spring系列 SpringMVC-拦截器

news2024/11/16 1:15:05

拦截器（Interceptor）是在SpringMVC中动态拦截控制器方法的执行。

拦截器执行流程：

拦截器与过滤器区别

归属不同：Filter属于Servlet技术，Interceptor属于SpringMVC技术

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

拦截器入门案例

@Component

public class ProjectInterceptor implements HandlerInterceptor {

//handler:被调用的处理器对象，本质上是一个方法对象，对反射技术中的Method对象进行了再包装
//原始方法调用前执行的内容
//返回值类型可以拦截控制的执行，true放行，false终止

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
String contentType = request.getHeader("Content-Type");
HandlerMethod hm = (HandlerMethod)handler;
System.out.println("preHandle..."+contentType);
return true;
}

@Override
//原始方法调用后执行的内容
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("postHandle...");
}

@Override
//原始方法调用完成后执行的内容
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

//表现层如果有异常抛出这里可以获取，但我们有统一异常处理，所以这里用得不多
System.out.println("afterCompletion...");
}

}

过滤静态资源

@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
@Autowired
private ProjectInterceptor projectInterceptor;

@Override
protected void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
}

@Override
protected void addInterceptors(InterceptorRegistry registry) {
//添加拦截器并设定拦截的访问路径，路径可以通过可变参数设置多个
registry.addInterceptor(projectInterceptor).addPathPatterns("/books","/books/*");
}
}

定义配置类，com.xxz.config是上面support所在的位置，这样就把support配置上了：

@Configuration
@ComponentScan({"com.xxz.controller","com.xxz.config"})
@EnableWebMvc
//实现WebMvcConfigurer接口可以简化开发，但具有一定的侵入性
public class SpringMvcConfig implements WebMvcConfigurer {
@Autowired
private ProjectInterceptor projectInterceptor;
@Autowired
private ProjectInterceptor2 projectInterceptor2;

@Override
public void addInterceptors(InterceptorRegistry registry) {
//配置多个拦截器
registry.addInterceptor(projectInterceptor).addPathPatterns("/books","/books/*");
registry.addInterceptor(projectInterceptor2).addPathPatterns("/books","/books/*");
}
}