SpringBoot過濾器與攔截器深入分析實(shí)現(xiàn)方法

第SpringBoot過濾器與攔截器深入分析實(shí)現(xiàn)方法目錄過濾器編寫過濾器注冊過濾器基于FilterRegistrationBean基于@WebFilter攔截器

過濾器

實(shí)現(xiàn)過濾器需要實(shí)現(xiàn)javax.servlet.Filter接口。重寫三個(gè)方法。其中init()方法在服務(wù)啟動(dòng)時(shí)執(zhí)行，destroy()在服務(wù)停止之前執(zhí)行。

可用兩種方式注冊過濾器：

使用FilterRegistrationBean來注入。可使用setOrder(0)設(shè)置過濾器的優(yōu)先級，越小優(yōu)先級越高。使用@WebFilter(filterName=myFilter2,urlPatterns=/*)配合@ServletComponentScan()實(shí)現(xiàn)注入。（@Order注解無效）

編寫過濾器

packagecom.example.recorddemo.filters;

importjavax.servlet.*;

importjavax.servlet.http.HttpServletRequest;

importjava.io.IOException;

publicclassMyFilter1implementsFilter{

@Override

publicvoidinit(FilterConfigfilterConfig)throwsServletException{

System.out.println("初始化過濾器："+filterConfig.getFilterName());

@Override

publicvoiddoFilter(ServletRequestservletRequest,ServletResponseservletResponse,FilterChainfilterChain)throwsIOException,ServletException{

System.out.println("在請求之前做處理");

if(servletRequestinstanceofHttpServletRequest){

System.out.println("URL:"+((HttpServletRequest)servletRequest).getRequestURL());

//調(diào)用filter鏈中的下一個(gè)filter

filterChain.doFilter(servletRequest,servletResponse);

System.out.println("在請求之后做處理");

@Override

publicvoiddestroy(){

System.out.println("銷毀：MyFilter1");

}

注冊過濾器

基于FilterRegistrationBean

在配置類中注冊一個(gè)FilterRegistrationBean類型的Bean。

如果沒有設(shè)置UrlPatterns，那么會(huì)自動(dòng)關(guān)聯(lián)到/*上。如果沒有設(shè)置過濾器的名字，那么會(huì)自動(dòng)推理出一個(gè)過濾器名稱（bean的名字）

WhennoURLpatternorservletsarespecifiedthefilterwillbeassociatedto/*.Thefilternamewillbededucedifnotspecified.

fileter默認(rèn)是enable的，將其設(shè)置為false表示關(guān)閉當(dāng)前過濾器?？赏ㄟ^setOrder(0)方法設(shè)置過濾器的優(yōu)先級，如果優(yōu)先級相同，則先定義的優(yōu)先級更高。

@Configuration

publicclassFilterConfiguration{

@Bean

publicFilterRegistrationBeanmyFilter1(){

MyFilter1filter=newMyFilter1();

FilterRegistrationBeanfilterRegistrationBean=newFilterRegistrationBean(filter);

//filterRegistrationBean.addUrlPatterns("/*");

//filterRegistrationBean.setEnabled(true);

returnfilterRegistrationBean;

基于@WebFilter

使用@WebFilter修飾filter。在任意configuration類中添加@ServletComponentScan(com.example.recorddemo.filters)，包名可以不填。

importjavax.servlet.*;

importjavax.servlet.annotation.WebFilter;

importjavax.servlet.http.HttpServletRequest;

importjava.io.IOException;

@WebFilter(filterName="myFilter2",urlPatterns="/*")

publicclassMyFilter2implementsFilter{

@Override

publicvoidinit(FilterConfigfilterConfig)throwsServletException{}

@Override

publicvoiddoFilter(ServletRequestservletRequest,ServletResponseservletResponse,FilterChainfilterChain)throwsIOException,ServletException{

//調(diào)用filter鏈中的下一個(gè)filter

filterChain.doFilter(servletRequest,servletResponse);

@Override

publicvoiddestroy(){}

}

攔截器

攔截器會(huì)在處理指定請求之前和之后進(jìn)行相關(guān)操作，配置攔截器需要兩步

編寫攔截器類（實(shí)現(xiàn)HandlerInterceptor接口）添加已實(shí)現(xiàn)的攔截器（實(shí)現(xiàn)WebMvcConfigurer接口，并重寫addInterceptors()方法）添加addPathPatterns()規(guī)定攔截哪些請求。（/*表示只攔截/下的所有目錄，但是不包括子目錄,/**表示攔截/下的所有目錄，及其子目錄）

攔截器類：

packageerceptor;

importorg.springframework.stereotype.Component;

importorg.springframework.web.servlet.HandlerInterceptor;

importorg.springframework.web.servlet.ModelAndView;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

*@authorwangchao

@Component

publicclassMyInterceptorimplementsHandlerInterceptor{

@Override

publicbooleanpreHandle(HttpServletRequestrequest,HttpServletResponseresponse,Objecthandler)throwsException{

//handle可拿到執(zhí)行方法的反射對象。

System.out.println("preHandle:MyInterceptor");

returntrue;

@Override

publicvoidpostHandle(HttpServletRequestrequest,HttpServletResponseresponse,Objecthandler,ModelAndViewmodelAndView)throwsException{

//對于RESTful接口用處不大

@Override

publicvoidafterCompletion(HttpServletRequestrequest,HttpServletResponseresponse,Objecthandler,Exceptionex)throwsException{

//可捕捉異常，但是springboot已經(jīng)有了全局異常捕捉

}

配置攔截器：

packagecom.example.recorddemo.configuration;

importerceptor.MyInterceptor;

importorg.springframework.beans.factory.annotation.Autowired;

importorg.springframework.context.annotation.Configuration;

importorg.springframework.web.servlet.HandlerInterceptor;

importorg.springframework.web.servlet.config.annotation.InterceptorRegistration;

importorg.springframework.web.servlet.config.annotation.InterceptorRegistry;

importorg.springframework.web.servlet.config.annotation.WebMvcConfigurer;

importjavax.annotation.Resource;

@Configuration

publicclassInterceptorConfigurationimplementsWebMvcConfigurer{

@Resource

MyInterceptormyInterceptor;

*添加攔截器

*@paramregistry

@Override

publicvoidaddInterceptors(InterceptorRegistryregistry){

registry.addInterceptor(myInterceptor).addPathPatterns("/**");

}

registry.addInterceptor()方法會(huì)返回當(dāng)前的interceptor，因此可直接執(zhí)行addPathPatterns()方法

publicInterceptorRegistrationaddInterceptor(HandlerInterceptorinterceptor){

InterceptorRe