SpringMVC拦截器和拦截器链

1.拦截器概述

1. 拦截器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
2. 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

2.拦截器和过滤器的区别

• 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 仅对 SpringMVC 的访问进行增强。

3.拦截器开发

1. 创建拦截器类，实现 HandlerInterceptor 接口

@Component
public class ProjectInterceptorr implements HandlerInterceptor {
    //原始方法调用前执行的内容
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle......");
        return true;
    }

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

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

2. 配置拦截器类

@Configuration
public class SpringSupport extends WebMvcConfigurationSupport {

    @Autowired
    private ProjectInterceptorr projectInterceptorr;

    //拦截器
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptorr).addPathPatterns("/books","/books/*");
    }
}

3. SpringMVC 包扫描

@Configuration
@ComponentScan({"com.my.controller","com.my.config"})
@EnableWebMvc
public class SpringMvcConfig {
}

4.拦截器的执行流程

5.拦截器链配置

1.配置多个拦截器

1. 创建拦截器类

@Component
public class ProjectInterceptorr2 implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle2......");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle2......");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion2......");
    }
}

2. 配置拦截器类

@Configuration
public class SpringSupport extends WebMvcConfigurationSupport {

    @Autowired
    private ProjectInterceptorr projectInterceptorr;
    @Autowired
    private ProjectInterceptorr2 projectInterceptorr2;

    //拦截器
    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(projectInterceptorr).addPathPatterns("/books","/books/*");
        registry.addInterceptor(projectInterceptorr2).addPathPatterns("/books","/books/*");
    }
}

2.拦截器链的执行

• 拦截器的执行顺序和配置顺序有关，先进先出。
• 拦截器链的运行顺序参照拦截器添加顺序为准
• 当拦截器链出现对原始处理器的拦截，后面的拦截器终止运行
• 当拦截器运行中断，仅运行配置走在前面的拦截器的 afterCompletion 操作