第SpringBoot過濾器與攔截器深入分析實現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

實現過濾器需要實現javax.servlet.Filter接口。重寫三個方法。其中init()方法在服務啟動時執行，destroy()在服務停止之前執行。

可用兩種方式注冊過濾器：

使用FilterRegistrationBean來注入。可使用setOrder(0)設置過濾器的優先級，越小優先級越高。使用@WebFilter(filterName=myFilter2,urlPatterns=/*)配合@ServletComponentScan()實現注入。（@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());

//調用filter鏈中的下一個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FilterRegistrationBean類型的Bean。

如果沒有設置UrlPatterns，那么會自動關聯到/*上。如果沒有設置過濾器的名字，那么會自動推理出一個過濾器名稱（bean的名字）

WhennoURLpatternorservletsarespecifiedthefilterwillbeassociatedto/*.Thefilternamewillbededucedifnotspecified.

fileter默認是enable的，將其設置為false表示關閉當前過濾器?？赏ㄟ^setOrder(0)方法設置過濾器的優先級，如果優先級相同，則先定義的優先級更高。

@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{

//調用filter鏈中的下一個filter

filterChain.doFilter(servletRequest,servletResponse);

@Override

publicvoiddestroy(){}

}

攔截器

攔截器會在處理指定請求之前和之后進行相關操作，配置攔截器需要兩步

編寫攔截器類（實現HandlerInterceptor接口）添加已實現的攔截器（實現WebMvcConfigurer接口，并重寫addInterceptors()方法）添加addPathPatterns()規定攔截哪些請求。（/*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()方法會返回當前的interceptor，因此可直接執行addPathPatterns()方法

publicInterceptorRegistrationaddInterceptor(HandlerInterceptorinterceptor){

InterceptorRe