【使用篇二】SpringBoot整合Filter（2）

两种方式：

• 通过注解扫描完成 Filter 组件的注册
• 通过方法完成 Filter 组件的注册

一、通过注解扫描完成 Filter 组件的注册

1. 编写Filter类

/**
 * SpringBoot整合Filter方式一
 *
 * 传统方式
 * <filter>
 *         <filter-name>FirstFilter</filter-name>
 *         <filter-class>com.linhw.demo.filter.FirstFilter</filter-class>
 * </filter>
 *
 * <filter-mapping>
 *         <filter-name>FirstFilter</filter-name>
 *         <url-pattern>/filter</url-pattern>
 * </filter-mapping>
 */
@WebFilter(filterName="FirstFilter", urlPatterns={"/filter"})
public class FirstFilter implements Filter{

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        System.out.println("FirstFilter 进入......");
        arg2.doFilter(arg0, arg1);
        System.out.println("FirstFilter 离开......");
    }

    @Override
    public void destroy() {

    }

}

2. 编写启动类

@SpringBootApplication
@ServletComponentScan //扫描，并实例化类
public class App3 {

    public static void main(String[] args) {
        SpringApplication.run(App3.class, args);
    }

}

二、通过方法完成 Filter 组件的注册

1. 编写Filter类

//区别于第一种方式，没有使用注解
public class SecondFilter implements Filter{
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        System.out.println("SecondFilter 进入......");
        arg2.doFilter(arg0, arg1);
        System.out.println("SecondFilter 离开......");
    }

    @Override
    public void destroy() {

    }
}

2. 编写启动类

@SpringBootApplication
public class App4 {

    public static void main(String[] args) {
        SpringApplication.run(App4.class, args);
    }

    //使用@Bean注解将名为"getFilter"的bean加入到容器
    @Bean
    public FilterRegistrationBean getFilter(){
        FilterRegistrationBean secondFilter = new FilterRegistrationBean(new SecondFilter());
        secondFilter.addUrlPatterns(new String[]{"/filter"});
        return secondFilter;
    }
}