中央转发器（DispatcherServlet）

控制器

视图解析器

静态资源访问

消息转换器

格式化

静态资源管理

一、中央转发器

Xml无需配置

<servlet>
    <servlet-name>chapter2</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>chapter2</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

中央转发器被springboot自动接管，不再需要我们在web.xml中配置，我们现在的项目也不是web项目，也不存在web.xml,

org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,

控制器

控制器Controller在springboot的注解扫描范围内自动管理。

视图解析器自动管理

Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.

ContentNegotiatingViewResolver：组合所有的视图解析器的；

曾经的配置文件无需再配

<bean id="de" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"></property>
<property name="suffix" value="*.jsp"></property>
</bean>

源码：

public ContentNegotiatingViewResolver viewResolver(BeanFactory beanFactory) {
ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
resolver.setContentNegotiationManager((ContentNegotiationManager)beanFactory.getBean(ContentNegotiationManager.class));
resolver.setOrder(-2147483648);
return resolver;
}

当我们做文件上传的时候我们也会发现multipartResolver是自动被配置好的页面

<form action="/upload" method="post" enctype="multipart/form-data">
<input name="pic" type="file">
<input type="submit">
</form>

Controller

@ResponseBody
@RequestMapping("/upload")
public String upload(@RequestParam("pic")MultipartFile file, HttpServletRequest request){
String contentType = file.getContentType();
String fileName = file.getOriginalFilename();
/*System.out.println("fileName-->" + fileName);
System.out.println("getContentType-->" + contentType);*/
//String filePath = request.getSession().getServletContext().getRealPath("imgupload/");
String filePath = "D:/imgup/";
try {
this.uploadFile(file.getBytes(), filePath, fileName);
} catch (Exception e) {
// TODO: handle exception
}

return "success";
}

public static void uploadFile(byte[] file, String filePath, String fileName) throws Exception {
File targetFile = new File(filePath);
if(!targetFile.exists()){
targetFile.mkdirs();
}
FileOutputStream out = new FileOutputStream(filePath+fileName);
out.write(file);
out.flush();
out.close();
}

文件上传大小可以通过配置来修改

打开application.properties, 默认限制是10MB，我们可以任意修改

文件上传大小可以通过配置来修改

打开application.properties, 默认限制是10MB，我们可以任意修改

二、消息转换和格式化

Springboot自动配置了消息转换器

格式化转换器的自动注册

时间类型我们可以在这里修改

在配置文件中指定好时间的模式我们就可以输入了

三、springboot自动扩展SpringMVC

在实际开发中springboot并非完全自动化，很多跟业务相关我们需要自己扩展，springboot给我提供了接口。

我们可以来通过实现WebMvcConfigurer接口来扩展

public interface WebMvcConfigurer {
default void configurePathMatch(PathMatchConfigurer configurer) {
}

default void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
}

default void configureAsyncSupport(AsyncSupportConfigurer configurer) {
}

default void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
}

default void addFormatters(FormatterRegistry registry) {
}

default void addInterceptors(InterceptorRegistry registry) {
}

default void addResourceHandlers(ResourceHandlerRegistry registry) {
}

default void addCorsMappings(CorsRegistry registry) {
}

default void addViewControllers(ViewControllerRegistry registry) {
}

default void configureViewResolvers(ViewResolverRegistry registry) {
}

default void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
}

default void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> handlers) {
}

default void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
}

default void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
}

default void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
}

default void extendHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
}

@Nullable
default Validator getValidator() {
return null;
}

@Nullable
default MessageCodesResolver getMessageCodesResolver() {
return null;
}
}

3.1 在容器中注册视图控制器（请求转发）

创建一个MyMVCCofnig实现WebMvcConfigurer接口，实现一下addViewControllers方法，我们完成通过/tx访问，转发到success.html的工作

@Configuration
public class MyMVCCofnig implements WebMvcConfigurer{
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/tx").setViewName("success");
}

}

3.2 注册格式化

用来可以对请求过来的日期格式化的字符串来做定制化。当然通过application.properties配置也可以办到。

@Override
public void addFormatters(FormatterRegistry registry) {
registry.addFormatter(new Formatter<Date>() {
@Override
public String print(Date date, Locale locale) {
return null;
}
@Override
public Date parse(String s, Locale locale) throws ParseException {
return new SimpleDateFormat("yyyy-MM-dd").parse(s);
}
});
}

3.3 消息转换器扩展fastjson

在pom.xml中引入fastjson

<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>fastjson</artifactId>
   <version>1.2.47</version>
</dependency>

配置消息转换器，添加fastjson

@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
FastJsonHttpMessageConverter fc = new FastJsonHttpMessageConverter();
FastJsonConfig fastJsonConfig = new FastJsonConfig();
fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
fc.setFastJsonConfig(fastJsonConfig);
converters.add(fc);
}

在实体类上可以继续控制

public class User{private  String username;private  String password;private int age;private int score;private int gender;@JSONField(format = "yyyy-MM-dd")private Date date;

3.4 拦截器注册

1.创建拦截器

public class MyInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("前置拦截");
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("后置拦截");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("最终拦截");
}
}

2. 拦截器注册

@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new MyInterceptor())
.addPathPatterns("/**")
.excludePathPatterns("/hello2");
}