拦截器

• 拦截器（Interceptor）是一种动态拦截方法调用的机制，在SpringMVC中动态拦截控制器方法的执行

• 作用：在指定的方法调用前后执行预先设定的代码，阻止原始方法的执行

   

拦截器&过滤器

• 归属不同：Filter属于Servlet技术，Interception属于SpringMVC技术

• 拦截内容不同：Filter对所有访问进行增强，Interception仅针对SpringMVC的访问进行增强。

拦截器执行流程

---perHandle --->return----->controller----->postHandle---->afterCompletion----->

---->false---------------------------跳过这一环了-------------------------->

代码

• Interception

package com.yang.controller.Interception;
​
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
​
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@Component
public class ProjectInterception implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle...");
        return true;
    }
​
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle...");
​
    }
​
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion...");
​
    }
}
​

• SpringMvcSupport

package com.yang.config;
​
import com.yang.controller.Interception.ProjectInterception;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    @Autowired
    private ProjectInterception projectInterception;
​
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
    }
​
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterception).addPathPatterns("/books");
    }
}
​

package com.yang.config;
​
​
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
​
@Configuration
@ComponentScan({"com.yang.controller","com.yang.config"})
@EnableWebMvc//开启接受json
public class SpringMvcConfig {
}

配置拦截器链

• 拦截器链的运行顺序

  • true

  1. perHandle：与配置顺序相同，必定运行

  2. postHandle:与配置顺序相反，可能不运行

  3. afterCompletion：与配置顺序相反，可能不运行

  • • false

    1. perHandle：终止了

    2. postHandle; 终止

    3. afterCompletion：到哪一个perHandle终止，则执行它前面的afterCompletion。