WebMvcConfigurer这个接口干什么用，文字上的描述我就不再说了，我们直接从功能入手就知道这玩意能帮我们做些什么事
首先我们打开这个接口所定义的哪些方法
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public
interface WebMvcConfigurer {
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default void configurePathMatch(PathMatchConfigurer configurer) {}
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default void configureContentNegotiation(ContentNegotiationConfigurer configurer) {}
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default void configureAsyncSupport(AsyncSupportConfigurer configurer) {}
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default void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {}
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default void addFormatters(FormatterRegistry registry) {}
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default void addInterceptors(InterceptorRegistry registry) {}
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default void addResourceHandlers(ResourceHandlerRegistry registry) {}
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default void addCorsMappings(CorsRegistry registry) {}
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default void addViewControllers(ViewControllerRegistry registry) {}
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default void configureViewResolvers(ViewResolverRegistry registry) {}
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default void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {}
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default void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> handlers) {}
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default void configureMessageConverters(List<HttpMessageConverter<?>> converters) {}
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default void extendMessageConverters(List<HttpMessageConverter<?>> converters) {}
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default void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {}
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default void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {}
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@Nullable
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default Validator getValidator() {
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return
null;
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}
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@Nullable
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default MessageCodesResolver getMessageCodesResolver() {
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return
null;
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}
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}
这里面吧定义了N多个方法供我们自定义添加配置，其中这里我就挑几个比较常用的来示范下它的用途
一、addInterceptors
从名字上看我们就可以猜到是添加自定义拦截器的，下面来示范下
1.定义HandlerInterceptor
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public
class MyInterceptor implements HandlerInterceptor{
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@Override
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public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
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System.out.println(
"preHandle:假设这里请求前进行判断是否有登陆");
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//假设这里请求前进行判断是否有登陆,有则return true，无则false
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return
true;
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}
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@Override
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public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
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//请求中处理，也就是HandlerAdapter处理Handler后在返回视图前执行该方法
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System.out.println(
"postHandle==requestUrl:"+request.getRequestURI());
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}
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@Override
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public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
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//提交视图后执行该方法
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System.out.println(
"afterCompletion==requestUrl:"+request.getRequestURI());
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}
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}
2.定义WebMvcConfigurer添加addInterceptors
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@Configuration
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public
class MyWebMvcConfigurer implements WebMvcConfigurer {
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@Override
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public void addInterceptors(InterceptorRegistry registry) {
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registry.addInterceptor(
new MyInterceptor()).addPathPatterns(
"/**").excludePathPatterns(
"/user/login");
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}
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}
.addPathPatterns("/**")表示拦截所有请求；.excludePathPatterns("/user/login")表示不拦截该请求
3.定义controller
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@RestController
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@RequestMapping(
"/user")
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public
class UserController {
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@RequestMapping(
"/login")
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public String index() {
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return
"hello springmvc!login";
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}
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@RequestMapping(
"/get")
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public String get(){
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return
"hello springmvc!get";
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}
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}
4.执行结果
1）调用login方法：
因为是login故这里是不会进拦截，所以就不会打印任何东西
2）请求get方法：
这里进了拦截器所以会进行打印操作
二、addArgumentResolvers
从方法参数上可以猜测到添加自定义HandlerMethodArgumentResolver参数解析，下面我们来操作看下
1.定义HandlerMethodArgumentResolver：
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class MyHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {
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@Override
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public boolean supportsParameter(MethodParameter parameter) {
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return parameter.getParameterType().getName().equals(UserA.class.getName());
//仅对UserA有效
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}
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@Override
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public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
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//模拟从session中获取登陆的用户信息
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Object attribute = webRequest.getAttribute(
"user", NativeWebRequest.SCOPE_SESSION);
//Request中的用户属性
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//然后放入UserA的对象里
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//这里直接写死一个
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attribute =
new UserA(
"sessionUserName",
20);
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return attribute;
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}
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}
2.定义WebMvcConfigurer添加addArgumentResolvers：
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@Override
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public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
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resolvers.add(
new MyHandlerMethodArgumentResolver());
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}
3.定义controller：
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@RequestMapping(
"/index")
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public String index(UserA userA){
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return
"hello springmvc!userA:"+userA;
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}
4.执行结果：
这里能看取到在resolveArgument赋值的userA
三、addResourceHandlers
静态资源访问
1.我们直接重写addResourceHandlers方法：
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@Configuration
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public
class MyWebMvcConfigurer implements WebMvcConfigurer {
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@Override
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public void addResourceHandlers(ResourceHandlerRegistry registry) {
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registry.addResourceHandler(
"/file/**").addResourceLocations(
"classpath:/static/",
"file:D:/tomcat/");
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}
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}
addResourceHandler("/file/**")添加对外访问路径，addResourceLocations添加本地目录资源路径
2.本地资源：
3.访问资源:
ok.其他的方法我就不再尝试了，网上资料一大堆，主要这里是记录下有这么个配置类叫做WebMvcConfigurer，他非常好用
转载：https://blog.csdn.net/u011320740/article/details/105495831
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