springMVC攔截器（interceptors）入門案例

一、首先引入所需要的jar包

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
    <spring.webmvc.version>5.1.5.RELEASE</spring.webmvc.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${spring.webmvc.version}</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
    </dependency>

    <dependency>
      <groupId>javax</groupId>
      <artifactId>javaee-api</artifactId>
      <version>7.0</version>
    </dependency>
  </dependencies>

二、在web.xml中配置springmvc

<?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_3_1.xsd"
         version="3.1">

    <!--springmv核心配置文件-->
    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <!--配置spring.xml存放的路徑-->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springmvc.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>springmvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
</web-app>

三、配置springmvc.xml

<?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 http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <!--開啓註解-->
    <context:component-scan base-package="com.shunli"/>

    <!--註冊攔截器-->
    <!--按照interceptor的先後順序進行攔截-->
    <mvc:interceptors>
        <mvc:interceptor>
            <!--**攔截login下所有的-->
            <mvc:mapping path="/login/**"/>
            <bean class="com.shunli.core.LoginInterceptor"/>
        </mvc:interceptor>
        <mvc:interceptor>
            <!--可以同一個攔截器配置具體的mapping，*只攔截login下一級的-->
            <mvc:mapping path="/login/*"/>
            <mvc:mapping path="/user/usersearch"/>
            <mvc:mapping path="/user/update"/>
            <bean class="com.shunli.core.UserInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

    <!-- SpringMVC註解驅動 -->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <!--bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/-->
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>text/plain;charset=utf-8</value>
                        <value>text/html;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

    <!-- 映射物理路徑 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--配置前綴-->
        <property name="prefix" value="/"/>
        <!--配置後綴-->
        <property name="suffix" value=".jsp"/>
    </bean>
</beans>

四、controller

package com.shunli.controller;

import com.shunli.entity.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpSession;

@Controller
@RequestMapping(value = "/login")
public class LoginController {

    @RequestMapping(value = "/login")
    @ResponseBody
    public String login(){
        System.out.println("2.----LoginController.login");
        return "login";
    }
}

五、攔截器

這裏爲了演示效果，寫了兩個攔截器
第一個

package com.shunli.core;

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

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

/**
 * @author shunli
 */
public class LoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("1、----LoginInterceptor.preHandle------------");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("3、----LoginInterceptor.postHandle------------");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("4、----LoginInterceptor.afterCompletion---------");
    }
}

第二個

package com.shunli.core;

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

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

public class UserInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("1----UserInterceptor.preHandle");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("3----UserInterceptor.postHandle");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("4----UserInterceptor.afterCompletion");
    }
}

當訪問http://localhost:8080/login/login時
在控制檯打印出的結果

1.單個攔截器的順序 preHandle–>具體的Controller–>postHandle–>afterCompletion
2.多個攔截器順序，根據xml中interceptor的先後順序執行
3.多個攔截器執行，後進先出