Springboot使用Filter以及踩过的坑

在Springboot中使用Filter有两种方式,注解方式,注册bean方式

一、注解@WebFilter

1、实现Filter接口(javax.servlet)

2、添加@WebFilter注解

3、启动类添加@ServletComponentScan注解

附上代码:

第一个Filter:

@Slf4j
@WebFilter(filterName = "filter1", urlPatterns = {"/url1/*"})
public class Filter1_Filter implements Filter { @Override
public void init(FilterConfig filterConfig) throws ServletException { } @Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
log.info("do filter1");
filterChain.doFilter(servletRequest, servletResponse);
} @Override
public void destroy() { } }

第二个Filter:

@Slf4j
@WebFilter(filterName = "filter2", urlPatterns = {"/url2/*"})
public class Filter2_Filter implements Filter { @Override
public void init(FilterConfig filterConfig) throws ServletException { } @Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
log.info("do filter2");
filterChain.doFilter(servletRequest, servletResponse);
} @Override
public void destroy() { } }

启动类:

@SpringBootApplication
@ServletComponentScan
public class MyApplication { public static void main(String[] args) {
SpringApplication.run(MyApplication .class, args);
} }

下面说说我踩过的坑

1、不加@ServletComponentScan注解无法注入Filter,这个注解的作用就是去扫描@WebServlet、@WebFilter、@WebListener这类特殊注解。如果不加,spring容器是不会主动扫描的

2、多个Filter的执行顺序,说出来你可能不信,这种注解方式实现的Filter是通过Filter的类名首字母来控制执行顺序的,像Filter1_Filter就比Filter2_Filter先执行。但网上一些资料说,当Filter数量很多时,是没有明确的执行顺序的,所以这种方式还是放弃吧,推荐第二种

二、注册bean

1、实现Filter接口

2、注册Filter

下面附上代码:

第一个Filter:

@Slf4j
public class Filter1 implements Filter { @Override
public void init(FilterConfig filterConfig) throws ServletException { } @Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
log.info("do filter1");
filterChain.doFilter(servletRequest, servletResponse);
} @Override
public void destroy() { } }

第二个Filter:

@Slf4j
public class Filter2 implements Filter { @Override
public void init(FilterConfig filterConfig) throws ServletException { } @Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
log.info("do filter2");
filterChain.doFilter(servletRequest, servletResponse);
} @Override
public void destroy() { } }

注册类:

@Configuration
public class FilterConfig { @Bean
public Filter filter1(){
return new Filter1();
} @Bean
public Filter filter2(){
return new Filter2();
} @Bean
public FilterRegistrationBean setFilter1() {
FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
filterRegistrationBean.setFilter(filter1());
filterRegistrationBean.addUrlPatterns("/url1/*");
filterRegistrationBean.setOrder(1); //order的数值越小,在所有的filter中优先级越高
return filterRegistrationBean;
} @Bean
public FilterRegistrationBean setFilter2(){
FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
filterRegistrationBean.setFilter(filter2());
filterRegistrationBean.addUrlPatterns("/url2/*");
filterRegistrationBean.setOrder(2); //order的数值越小,在所有的filter中优先级越高
return filterRegistrationBean;
} }

这种方式就比较严谨了,通过filterRegistrationBean.setOrder(1)设置执行顺序亲测有效

05-11 11:36