SpringMVC自定义拦截器实现过程详解

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
     version="4.0">

  <!--1.注册servlet-->
  <servlet>
    <servlet-name>SpringMVC</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--通过初始化参数指定SpringMVC配置文件的位置，进行关联-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:applicationContext.xml</param-value>
    </init-param>
    <!-- 启动顺序，数字越小，启动越早 -->
    <load-on-startup>1</load-on-startup>
  </servlet>

  <!--所有请求都会被springmvc拦截 -->
  <servlet-mapping>
    <servlet-name>SpringMVC</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

  <!--解决中文乱码问题-->
  <filter>
    <filter-name>encoding</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>utf-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>encoding</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    https://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/mvc
    https://www.springframework.org/schema/mvc/spring-mvc.xsd">

  <!-- 自动扫描指定的包，下面所有注解类交给IOC容器管理 -->
  <context:component-scan base-package="com.min.controller"/>
  <!--注册静态资源-->
  <mvc:default-servlet-handler />
  <!--注解驱动-->
  <mvc:annotation-driven />

  <!-- 解决JSON乱码问题 -->
  <mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
      <bean class="org.springframework.http.converter.StringHttpMessageConverter">
        <constructor-arg value="UTF-8"/>
      </bean>
      <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="objectMapper">
          <bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
            <property name="failOnEmptyBeans" value="false"/>
          </bean>
        </property>
      </bean>
    </mvc:message-converters>
  </mvc:annotation-driven>

  <!-- 视图解析器 -->
  <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
     id="internalResourceViewResolver">
    <!-- 前缀 -->
    <property name="prefix" value="/WEB-INF/jsp/" />
    <!-- 后缀 -->
    <property name="suffix" value=".jsp" />
  </bean>

  <!--拦截器配置-->
  <mvc:interceptors>
    <mvc:interceptor>
      <!--包括这个请求下面的所有请求-->
      <mvc:mapping path="/**"/>
      <bean class="com.min.config.MyInterceptor"/>
    </mvc:interceptor>
  </mvc:interceptors>
</beans>

package com.min.config;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyInterceptor implements HandlerInterceptor {

  // return true; 放行会执行下一个拦截器, 放行
  //return false; 不执行下一个拦截器
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    System.out.println("============处理前============");
    return true;
  }

  /**
  //日志
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    System.out.println("============处理后============");
  }

  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    System.out.println("============清理============");
  }
   */
}

package com.min.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TestController {

  @GetMapping("/t1")
  public String test() {
    System.out.println("TestController=>test()执行了");
    return "ok";

  }
}