拦截器概念
- 拦截器（Interceptor）是一种动态拦截方法调用的机制
- 作用：
- 在指定的方法调用前后执行预先设定后的代码
- 阻止原始方法执行
拦截器与过滤器的区别
- 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
入门案例
声明拦截器的bean，并实现HandlerInterceptor接口（注意：扫描加载bean）
@Component
public class ProjectInterceptor 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...");
}
}
定义配置类，继承WebMvcConfigrationSupport,实现addInterceptor方法（注意：扫描加载配置）
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
@Override
protected void addInterceptors(InterceptorRegistry registry) {
...
}
}
添加拦截器并设定拦截的访问路径，路径可以通过多个可变参数设置
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
@Autowired
private ProjectInterceptor projectInterceptor;
// 静态资源配置（允许网页打开这些路径，否则静态资源无法在网页上访问）
@Override
protected void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
}
// 拦截器配置
@Override
protected void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(projectInterceptor).addPathPatterns("/books","/books/*"); // 参数可设置多个
}
}
或者直接使用标准接口WebMvcConfigurer简化开发（注意：侵入式较强）
@Configuration
@ComponentScan("com.cqupt.controller")
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer {
@Autowired
private ProjectInterceptor projectInterceptor;
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(projectInterceptor).addPathPatterns("/books","/books/*");
}
}
执行流程
无拦截器
有拦截器
