1、springboot整合servlet
(1)编写servlet类
@WebServlet(name = "myServlet",urlPatterns = "/srv")
public class MyServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("111");
super.doGet(req, resp);
}
}
(2)在启动类上添加如下配置
@SpringBootApplication
@ServletComponentScan
public class ConfigApplication {
public static void main(String[] args) {
SpringApplication.run(ConfigApplication.class, args);
}
@Bean
public ServletRegistrationBean<MyServlet> getServletRegistrationBean(){
ServletRegistrationBean<MyServlet> bean = new ServletRegistrationBean<>(new MyServlet());
bean.setLoadOnStartup(1);
return bean;
}
}
SpringBoot自定义过滤器filter
- @WebFilter + @ServletComponentScan
@Order(int)
注解,配合@WebFilter
注解使用,用于多个过滤器时定义执行顺序,值越小越先执行。- 限定 Filter 的类名,比如刚才那个 Filter 叫 MyFilter ,加入我们现在新写了一个 Filter 叫 AlibabaFilter ,那么顺序就是
AlibabaFilter > MyFilter
- 编写filter类
- urlPatterns
/user/*
通配符
@WebFilter(urlPatterns = {"/user/*"})
@WebFilter(filterName = "MyFilter", urlPatterns = "/filter/*")
public class MyFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
System.out.println("init");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
System.out.println("filter");
chain.doFilter(request,response);
}
@Override
public void destroy() {
System.out.println("destory");
}
}
@SpringBootApplication
@ServletComponentScan
public class FreemarkerwordApplication {
public static void main(String[] args) {
SpringApplication.run(FreemarkerwordApplication.class, args);
}
}
- 使用 SpringBoot 提供的 FilterRegistrationBean
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean<UserFilter> filterRegistrationBean() {
FilterRegistrationBean<UserFilter> bean = new FilterRegistrationBean<>();
bean.setFilter(new UserFilter()); // 这里可以使用 new,也可以在 Filter 上加 @Component 注入进来
bean.addUrlPatterns("/user/*");
bean.setName("loggerFilter");
bean.setOrder(1); // 值越小,优先级越高
return bean;
}
// 可以写多个 FilterRegistrationBean
}
监听器
(4)编写监听器
listener是servlet规范定义的一种特殊类,用于监听servletContext,HttpSession和ServletRequest等域对象的创建和销毁事件。监听域对象的属性发生修改的事件,用于在事件发生前、发生后做一些必要的处理。可用于以下方面:1、统计在线人数和在线用户2、系统启动时加载初始化信息3、统计网站访问量4、记录用户访问路径。
编写监听器类
package com.osvue.config;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
public class MyHttpSessionListener implements HttpSessionListener {
public static int online=0;
@Override
public void sessionCreated(HttpSessionEvent se) {
System.out.println("创建session");
online++;
}
@Override
public void sessionDestroyed(HttpSessionEvent se) {
System.out.println("销毁session");
}
}
添加到配置类
package com.osvue.config;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
@Bean
public ServletListenerRegistrationBean listenerRegist(){
ServletListenerRegistrationBean srb = new ServletListenerRegistrationBean();
srb.setListener(new MyHttpSessionListener());
System.out.println("listener");
return srb;
}
}
添加控制层代码
package com.osvue.controller;
import com.osvue.config.MyHttpSessionListener;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
@Controller
public class ThymeleafController {
@RequestMapping("/login")
public String login(HttpServletRequest request){
HttpSession session = request.getSession(true);
return "login";
}
@RequestMapping("online")
@ResponseBody
public String online(){
return "当前在线人数:"+MyHttpSessionListener.online +"人";
}
}
先发送login请求,然后再发送online的请求
静态资源的配置
- 默认情况下,Spring Boot 将在 classpath 或者 ServletContext 根目录下从名为 /static (/public、/resources 或 /META-INF/resources)目录中服务静态内容。它使用了 Spring MVC 的 ResourceHttpRequestHandler,因此您可以通过添加自己的 WebMvcConfigurerAdapter 并重写 addResourceHandlers 方法来修改此行为。
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
if (!this.resourceProperties.isAddMappings()) {
logger.debug("Default resource handling disabled");
return;
}
Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
if (!registry.hasMappingForPattern("/webjars/**")) {
customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
.addResourceLocations("classpath:/META-INF/resources/webjars/")
.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
}
String staticPathPattern = this.mvcProperties.getStaticPathPattern();
if (!registry.hasMappingForPattern(staticPathPattern)) {
customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
}
}
(1)加载webjars文件
在pom文件中添加jquery的相关依赖,直接可以通过浏览器访问到http://localhost:8080/webjars/jquery/3.4.1/jquery.js
<dependency>
<groupId>org.webjars</groupId>
<artifactId>jquery</artifactId>
<version>3.4.1</version>
</dependency>
(2)加载静态资源
当查找静态资源的时候能够发现静态资源的路径是/**,会去ResourceProperties这个类,可以看到对应的资源目录。
@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties {
private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
"classpath:/resources/", "classpath:/static/", "classpath:/public/" };
/**
* Locations of static resources. Defaults to classpath:[/META-INF/resources/,
* /resources/, /static/, /public/].
*/
private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
private String[] appendSlashIfNecessary(String[] staticLocations) {
String[] normalized = new String[staticLocations.length];
for (int i = 0; i < staticLocations.length; i++) {
String location = staticLocations[i];
normalized[i] = location.endsWith("/") ? location : location + "/";
}
return normalized;
}
可以看到静态资源的目录一共有如下几个:
"/META-INF/resources/"
"classpath:/resources/"
"classpath:/static/"
"classpath:/public/"
springmvc的扩展
springmvc框架是一个mvc的web框架,springmvc允许创建@controller和@RestController bean来处理传入的HTTP请求,控制器种的方法通过@RequestMapping注解映射到HTTP。
Springboot提供了适用于大多数Springmvc应用的自动配置。
引入 ContentNegotiatingViewResolver 和 BeanNameViewResolver bean视图解析器。
支持服务静态资源,包括对 WebJar 的支持。
自动注册 Converter(网页传入的数据封装成对象,完成数据类型的转化)、GenericConverter 和 Formatter bean(将日期转换成规定的格式)。
支持 HttpMessageConverter,用来转换http请求和响应。
自动注册 MessageCodesResolver,定义错误代码生成规则。
支持静态 index.html。
支持自定义 Favicon。
自动使用 ConfigurableWebBindingInitializer bean,将请求树绑定到javaBean中。
自动配置了ViewResolver,就是我们之前学习的SpringMVC的视图解析器:即根据方法的返回值取得视图对象(View),然后由视图对象决定如何渲染(转发,重定向)。
//WebMvcAutoConfiguration
@Bean //我们在这里确实看到已经给容器中注册了一个bean
@ConditionalOnBean({ViewResolver.class})
@ConditionalOnMissingBean(
name = {"viewResolver"},
value = {ContentNegotiatingViewResolver.class}
)
public ContentNegotiatingViewResolver viewResolver(BeanFactory beanFactory) {
ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
resolver.setContentNegotiationManager((ContentNegotiationManager)beanFactory.getBean(ContentNegotiationManager.class));
resolver.setOrder(-2147483648);
return resolver;
}
//ContentNegotiatingViewResolver
@Nullable
public View resolveViewName(String viewName, Locale locale) throws Exception {
RequestAttributes attrs = RequestContextHolder.getRequestAttributes();
Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes");
List<MediaType> requestedMediaTypes = this.getMediaTypes(((ServletRequestAttributes)attrs).getRequest());
if (requestedMediaTypes != null) {
//获取候选的视图对象
List<View> candidateViews = this.getCandidateViews(viewName, locale, requestedMediaTypes);
//选择一个最适合的视图对象,然后把这个对象返回
View bestView = this.getBestView(candidateViews, requestedMediaTypes, attrs);
if (bestView != null) {
return bestView;
}
}
String mediaTypeInfo = this.logger.isDebugEnabled() && requestedMediaTypes != null ? " given " + requestedMediaTypes.toString() : "";
if (this.useNotAcceptableStatusCode) {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Using 406 NOT_ACCEPTABLE" + mediaTypeInfo);
}
return NOT_ACCEPTABLE_VIEW;
} else {
this.logger.debug("View remains unresolved" + mediaTypeInfo);
return null;
}
}
//getCandidateViews
private List<View> getCandidateViews(String viewName, Locale locale, List<MediaType> requestedMediaTypes)
throws Exception {
List<View> candidateViews = new ArrayList<>();
if (this.viewResolvers != null) {
Assert.state(this.contentNegotiationManager != null, "No ContentNegotiationManager set");
for (ViewResolver viewResolver : this.viewResolvers) {
View view = viewResolver.resolveViewName(viewName, locale);
if (view != null) {
candidateViews.add(view);
}
for (MediaType requestedMediaType : requestedMediaTypes) {
List<String> extensions = this.contentNegotiationManager.resolveFileExtensions(requestedMediaType);
for (String extension : extensions) {
String viewNameWithExtension = viewName + '.' + extension;
view = viewResolver.resolveViewName(viewNameWithExtension, locale);
if (view != null) {
candidateViews.add(view);
}
}
}
}
}
if (!CollectionUtils.isEmpty(this.defaultViews)) {
candidateViews.addAll(this.defaultViews);
}
return candidateViews;
}
//initServletContext
@Override
protected void initServletContext(ServletContext servletContext) {
Collection<ViewResolver> matchingBeans =
BeanFactoryUtils.beansOfTypeIncludingAncestors(obtainApplicationContext(), ViewResolver.class).values();
if (this.viewResolvers == null) {
this.viewResolvers = new ArrayList<>(matchingBeans.size());
for (ViewResolver viewResolver : matchingBeans) {
if (this != viewResolver) {
this.viewResolvers.add(viewResolver);
}
}
}
else {
for (int i = 0; i < this.viewResolvers.size(); i++) {
ViewResolver vr = this.viewResolvers.get(i);
if (matchingBeans.contains(vr)) {
continue;
}
String name = vr.getClass().getName() + i;
obtainApplicationContext().getAutowireCapableBeanFactory().initializeBean(vr, name);
}
}
AnnotationAwareOrderComparator.sort(this.viewResolvers);
this.cnmFactoryBean.setServletContext(servletContext);
}
通过上面的代码分析,我们知道了springboot是在容器中去找视图解析器,因此,我们可以给容器自定义添加视图解析器,这个类会帮我们将他组合起来。
//自定义视图解析器
@Bean //放到bean中
public ViewResolver myViewResolver(){
return new MyViewResolver();
}
//我们写一个静态内部类,视图解析器就需要实现ViewResolver接口
private static class MyViewResolver implements ViewResolver{
@Override
public View resolveViewName(String s, Locale locale) throws Exception {
return null;
}
}
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>