1.什麼是攔截器?
攔截器接口及其實現
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
public class LoginInterceptor extends HandlerInterceptorAdapter {
/**
*預處理回調方法,實現處理器的預處理(如登錄檢查)。
*第三個參數爲響應的處理器,即controller。
*返回true,表示繼續流程,調用下一個攔截器或者處理器。
*返回false,表示流程中斷,通過response產生響應。
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
Object handler) throws Exception {
System.out.println("---------------------------->controller調用之前");
return true;
}
/**
*當前請求進行處理之後,也就是Controller方法調用之後執行,
*但是它會在DispatcherServlet 進行視圖返回渲染之前被調用。
*此時我們可以通過modelAndView對模型數據進行處理或對視圖進行處理。
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response,
Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("controller調用完畢");
}
/**
*方法將在整個請求結束之後,也就是在DispatcherServlet 渲染了對應的視圖之後執行。
*這個方法的主要作用是用於進行資源清理工作的。
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
Object handler, Exception ex) throws Exception {
System.out.println("整個請求已經結束");
}
}
攔截器相關配置
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.InterceptorRegistration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@SuppressWarnings("deprecation")
@Component
public class InterceptorConfiguration extends WebMvcConfigurerAdapter {
@Override
public void addInterceptors(InterceptorRegistry registry) {
// 註冊攔截器
InterceptorRegistration ir = registry.addInterceptor(new LoginInterceptor());
// 配置攔截的路徑,指的是哪些請求需要代理模式
ir.addPathPatterns("/student/list");
// 配置不攔截的路徑
ir.excludePathPatterns("/**.html");
// 還可以在這裏註冊其它的攔截器
// registry.addInterceptor(new OtherInterceptor()).addPathPatterns("/**");
}
}
2.什麼是過濾器?
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;
import org.springframework.core.annotation.Order;
@Order(1)
@WebFilter(filterName = "MyFilter", urlPatterns = "/student/create")
public class MyFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
System.out.println("過濾器初始化");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
System.out.println("請求不可達");
}
@Override
public void destroy() {
System.out.println("過濾器銷燬");
}
}
3.什麼是監聽器?
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class MyListener implements ServletRequestListener {
@Override
public void requestDestroyed(ServletRequestEvent servletRequestEvent) {
System.out.println("---------------------------->請求銷燬");
}
@Override
public void requestInitialized(ServletRequestEvent servletRequestEvent) {
System.out.println("---------------------------->請求創建");
}
}