SpringMVC学习笔记四:拦截器
拦截器
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的代码
- 阻止原始方法的执行
拦截器与过滤器区别
- 归属不同:Filter属于servlet技术,Interceptor属于SpringMINC技术
- 拦截内容不同:Filter对所有访问进行增强,Interceptor仅针对springWVc的访问进行增强
拦截器配置过程
- 声明拦截器的bean,并实现HandlerInterceptor接口
@Component
public class ProjectInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("preHandle...");
return true;//false,终止原始操作
}
@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WebMvcConfigurationSupport,实现addInterceptor方法
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
@Autowired
HandlerInterceptor ProjectInterceptor;
@Override
protected void addInterceptors(InterceptorRegistry registry) {
//添加拦截器并设定拦截的访问路径,可设置多个
registry.addInterceptor(ProjectInterceptor).addPathPatterns("/books","books/*");
}
}
- 也可以直接在SpringMVC配置类上实现接口WebMvcConfigurer接口(简化配置)
@Configuration
@ComponentScan("controller")
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer{
@Autowired
private HandlerInterceptor ProjectInterceptor;
@Override
public void addInterceptors(InterceptorRegistry registry) {
//添加拦截器并设定拦截的访问路径,可设置多个
registry.addInterceptor(ProjectInterceptor).addPathPatterns("/books","books/*");
}
}
拦截器执行流程
拦截器参数
HttpServletRequest request,:可以从中获取请求体的一些参数
HttpServletResponse response:可以从中获取响应体的一些参数
Object handler:用于获取执行的HandlerMethod方法对象,可以通过反射技术的Method对象进行再包装
ModelAndView modelAndView:封装了用于页面跳转方面的相关数据
Exception ex:可以获取原始程序中获得的异常