SpringBoot过滤器与拦截器深入分析实现方法

第SpringBoot过滤器与拦截器深入分析实现方法目录过滤器编写过滤器注册过滤器基于FilterRegistrationBean基于@WebFilter拦截器

过滤器

实现过滤器需要实现javax.servlet.Filter接口。重写三个方法。其中init()方法在服务启动时执行，destroy()在服务停止之前执行。

可用两种方式注册过滤器：

使用FilterRegistrationBean来注入。可使用setOrder(0)设置过滤器的优先级，越小优先级越高。使用@WebFilter(filterName=myFilter2,urlPatterns=/*)配合@ServletComponentScan()实现注入。（@Order注解无效）

编写过滤器

packagecom.example.recorddemo.filters;

importjavax.servlet.*;

importjavax.servlet.http.HttpServletRequest;

importjava.io.IOException;

publicclassMyFilter1implementsFilter{

@Override

publicvoidinit(FilterConfigfilterConfig)throwsServletException{

System.out.println("初始化过滤器："+filterConfig.getFilterName());

@Override

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

System.out.println("在请求之前做处理");

if(servletRequestinstanceofHttpServletRequest){

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

//调用filter链中的下一个filter

filterChain.doFilter(servletRequest,servletResponse);

System.out.println("在请求之后做处理");

@Override

publicvoiddestroy(){

System.out.println("销毁：MyFilter1");

}

注册过滤器

基于FilterRegistrationBean

在配置类中注册一个FilterRegistrationBean类型的Bean。

如果没有设置UrlPatterns，那么会自动关联到/*上。如果没有设置过滤器的名字，那么会自动推理出一个过滤器名称（bean的名字）

WhennoURLpatternorservletsarespecifiedthefilterwillbeassociatedto/*.Thefilternamewillbededucedifnotspecified.

fileter默认是enable的，将其设置为false表示关闭当前过滤器。可通过setOrder(0)方法设置过滤器的优先级，如果优先级相同，则先定义的优先级更高。

@Configuration

publicclassFilterConfiguration{

@Bean

publicFilterRegistrationBeanmyFilter1(){

MyFilter1filter=newMyFilter1();

FilterRegistrationBeanfilterRegistrationBean=newFilterRegistrationBean(filter);

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

//filterRegistrationBean.setEnabled(true);

returnfilterRegistrationBean;

基于@WebFilter

使用@WebFilter修饰filter。在任意configuration类中添加@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{

//调用filter链中的下一个filter

filterChain.doFilter(servletRequest,servletResponse);

@Override

publicvoiddestroy(){}

}

拦截器

拦截器会在处理指定请求之前和之后进行相关操作，配置拦截器需要两步

编写拦截器类（实现HandlerInterceptor接口）添加已实现的拦截器（实现WebMvcConfigurer接口，并重写addInterceptors()方法）添加addPathPatterns()规定拦截哪些请求。（/*表示只拦截/下的所有目录，但是不包括子目录,/**表示拦截/下的所有目录，及其子目录）

拦截器类：

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可拿到执行方法的反射对象。

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

returntrue;

@Override

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

//对于RESTful接口用处不大

@Override

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

//可捕捉异常，但是springboot已经有了全局异常捕捉

}

配置拦截器：

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;

*添加拦截器

*@paramregistry

@Override

publicvoidaddInterceptors(InterceptorRegistryregistry){

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

}

registry.addInterceptor()方法会返回当前的interceptor，因此可直接执行addPathPatterns()方法

publicInterceptorRegistrationaddInterceptor(HandlerInterceptorinterceptor){

InterceptorRe