Introduction to methods of implementing filters, listeners, and interceptors through SpringBoot in java

package com.example.filter; 
import java.io.IOException;  
import javax.servlet.Filter; 
import javax.servlet.FilterChain; 
import javax.servlet.FilterConfig; 
import javax.servlet.ServletException; 
import javax.servlet.ServletRequest; 
import javax.servlet.ServletResponse; 
import javax.servlet.annotation.WebFilter; 
/** 
 * 实现javax.servlet.Filter,覆盖其三个方法 
 * @author Administrator 
 * 
 */ 
@WebFilter(filterName="customFilter",urlPatterns="/*") 
public class CustomFilter implements Filter{ 
 
  @Override 
  public void destroy() { 
    System.out.println("CustomFilter过滤器销毁"); 
     
  } 
 
  @Override 
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
      throws IOException, ServletException { 
    System.out.println("CustomFilter指定过滤器操作......"); 
    //执行操作后必须doFilter 
    chain.doFilter(request, response); 
  } 
 
  @Override 
  public void init(FilterConfig arg0) throws ServletException { 
    System.out.println("CustomFilter初始化......"); 
  }     
}

package com.example.listener;  
import javax.servlet.ServletContextEvent; 
import javax.servlet.ServletContextListener; 
import javax.servlet.annotation.WebListener; 
 
/** 
 * 实现ServletContextListener，覆盖其两个方法 
 * @author Administrator 
 * 
 */ 
@WebListener 
public class CustomListener implements ServletContextListener{ 
 
  @Override 
  public void contextDestroyed(ServletContextEvent servletContext) { 
    System.out.println("servletContext销毁......"); 
     
  } 
 
  @Override 
  public void contextInitialized(ServletContextEvent servletContext) { 
    System.out.println("servletContext初始化......"); 
  } 
 
}

package com.example.listener;  
import javax.servlet.annotation.WebListener; 
import javax.servlet.http.HttpSessionEvent; 
import javax.servlet.http.HttpSessionListener; 
 
/** 
 * 实现HttpSessionListener接口，监视session的动态 
 * @author Administrator 
 * 
 */ 
@WebListener 
public class SessionListener implements HttpSessionListener{ 
 
  @Override 
  public void sessionCreated(HttpSessionEvent session) { 
    System.out.println("session创建成功......"); 
     
  } 
 
  @Override 
  public void sessionDestroyed(HttpSessionEvent session) { 
    System.out.println("session销毁......"); 
     
  } 
 
}

package com.example.Interceptor;  
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import org.springframework.web.servlet.HandlerInterceptor; 
import org.springframework.web.servlet.ModelAndView; 
 
public class CustomInterceptor implements HandlerInterceptor { 
 
  @Override 
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object object, 
      Exception exception) throws Exception { 
    //在整个请求结束之后被调用，也就是在DispatcherServlet 渲染了对应的视图之后执行（主要是用于进行资源清理工作） 
    System.out.println("3. 整个请求结束之后被调用......CustomInterceptor1......"); 
  } 
 
  @Override 
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object object, ModelAndView view) 
      throws Exception { 
    // 请求处理之后进行调用，但是在视图被渲染之前 
    System.out.println("2. 请求处理之后进行调用，但是在视图被渲染之前......CustomInterceptor1......"); 
  } 
 
  @Override 
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object object) throws Exception { 
    // 在请求处理之前进行调用 
    System.out.println("1. 在请求处理之前进行调用......CustomInterceptor1......"); 
    // 只有返回true才会继续向下执行，返回false取消当前请求 
    return true; 
  } 
 
}

package com.example.Interceptor; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import org.springframework.web.servlet.HandlerInterceptor; 
import org.springframework.web.servlet.ModelAndView; 
 
public class CustomInterceptor2 implements HandlerInterceptor { 
 
  @Override 
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object object, 
      Exception exception) throws Exception { 
    //在整个请求结束之后被调用，也就是在DispatcherServlet 渲染了对应的视图之后执行（主要是用于进行资源清理工作） 
    System.out.println("3. 整个请求结束之后被调用......CustomInterceptor2......"); 
  } 
 
  @Override 
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object object, ModelAndView view) 
      throws Exception { 
    // 请求处理之后进行调用，但是在视图被渲染之前 
    System.out.println("2. 请求处理之后进行调用，但是在视图被渲染之前......CustomInterceptor2......"); 
  } 
 
  @Override 
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object object) throws Exception { 
    // 在请求处理之前进行调用 
    System.out.println("1. 在请求处理之前进行调用......CustomInterceptor2......"); 
    // 只有返回true才会继续向下执行，返回false取消当前请求 
    return true; 
  } 
 
}

package com.example.adapter; 
 
import org.springframework.context.annotation.Configuration; 
import org.springframework.web.servlet.config.annotation.InterceptorRegistry; 
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter; 
 
import com.example.Interceptor.CustomInterceptor; 
import com.example.Interceptor.CustomInterceptor2; 
 
/** 
 * 继承WebMvcConfigurerAdapter，复写addInterceptors方法 
 * @author Administrator 
 * 
 */ 
@Configuration 
public class WebAdapter extends WebMvcConfigurerAdapter{ 
 
  @Override 
  public void addInterceptors(InterceptorRegistry registry) { 
    //众多的拦截器组成了一个拦截器链 
    /** 
     * 主要方法说明： 
     * addPathPatterns 用于添加拦截规则 
     * excludePathPatterns 用户排除拦截 
     */ 
    registry.addInterceptor(new CustomInterceptor()).addPathPatterns("/*"); 
    registry.addInterceptor(new CustomInterceptor2()).addPathPatterns("/*"); 
    super.addInterceptors(registry); 
  } 
}