4. SpringMVC自动配置
https://docs.spring.io/spring-boot/docs/1.5.10.RELEASE/reference/htmlsingle/#boot-features-developing-web-applications
1. Spring MVC auto-configuration
Spring Boot 自动配置好了SpringMVC
以下是SpringBoot对SpringMVC的默认配置:==(WebMvcAutoConfiguration)==
-
Inclusion of
ContentNegotiatingViewResolver
andBeanNameViewResolver
beans.- 自动配置了ViewResolver(视图解析器:根据方法的返回值得到视图对象(View),视图对象决定如何渲染(转发?重定向?))
- ContentNegotiatingViewResolver:组合所有的视图解析器的;
- ==如何定制:我们可以自己给容器中添加一个视图解析器;自动的将其组合进来;==
Support for serving static resources, including support for WebJars (see below).静态资源文件夹路径,webjars
Static
index.html
support. 静态首页访问Custom
Favicon
support (see below). favicon.ico-
自动注册了 of
Converter
,GenericConverter
,Formatter
beans.- Converter:转换器; public String hello(User user):类型转换使用Converter
-
Formatter
格式化器; 2017.12.17===Date;
@Bean
@ConditionalOnProperty(prefix = "spring.mvc", name = "date-format")//在文件中配置日期格式化的规则
public Formatter dateFormatter() {
return new DateFormatter(this.mvcProperties.getDateFormat());//日期格式化组件
}
==自己添加的格式化器转换器,我们只需要放在容器中即可==
-
Support for
HttpMessageConverters
(see below).HttpMessageConverter:SpringMVC用来转换Http请求和响应的;User---Json;
-
HttpMessageConverters
是从容器中确定;获取所有的HttpMessageConverter;==自己给容器中添加HttpMessageConverter,只需要将自己的组件注册容器中(@Bean,@Component)==
Automatic registration of
MessageCodesResolver
(see below).定义错误代码生成规则-
Automatic use of a
ConfigurableWebBindingInitializer
bean (see below).==我们可以配置一个ConfigurableWebBindingInitializer来替换默认的;(添加到容器)==
初始化WebDataBinder; 请求数据=====JavaBean;
org.springframework.boot.autoconfigure.web:web的所有自动场景;
If you want to keep Spring Boot MVC features, and you just want to add additional MVC configuration (interceptors, formatters, view controllers etc.) you can add your own @Configuration
class of type WebMvcConfigurerAdapter
, but without @EnableWebMvc
. If you wish to provide custom instances of RequestMappingHandlerMapping
, RequestMappingHandlerAdapter
or ExceptionHandlerExceptionResolver
you can declare a WebMvcRegistrationsAdapter
instance providing such components.
If you want to take complete control of Spring MVC, you can add your own @Configuration
annotated with @EnableWebMvc
.
2. 扩展SpringMVC
==编写一个配置类(@Configuration),是WebMvcConfigurerAdapter类型;不能标注@EnableWebMvc==;
既保留了所有的自动配置,也能用我们扩展的配置;
/**
* @Author cyy
* @Date 2018/8/13 11:11
* @Version 1.0
* @Blog http://pccwcyy.club/wordpress/
**/
//使用 WebMvcConfigurationSupport 可以来扩展SpringMVC的功能
@Configuration
public class MyMvcConfig extends WebMvcConfigurationSupport {
@Override
protected void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//浏览器发送/cyy,请求来到success页面
registry.addViewController("/cyy").setViewName("success");
}
}
原理:
1)WebMvcAutoConfiguration是SpringMVC的自动配置类
2)在做其他自动配置时会导入;@Import(**EnableWebMvcConfiguration**.class)
@Configuration
public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
private final WebMvcConfigurerComposite configurers = new WebMvcConfigurerComposite();
//从容器中获取所有的WebMvcConfigurer
@Autowired(required = false)
public void setConfigurers(List configurers) {
if (!CollectionUtils.isEmpty(configurers)) {
this.configurers.addWebMvcConfigurers(configurers);
//一个参考实现;将所有的WebMvcConfigurer相关配置都来一起调用;
@Override
// public void addViewControllers(ViewControllerRegistry registry) {
// for (WebMvcConfigurer delegate : this.delegates) {
// delegate.addViewControllers(registry);
// }
}
}
}
3)容器中所有的WebMvcConfigurer都会一起起作用;
4)我们的配置类也会被调用;
效果:SpringMVC的自动配置和我们的扩展配置都会起作用;
3. 全面接管SpringMVC;
SpringBoot对SpringMVC的自动配置不需要了,所有都是我们自己配置;所有的SpringMVC的自动配置都失效了
我们需要在配置类中添加@EnableWebMvc即可;
//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
@EnableWebMvc
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//浏览器发送 /atguigu 请求来到 success
registry.addViewController("/atguigu").setViewName("success");
}
}
原理:
为什么@EnableWebMvc自动配置就失效了;
1)@EnableWebMvc的核心
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
2)
@Configuration
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
3)
@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class,
WebMvcConfigurerAdapter.class })
//容器中没有这个组件的时候,这个自动配置类才生效
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
4)@EnableWebMvc将WebMvcConfigurationSupport组件导入进来;
5)导入的WebMvcConfigurationSupport只是SpringMVC最基本的功能;
5. 如何修改SpringBoot的默认配置
模式:
1)、SpringBoot在自动配置很多组件的时候,先看容器中有没有用户自己配置的(@Bean、@Component)如果有就用用户配置的,如果没有,才自动配置;如果有些组件可以有多个(ViewResolver)将用户配置的和自己默认的组合起来;
2)、在SpringBoot中会有非常多的xxxConfigurer帮助我们进行扩展配置
3)、在SpringBoot中会有很多的xxxCustomizer帮助我们进行定制配置
6. RestfulCRUD
1)默认访问首页
//使用WebMvcConfigurerAdapter可以来扩展SpringMVC的功能
//@EnableWebMvc 不要接管SpringMVC
@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
// super.addViewControllers(registry);
//浏览器发送 /atguigu 请求来到 success
registry.addViewController("/atguigu").setViewName("success");
}
//所有的WebMvcConfigurerAdapter组件都会一起起作用
@Bean //将组件注册在容器
public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("login");
registry.addViewController("/index.html").setViewName("login");
}
};
return adapter;
}
}
2)国际化
一般的Spring做国际化的步骤:
1)编写国际化配置文件;
2)使用ResourceBundleMessageSource管理国际化资源文件
3)在页面使用fmt:message取出国际化内容
SpringBoot中做国际化的步骤:
1)编写国际化配置文件,抽取页面需要显示的国际化消息
2)SpringBoot自动配置好了管理国际化资源文件的组件;
@ConfigurationProperties(prefix = "spring.messages")
public class MessageSourceAutoConfiguration {
/**
* Comma-separated list of basenames (essentially a fully-qualified classpath
* location), each following the ResourceBundle convention with relaxed support for
* slash based locations. If it doesn't contain a package qualifier (such as
* "org.mypackage"), it will be resolved from the classpath root.
*/
private String basename = "messages";
//我们的配置文件可以直接放在类路径下叫messages.properties;
@Bean
public MessageSource messageSource() {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
if (StringUtils.hasText(this.basename)) {
//设置国际化资源文件的基础名(去掉语言国家代码的)
messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray(
StringUtils.trimAllWhitespace(this.basename)));
}
if (this.encoding != null) {
messageSource.setDefaultEncoding(this.encoding.name());
}
messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale);
messageSource.setCacheSeconds(this.cacheSeconds);
messageSource.setAlwaysUseMessageFormat(this.alwaysUseMessageFormat);
return messageSource;
}
3)去页面获取国际化的值;
先设置项目的编码为UTF-8:File->Setting->File Encodings,记得勾选 Transparent xxx;
Signin Template for Bootstrap
这样的做的效果:根据浏览器语言设置的信息切换了国际化;
原理:
国际化Locale(区域信息对象);LocaleResolver(获取区域信息对象);
@Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
public LocaleResolver localeResolver() {
if (this.mvcProperties
.getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
return new FixedLocaleResolver(this.mvcProperties.getLocale());
}
AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
return localeResolver;
}
默认的就是根据请求头带来的区域信息获取Locale进行国际化
4)点击链接切换国际化
/**
* 可以在链接上携带区域信息
*/
public class MyLocaleResolver implements LocaleResolver {
@Override
public Locale resolveLocale(HttpServletRequest request) {
String l = request.getParameter("l");
Locale locale = Locale.getDefault();
if(!StringUtils.isEmpty(l)){
String[] split = l.split("_");
locale = new Locale(split[0],split[1]);
}
return locale;
}
@Override
public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
}
}
@Bean
public LocaleResolver localeResolver(){
return new MyLocaleResolver();
}
}
3)登陆
开发期间模板引擎页面修改以后,要实时生效
1)禁用模板引擎的缓存
# 禁用缓存
spring.thymeleaf.cache=false
2)页面修改完成以后ctrl+f9:重新编译;
登陆错误消息的显示
4)拦截器进行登陆检查
拦截器
/**
* 登陆检查,
*/
public class LoginHandlerInterceptor implements HandlerInterceptor {
//目标方法执行之前
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
Object user = request.getSession().getAttribute("loginUser");
if(user == null){
//未登陆,返回登陆页面
request.setAttribute("msg","没有权限请先登陆");
request.getRequestDispatcher("/index.html").forward(request,response);
return false;
}else{
//已登陆,放行请求
return true;
}
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
}
}
注册拦截器
//所有的WebMvcConfigurerAdapter组件都会一起起作用
@Bean //将组件注册在容器
public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){
WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() {
@Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("login");
registry.addViewController("/index.html").setViewName("login");
registry.addViewController("/main.html").setViewName("dashboard");
}
//注册拦截器
@Override
public void addInterceptors(InterceptorRegistry registry) {
//super.addInterceptors(registry);
//静态资源; *.css , *.js
//SpringBoot已经做好了静态资源映射
registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**")
.excludePathPatterns("/index.html","/","/user/login");
}
};
return adapter;
}