SpringMVC中的拦截器介绍

超、凢脫俗 2021-09-19 06:50 464阅读 0赞

1.  SpringMvc中的拦截器：
    
    1.  SpringMvc拦截器帮我们按照一定规则拦截请求，后根据开发人员自定义的拦截逻辑进行处理；
    2.  自定义拦截器需要实现**HandlerInterceptor**接口；
    3.  自定义的拦截器实现类需要在SpringMvc配置文件中配置；
    4.  可以配置多个拦截器，配置的顺序会影响到拦截器的执行顺序，配置在前的先执行；
    5.  HandlerInterceptor有3个方法：
        
        1.  preHandle 预处理：在拦截方法前执行；
        2.  postHandle 后处理：在拦截方法后执行；
        3.  afterCompletion 渲染后处理：在页面渲染后执行；
    6.  拦截器也体现了AOP思想；
    7.  拦截器的应用：权限检查，日志记录，性能检测等；
2.  拦截器的执行流程图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70][]

总结的几条拦截器规则：

**1.preHandle 预处理：根据拦截器定义的顺序，正向执行**

**2.postHandle 后处理：根据拦截器定义的顺序，逆向执行。需要所有的preHandle都返回true时才会调用**

**3.afterCompletion 渲染后处理：根据拦截器定义的顺序，逆向执行。preHandle返回true就会调用**

![20190506095935117.png][]

MyInterceptor1.java:

public class MyInterceptor1 implements HandlerInterceptor {
    
    	@Override
    	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    			throws Exception {
    		System.out.println("1 PreHandle预处理");
    		return true;
    	}
    
    	@Override
    	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
    			ModelAndView modelAndView) throws Exception {
    		System.out.println("1 postHandle后处理");
    	}
    
    
    	@Override
    	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
    			throws Exception {
    		System.out.println("1 afterCompletion页面渲染后处理");
    	}
    	
    }

MyInterceptor2.java:

public class MyInterceptor2 implements HandlerInterceptor {
    
    	@Override
    	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    			throws Exception {
    		System.out.println("2 PreHandle预处理");
    		return true;
    	}
    
    	@Override
    	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
    			ModelAndView modelAndView) throws Exception {
    		System.out.println("2 postHandle后处理");
    	}
    
    
    	@Override
    	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
    			throws Exception {
    		System.out.println("2 afterCompletion页面渲染后处理");
    	}
    	
    }

applicationContext.xml:

<mvc:interceptors>
    
    			<mvc:interceptor>
    				<mvc:mapping path="/**"/>
    				<bean class="com.sikiedu.interceptor.MyInterceptor1"></bean>
    			</mvc:interceptor>
    			
    			
    			<mvc:interceptor>
    				<mvc:mapping path="/**"/>
    				<bean class="com.sikiedu.interceptor.MyInterceptor2"></bean>
    			</mvc:interceptor>
    		</mvc:interceptors>

*  **preHandle1返回true，preHandle2返回true：运行结果如下：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 1][]

*  **preHandle1返回true，preHandle2返回false：运行结果如下：**

![20190506101140171.png][]

*  **preHandle1返回false，preHandle2返回true：运行结果如下：**

![20190506101301804.png][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70]: /images/20210725/f0d651c945e7472397fb8d2b69162110.png
[20190506095935117.png]: /images/20210725/7dfa94385f674b7a9809dec9fbf72f8f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMzIzMjU2_size_16_color_FFFFFF_t_70 1]: /images/20210725/55d6d684a39c49599a3e40b9348cb6b2.png
[20190506101140171.png]: /images/20210725/8015c3c323d04438a0982a94a15a7cfd.png
[20190506101301804.png]: /images/20210725/15ec222062724d959e49b95905d403f3.png