 监听项目的启动和停止
 * @author lfy
 *
 */
public class UserListener implements ServletContextListener {

    //监听ServletContext销毁
    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        // TODO Auto-generated method stub
        System.out.println("UserListener...contextDestroyed...");
    }

    //监听ServletContext启动初始化
    @Override
    public void contextInitialized(ServletContextEvent arg0) {
        // TODO Auto-generated method stub
        ServletContext servletContext = arg0.getServletContext();
        System.out.println("UserListener...contextInitialized...");
    }

}

Servlet3.0整合springMVC

接入分析

1、web容器在启动的时候，会扫描每个jar包下的META-INF/services/javax.servlet.ServletContainerInitializer
2、加载这个文件指定的类SpringServletContainerInitializer
3、spring的应用一启动会加载感兴趣的WebApplicationInitializer接口的下的所有组件；
4、并且为WebApplicationInitializer组件创建对象（组件不是接口，不是抽象类）
　　1）、AbstractContextLoaderInitializer：创建根容器；createRootApplicationContext()；
　　2）、AbstractDispatcherServletInitializer：
　　　　  创建一个web的ioc容器；createServletApplicationContext();
　　　　  创建了DispatcherServlet；createDispatcherServlet()；
　　　　  将创建的DispatcherServlet添加到ServletContext中；
　　　　　　getServletMappings();
　　3）、AbstractAnnotationConfigDispatcherServletInitializer：注解方式配置的DispatcherServlet初始化器
　　　　  创建根容器：createRootApplicationContext()
　　　　  getRootConfigClasses();传入一个配置类
　　　　  创建web的ioc容器： createServletApplicationContext();
　　　　  获取配置类；getServletConfigClasses();

总结：
以注解方式来启动SpringMVC；继承AbstractAnnotationConfigDispatcherServletInitializer；实现抽象方法指定DispatcherServlet的配置信息；-----通过看源码，得出这个逻辑

===========================
定制SpringMVC；
1）、@EnableWebMvc:开启SpringMVC定制配置功能；
<mvc:annotation-driven/>；

2）、配置组件（视图解析器、视图映射、静态资源映射、拦截器。。。）
extends WebMvcConfigurerAdapter

整合

1、MyWebAppInitializer

package com.atguigu;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import com.atguigu.config.AppConfig;
import com.atguigu.config.RootConfig;

//web容器启动的时候创建对象；调用方法来初始化容器以前前端控制器
public class MyWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    //获取根容器的配置类；（Spring的配置文件）   父容器；
    @Override
    protected Class<?>[] getRootConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?>[]{RootConfig.class};
    }

    //获取web容器的配置类（SpringMVC配置文件）  子容器；
    @Override
    protected Class<?>[] getServletConfigClasses() {
        // TODO Auto-generated method stub
        return new Class<?>[]{AppConfig.class};
    }

    //获取DispatcherServlet的映射信息
    //  /：拦截所有请求（包括静态资源（xx.js,xx.png）），但是不包括*.jsp；
    //  /*：拦截所有请求；连*.jsp页面都拦截；jsp页面是tomcat的jsp引擎解析的；
    @Override
    protected String[] getServletMappings() {
        // TODO Auto-generated method stub
        return new String[]{"/"};
    }

}

2、RootConfig-----spring容器配置类

package com.atguigu.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;

//Spring的容器不扫描controller;父容器
@ComponentScan(value="com.atguigu",excludeFilters={
        @Filter(type=FilterType.ANNOTATION,classes={Controller.class})
})
public class RootConfig {

}

3、AppConfig-----springmvc容器配置类

package com.atguigu.config;

import java.util.List;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.FilterType;
import org.springframework.format.FormatterRegistry;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.stereotype.Controller;
import org.springframework.validation.MessageCodesResolver;
import org.springframework.validation.Validator;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer;
import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.PathMatchConfigurer;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import com.atguigu.controller.MyFirstInterceptor;

//SpringMVC只扫描Controller；子容器
//useDefaultFilters=false 禁用默认的过滤规则；
@ComponentScan(value="com.atguigu",includeFilters={
        @Filter(type=FilterType.ANNOTATION,classes={Controller.class})
},useDefaultFilters=false)
@EnableWebMvc
public class AppConfig  extends WebMvcConfigurerAdapter  {

}

还记得之前在使用xml方式的这些配置吗？

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--将SpringMVC处理不了的请求交给tomcat；静态资源 就可以访问 -->
    <mvc:default-servlet-handler/>
    <!-- SpringMVC的高级功能开启 -->
    <mvc:annotation-driven />

    <!-- <mvc:interceptors>

    </mvc:interceptors>
    <mvc:view-controller path=""/> -->

</beans>

通过注解也可以实现：

定制SpringMVC；
1）、@EnableWebMvc:开启SpringMVC定制配置功能；
<mvc:annotation-driven/>；

2）、配置组件（视图解析器、视图映射、静态资源映射、拦截器。。。）
extends WebMvcConfigurerAdapter

修改AppConfig

package com.atguigu.config;

import java.util.List;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.FilterType;
import org.springframework.format.FormatterRegistry;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.stereotype.Controller;
import org.springframework.validation.MessageCodesResolver;
import org.springframework.validation.Validator;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.config.annotation.AsyncSupportConfigurer;
import org.springframework.web.servlet.config.annotation.ContentNegotiationConfigurer;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.PathMatchConfigurer;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import com.atguigu.controller.MyFirstInterceptor;

//SpringMVC只扫描Controller；子容器
//useDefaultFilters=false 禁用默认的过滤规则；
@ComponentScan(value="com.atguigu",includeFilters={
        @Filter(type=FilterType.ANNOTATION,classes={Controller.class})
},useDefaultFilters=false)
@EnableWebMvc
public class AppConfig  extends WebMvcConfigurerAdapter  {

    //定制

    //视图解析器
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        // TODO Auto-generated method stub
        //默认所有的页面都从 /WEB-INF/ xxx .jsp
        //registry.jsp();
        registry.jsp("/WEB-INF/views/", ".jsp");
    }

    //静态资源访问
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        // TODO Auto-generated method stub
        configurer.enable();//-----相当于<mvc:default-servlet-handler/>，把处理不了的请求交给tomcat
    }

    //拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // TODO Auto-generated method stub
        //super.addInterceptors(registry);
        registry.addInterceptor(new MyFirstInterceptor()).addPathPatterns("/**");
    }

}

MyFirstInterceptor：

package com.atguigu.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class MyFirstInterceptor implements HandlerInterceptor {

    //目标方法运行之前执行
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("preHandle..."+request.getRequestURI());
        return true;
    }

    //目标方法执行正确以后执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("postHandle...");

    }

    //页面响应以后执行
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("afterCompletion...");
    }

}