SpringBoot8-Spring MVC-Spring MVC基本配置

        Spring MVC的定制配置需要我们的配置类继承一个WebMvcConfigurerAdapter类，并在此类使用@EnableWebMvc注解，并开启对Spring MVC的配置支持，这样我们就可以重写这个类的方法，完成我们的常用配置。

        我们将前面的MyMvcConfig配置类继承WebMvcConfigurerAdapter。下面没有特别说明，关于配置的相关内容都在MyMvcConfig里编写。

一：静态资源映射

    程序的静态文件（js，css，图片）等需要直接访问，这时我们可以在配置里重写addResourceHandlers方法来实现。

     示例：

     1，添加静态资源

      我们在src/main/resource建立assets/js目录，并复制一个jquery的js文件放置在此目录，如下：

   配置代码如下：

package jack.springmvc.config;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import org.springframework.web.servlet.view.InternalResourceViewResolver;import org.springframework.web.servlet.view.JstlView;/** * Created by jack on 2017/7/16. */@Configuration@EnableWebMvc   //开启Spring MVC支持，若无此句，重写WebMvcConfigurerAdapter方法无效@ComponentScan("jack.springmvc")//继承WebMvcConfigurerAdapter类，重写其方法可对Spring MVC进行配置public class MyMvcConfig extends WebMvcConfigurerAdapter{    @Bean    public InternalResourceViewResolver viewResolver(){        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();        //viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setSuffix(".jsp");        viewResolver.setViewClass(JstlView.class);        return  viewResolver;    }    @Override    public void addResourceHandlers(ResourceHandlerRegistry registry) {        //super.addResourceHandlers(registry);        //addResourceLocations指的是文件放置的目录，addResourceHandler指的是对外暴露的访问路径        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");    }}

二：拦截器配置

      拦截器（Interceptor）实现对每一个请求前后进行相关的业务处理，类似于Servlet的Filter。

      可让普通的Bean实现HanlderInterceptor接口或者继承HandlerInterceptorAdapter类来实现自定义拦截器。

      通过重写WebMvcConfigurerAdapter的addInterceptors方法来注册自定义拦截器，下面演示一个简单拦截器的开发和配置，业务含义为计算每一次的处理时间。

      示例：

编写拦截器代码：

package jack.springmvc.interceptor;import org.springframework.web.servlet.ModelAndView;import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Created by jack on 2017/7/24. *///继承HandlerInterceptorAdapter类来实现自定义拦截器public class DemoInterceptor extends HandlerInterceptorAdapter{    /**     * 重写preHandle方法，在请求发生之前执行     * @param request     * @param response     * @param handler     * @return     * @throws Exception     */    @Override    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {        //return super.preHandle(request, response, handler);        long startTime = System.currentTimeMillis();        request.setAttribute("startTime",startTime);        return true;    }    /**     * 重写postHandle方法，在请求完成之后执行     * @param request     * @param response     * @param handler     * @param modelAndView     * @throws Exception     */    @Override    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {        //super.postHandle(request, response, handler, modelAndView);        long startTime = (long) request.getAttribute("startTime");        request.removeAttribute("startTime");        long endTime = System.currentTimeMillis();        System.out.println("本次请求处理时间为："+new Long(endTime-startTime)+"ms");        request.setAttribute("handlingTime",endTime-startTime);    }}

配置拦截器，配置拦截器的Bean，重写addInterceptors，注册拦截器，代码如下：

package jack.springmvc.config;import jack.springmvc.interceptor.DemoInterceptor;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import org.springframework.web.servlet.view.InternalResourceViewResolver;import org.springframework.web.servlet.view.JstlView;/** * Created by jack on 2017/7/16. */@Configuration@EnableWebMvc   //开启Spring MVC支持，若无此句，重写WebMvcConfigurerAdapter方法无效@ComponentScan("jack.springmvc")//继承WebMvcConfigurerAdapter类，重写其方法可对Spring MVC进行配置public class MyMvcConfig extends WebMvcConfigurerAdapter{    /**     * 配置拦截器的Bean     * @return     */    @Bean    public DemoInterceptor demoInterceptor(){        return new DemoInterceptor();    }    /**     * c重写addInterceptors方法，注册拦截器     * @param registry     */    @Override    public void addInterceptors(InterceptorRegistry registry) {        //super.addInterceptors(registry);        registry.addInterceptor(demoInterceptor());    }    @Bean    public InternalResourceViewResolver viewResolver(){        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();        //viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setSuffix(".jsp");        viewResolver.setViewClass(JstlView.class);        return  viewResolver;    }    @Override    public void addResourceHandlers(ResourceHandlerRegistry registry) {        //super.addResourceHandlers(registry);        //addResourceLocations指的是文件放置的目录，addResourceHandler指的是对外暴露的访问路径        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");    }}

在浏览器输入：http://localhost:8080/index

输出如下：

三：@ControllerAdvice

      通过@ControllerAdvice，我们可以将对于控制器的全局配置放置在同一个位置，注解了@ControllerAdvice的类的方法可使用@ExceptionHandler，@InitBinder，@ModelAttribute注解到方法上，这对所有注解了@RequestMapping的控制器内的方法有效。

     @ExceptionHandler：用于全局处理控制器的异常

     @InitBinder：用来设置WebDataBinder，WebDataBinder用来自动绑定前台请求参数到Model中。

     @ModelAttribute：@ModelAttribute本来的作用是绑定键值对到Model里，此处是让全局的@RequestMapping都能获得此处设置的键值对。

     下面演示使用@ExceptionHandler处理全局异常，更人性化的将异常输出给用户。

    示例：

1）定制ControllerAdvice

package jack.springmvc.advice;import org.springframework.ui.Model;import org.springframework.web.bind.WebDataBinder;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.InitBinder;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.context.request.WebRequest;import org.springframework.web.servlet.ModelAndView;/** * Created by jack on 2017/7/24. *///@ControllerAdvice声明一个控制器建言，@ControllerAdvice组合了@Component注解，所以自动注册为Spring的bean@ControllerAdvicepublic class ExceptionHandlerAdvice {    /**     * @ExceptionHandler在此处定义全局处理，通过@ExceptionHandler的value属性可过滤拦截的条件，     * 再此我们可以看出我们拦截所有的Exception     * @param exception     * @param request     * @return     */    @ExceptionHandler(value = Exception.class)    public ModelAndView exception(Exception exception, WebRequest request){        ModelAndView modelAndView = new ModelAndView("error");//error页面        modelAndView.addObject("errorMessage",exception.getMessage());        return modelAndView;    }    /**     * 此处使用@ModelAttribute注解将键值对添加到全局，所有注解了@RequestMapping的方法可获得此键值对     * @param model     */    @ModelAttribute    public void addAttributes(Model model){        model.addAttribute("msg", "额外信息");    }    /**     * 通过@InitBinder注解定制WebDataBinder     * @param webDataBinder     */    @InitBinder    public void initBinder(WebDataBinder webDataBinder){        //此处演示忽略request参数的id        webDataBinder.setDisallowedFields("id");    }}

2）演示控制器

package jack.springmvc.controller;import jack.springmvc.domain.DemoObj;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.ModelAttribute;import org.springframework.web.bind.annotation.RequestMapping;/** * Created by jack on 2017/7/24. */@Controllerpublic class AdviceController {    @RequestMapping("/advice")    public String getSomething(@ModelAttribute("msg") String msg, DemoObj obj){        throw new IllegalArgumentException("非常抱歉，参数有误/" + "来自@ModelAttribute：" + msg);    }}

3）异常展示页面

    在src/main/resources/views下，新建error.jsp，内容如下：

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><%@ page contentType="text/html;charset=UTF-8" language="java" pageEncoding="UTF-8" %><html><head>    <meta http-equiv="CONTENT-TYPE" content="text/html; charset=UTF-8" >    <title>@ControllerAdvice Demo</title></head><body><pre>    ${errorMessage}</pre></body></html>

4）运行

 在浏览器输入：http://localhost:8080/advice?id=1&name=xx，页面显示如下所示：

   其中DemoObj的id被过滤掉了。且获得了@ModelAttribute的msg信息

四：其他配置

1，快捷的ViewController

   在前面我们配置页面转向的时候使用了下面的代码：

   @RequestMapping(value = "/index")    public String hello(){        //通过MyMvcConfig里面的配置，通过ViewResolver的Bean配置，返回值为index，        // 说明我们的页面存放的路径为/classes/views/index.jsp        return "index";    }

  此处无任何业务处理，只是简单的页面转向，写了至少三行代码，在实际开发中会涉及大量的这样页面转向，若都这样写会很麻烦，我们可以通过在配置中重写addViewControllers来简化配置：

package jack.springmvc.config;import jack.springmvc.interceptor.DemoInterceptor;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.*;import org.springframework.web.servlet.view.InternalResourceViewResolver;import org.springframework.web.servlet.view.JstlView;/** * Created by jack on 2017/7/16. */@Configuration@EnableWebMvc   //开启Spring MVC支持，若无此句，重写WebMvcConfigurerAdapter方法无效@ComponentScan("jack.springmvc")//继承WebMvcConfigurerAdapter类，重写其方法可对Spring MVC进行配置public class MyMvcConfig extends WebMvcConfigurerAdapter{    /**     * 配置拦截器的Bean     * @return     */    @Bean    public DemoInterceptor demoInterceptor(){        return new DemoInterceptor();    }    /**     * c重写addInterceptors方法，注册拦截器     * @param registry     */    @Override    public void addInterceptors(InterceptorRegistry registry) {        //super.addInterceptors(registry);        registry.addInterceptor(demoInterceptor());    }    @Bean    public InternalResourceViewResolver viewResolver(){        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();        //viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setSuffix(".jsp");        viewResolver.setViewClass(JstlView.class);        return  viewResolver;    }    @Override    public void addResourceHandlers(ResourceHandlerRegistry registry) {        //super.addResourceHandlers(registry);        //addResourceLocations指的是文件放置的目录，addResourceHandler指的是对外暴露的访问路径        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");    }    /**     * 统一处理没啥业务逻辑处理的controller请求，实现代码的简洁     * @param registry     */    @Override    public void addViewControllers(ViewControllerRegistry registry) {        //super.addViewControllers(registry);        registry.addViewController("/index").setViewName("/index");    }}

注释掉之前处理/index的controller，重启服务器，输入http://localhost:8080/index进行访问，发现和之前是一样的结果。把没有业务的controller统一进行处理，代码根据简洁，管理更加集中了。

2，路径匹配参数配置

       在spring mvc中，路径参数如果带“.”的话，“.”后面的值将被忽略，例如访问：http://localhost:8080/anno/pathvar/xx.yy,此时“.”后面的yy被忽略了，如下所示：

通过重写configurePathMatch方法可忽略"."后面的参数，代码如下：

@Override    public void configurePathMatch(PathMatchConfigurer configurer) {        //super.configurePathMatch(configurer);        configurer.setUseSuffixPatternMatch(false);    }

目前spring mvc配置的完整代码如下：

package jack.springmvc.config;import jack.springmvc.interceptor.DemoInterceptor;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.*;import org.springframework.web.servlet.view.InternalResourceViewResolver;import org.springframework.web.servlet.view.JstlView;/** * Created by jack on 2017/7/16. */@Configuration@EnableWebMvc   //开启Spring MVC支持，若无此句，重写WebMvcConfigurerAdapter方法无效@ComponentScan("jack.springmvc")//继承WebMvcConfigurerAdapter类，重写其方法可对Spring MVC进行配置public class MyMvcConfig extends WebMvcConfigurerAdapter{    /**     * 配置拦截器的Bean     * @return     */    @Bean    public DemoInterceptor demoInterceptor(){        return new DemoInterceptor();    }    /**     * c重写addInterceptors方法，注册拦截器     * @param registry     */    @Override    public void addInterceptors(InterceptorRegistry registry) {        //super.addInterceptors(registry);        registry.addInterceptor(demoInterceptor());    }    @Bean    public InternalResourceViewResolver viewResolver(){        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();        //viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setPrefix("/WEB-INF/classes/views/");        viewResolver.setSuffix(".jsp");        viewResolver.setViewClass(JstlView.class);        return  viewResolver;    }    @Override    public void addResourceHandlers(ResourceHandlerRegistry registry) {        //super.addResourceHandlers(registry);        //addResourceLocations指的是文件放置的目录，addResourceHandler指的是对外暴露的访问路径        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");    }    /**     * 统一处理没啥业务逻辑处理的controller请求，实现代码的简洁     * @param registry     */    @Override    public void addViewControllers(ViewControllerRegistry registry) {        //super.addViewControllers(registry);        registry.addViewController("/index").setViewName("/index");    }    @Override    public void configurePathMatch(PathMatchConfigurer configurer) {        //super.configurePathMatch(configurer);        configurer.setUseSuffixPatternMatch(false);    }}

重启tomcat，在访问http://localhost:8080/anno/pathvar/xx.yy，就可以接受"."后面的yy了，如下：

3，更多配置

    更多配置可以查看WebMvcConfigurerAdapter类的api。因其是WebMvcConfigurer接口的实现，所以WebMvcConfigurer的api内的也可以用来MVC。下面看看WebMvcConfigurerAdapter和WebMvcConfigurer的源码。

WebMvcConfigurerAdapter：

//// Source code recreated from a .class file by IntelliJ IDEA// (powered by Fernflower decompiler)//package org.springframework.web.servlet.config.annotation;import java.util.List;import org.springframework.format.FormatterRegistry;import org.springframework.http.converter.HttpMessageConverter;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.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;public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {    public WebMvcConfigurerAdapter() {    }    public void configurePathMatch(PathMatchConfigurer configurer) {    }    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {    }    public void configureAsyncSupport(AsyncSupportConfigurer configurer) {    }    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {    }    public void addFormatters(FormatterRegistry registry) {    }    public void addInterceptors(InterceptorRegistry registry) {    }    public void addResourceHandlers(ResourceHandlerRegistry registry) {    }    public void addCorsMappings(CorsRegistry registry) {    }    public void addViewControllers(ViewControllerRegistry registry) {    }    public void configureViewResolvers(ViewResolverRegistry registry) {    }    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {    }    public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {    }    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {    }    public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {    }    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {    }    public void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> exceptionResolvers) {    }    public Validator getValidator() {        return null;    }    public MessageCodesResolver getMessageCodesResolver() {        return null;    }}

WebMvcConfigurer：

//// Source code recreated from a .class file by IntelliJ IDEA// (powered by Fernflower decompiler)//package org.springframework.web.servlet.config.annotation;import java.util.List;import org.springframework.format.FormatterRegistry;import org.springframework.http.converter.HttpMessageConverter;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.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;public interface WebMvcConfigurer {    void configurePathMatch(PathMatchConfigurer var1);    void configureContentNegotiation(ContentNegotiationConfigurer var1);    void configureAsyncSupport(AsyncSupportConfigurer var1);    void configureDefaultServletHandling(DefaultServletHandlerConfigurer var1);    void addFormatters(FormatterRegistry var1);    void addInterceptors(InterceptorRegistry var1);    void addResourceHandlers(ResourceHandlerRegistry var1);    void addCorsMappings(CorsRegistry var1);    void addViewControllers(ViewControllerRegistry var1);    void configureViewResolvers(ViewResolverRegistry var1);    void addArgumentResolvers(List<HandlerMethodArgumentResolver> var1);    void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> var1);    void configureMessageConverters(List<HttpMessageConverter<?>> var1);    void extendMessageConverters(List<HttpMessageConverter<?>> var1);    void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> var1);    void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> var1);    Validator getValidator();    MessageCodesResolver getMessageCodesResolver();}