Java框架（八）--SpringMVC拦截器（1）--拦截器开发流程、多Interceptor执行顺序及preHandle返回值

拦截器-Interceptor

拦截器（Interceptor）用于对URL请求进行前置/后置过滤。
Interceptor与Filter用途相似，但实现方式不同。
Interceptor为SpringMVC的标准组件。
Filter为J2EE的标准组件。
Interceptor底层就是基于Spring AOP面向切面编程实现。

HandlerInterceptor接口

preHandle - 前置执行处理
postHandle - 目标资源已被SpringMVC框架处理
afterCompletion - 响应文本已经产生

拦截器开发流程

Maven依赖servlet-api
实现HandlerInterceptor接口
applicationContext配置过滤地址

新建工程interceptor并把RESTful风格的应用部分的restfull工程源代码复制到当前工程

打开pom.xml引入servlet依赖

        <dependency>
            <groupId>javax.servletgroupId>
            <artifactId>javax.servlet-apiartifactId>
            <version>3.1.0version>
            <scope>providedscope>
            
        dependency>
1
2
3
4
5
6
7
8
9

在com.ql.restful.interceptor包下创建MyInterceptor类

package com.ql.restful.interceptor;

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

public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler) throws Exception {
        System.out.println(request.getRequestURL()+"准备执行");
        return true;
    }

    @Override
    public void postHandle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println(request.getRequestURL()+"-目标处理成功");
    }

    @Override
    public void afterCompletion(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println(request.getRequestURL()+"-响应内容已产生");
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

修改com.ql.restful.controller包下RestfulController类的findPersons方法

    @GetMapping("/persons")
    public List<Person> findPersons(){
        List list = new ArrayList();
        Person person1 = new Person();
        person1.setName("lily");
        person1.setAge(23);
        person1.setBirthday(new Date());
        list.add(person1);
        Person person2 = new Person();
        person2.setName("smith");
        person2.setAge(22);
        person2.setBirthday(new Date());
        list.add(person2);
        System.out.println("RestfulController.findPersons() - return list");
        return list;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

在applicationContext.xml中配置拦截器

    <mvc:interceptors>
        <mvc:interceptor>
            
            
            <mvc:mapping path="/restful/**"/>
            
            <mvc:exclude-mapping path="/**.js"/>
            <mvc:exclude-mapping path="/**.css"/>
            <mvc:exclude-mapping path="/**.ico"/>
            
            <mvc:exclude-mapping path="/resources/**"/>
            <bean class="com.ql.restful.interceptor.MyInterceptor"/>
        mvc:interceptor>
    mvc:interceptors>
1
2
3
4
5
6
7
8
9
10
11
12
13
14

运行工程，在浏览器地址栏中输入http://localhost:8080/restful/persons，控制台中会输出

多Interceptor执行顺序

有多个拦截器时按照配置的顺序依次访问执行。

在com.ql.restful.interceptor目录下再创建一个拦截器MyInterceptor1

package com.ql.restful.interceptor;

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

public class MyInterceptor1 implements HandlerInterceptor {
    @Override
    public boolean preHandle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler) throws Exception {
        System.out.println(request.getRequestURL()+"准备执行1");
        return true;
    }

    @Override
    public void postHandle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println(request.getRequestURL()+"-目标处理成功1");
    }

    @Override
    public void afterCompletion(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println(request.getRequestURL()+"-响应内容已产生1");
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23

然后在applicationContext.xml中配置拦截器

    <mvc:interceptors>
        <mvc:interceptor>
            
            
            <mvc:mapping path="/restful/**"/>
            
            <mvc:exclude-mapping path="/**.js"/>
            <mvc:exclude-mapping path="/**.css"/>
            <mvc:exclude-mapping path="/**.ico"/>
            
            <mvc:exclude-mapping path="/resources/**"/>
            <bean class="com.ql.restful.interceptor.MyInterceptor"/>
        mvc:interceptor>
    mvc:interceptors>

    <mvc:interceptors>
        <mvc:interceptor>
            
            
            <mvc:mapping path="/restful/**"/>
            
            <mvc:exclude-mapping path="/**.js"/>
            <mvc:exclude-mapping path="/**.css"/>
            <mvc:exclude-mapping path="/**.ico"/>
            
            <mvc:exclude-mapping path="/resources/**"/>
            <bean class="com.ql.restful.interceptor.MyInterceptor1"/>
        mvc:interceptor>
    mvc:interceptors>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

运行工程，在浏览器中访问http://localhost:8080/restful/persons控制台输出为

preHandle返回值

拦截器中preHandle方法返回boolean值，返回true则请求依次向后传递，如果返回false请求会被中断。

修改com.ql.restful.interceptor包下的MyInterceptor拦截器

package com.ql.restful.interceptor;

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

public class MyInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler) throws Exception {
        System.out.println(request.getRequestURL()+"准备执行");
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().print("请求被拦截");
        return false;
    }

    @Override
    public void postHandle(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println(request.getRequestURL()+"-目标处理成功");
    }

    @Override
    public void afterCompletion(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println(request.getRequestURL()+"-响应内容已产生");
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

运行项目浏览器中访问http://localhost:8080/restful/persons响应结果为

控制台中也只输出了preHandle中的打印语句内容。