文章目录
1 拦截器概述1.1 拦截器的定义1.2 拦截器的配置
2 拦截器的执行流程2.1 单个拦截器执行顺序2.1.1 举个例子
2.2 多个拦截器执行顺序2.2.1 举个例子
3 应用案例-实现用户登录权限验证3.1 案例说明3.2 流程图3.3 实现代码3.3.1 User.java3.3.2 UserController.java3.3.3 LoginInterceptor.java3.3.4 配置拦截器（springmvc-config.xml）3.3.5 login.jsp3.3.6 main.jsp
3.4 测试结果
1 拦截器概述
Spring MVC中的拦截器（Interceptor）类似于Servlet中的过滤器（Filter），主要用于拦截用户请求并作相应的处理。拦截器可以进行全限验证、记录请求信息的日志、判断用户是否登录等。
1.1 拦截器的定义
通过实现HandlerInterceptor接口，或者继承HandlerInterceptor接口的实现类（如HandlerInterceptorAdapter）来定义。通过实现WebRequestInterceptor接口，或者继承WebRequestInterceptor接口的实现类来定义。
以实现HandlerInterceptor接口方式为例：
1.2 拦截器的配置
在Spring MVC的配置文件中进行配置：
2 拦截器的执行流程
在程序运行过程中，拦截器的执行是由顺序的，这个顺序和拦截器的定义顺序有关。
2.1 单个拦截器执行顺序
2.1.1 举个例子
springmvc-config.xml中配置拦截器
<mvc:interceptors>
<bean class="cn.edu.ujn.ch15.interceptor.CustomerInterceptor"></bean>
</mvc:interceptors>
HelloController.java
package cn
.edu
.ujn
.ch15
.controller
;
import org
.springframework
.stereotype
.Controller
;
import org
.springframework
.web
.bind
.annotation
.RequestMapping
;
@Controller
public class HelloController {
@RequestMapping("/hello")
public String
hello() {
System
.out
.println("hello!");
return "success";
}
@RequestMapping("/find")
public String
find() {
System
.out
.println("Find!");
return "success";
}
}
CustomerInterceptor.java
package cn
.edu
.ujn
.ch15
.interceptor
;
import javax
.servlet
.http
.HttpServletRequest
;
import javax
.servlet
.http
.HttpServletResponse
;
import org
.springframework
.web
.servlet
.HandlerInterceptor
;
import org
.springframework
.web
.servlet
.ModelAndView
;
public class CustomerInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
)
throws Exception
{
System
.out
.println("CustomerInterceptor--preHandle");
return true;
}
public void postHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
,
ModelAndView modelAndView
) throws Exception
{
System
.out
.println("CustomerInterceptor--postHandle");
}
public void afterCompletion(HttpServletRequest request
, HttpServletResponse response
, Object handler
, Exception ex
)
throws Exception
{
System
.out
.println("CustomerInterceptor--afterCompletion");
}
}
测试结果：
2.2 多个拦截器执行顺序
2.2.1 举个例子
springmvc-config.xml中配置拦截器：
<mvc:interceptors>
<bean class="cn.edu.ujn.ch15.interceptor.CustomerInterceptor"></bean>
<mvc:interceptor>
<mvc:mapping path="/hello" />
<bean class="cn.edu.ujn.ch15.interceptor.Interceptor2"></bean>
</mvc:interceptor>
</mvc:interceptors>
HelloController.java
package cn
.edu
.ujn
.ch15
.controller
;
import org
.springframework
.stereotype
.Controller
;
import org
.springframework
.web
.bind
.annotation
.RequestMapping
;
@Controller
public class HelloController {
@RequestMapping("/hello")
public String
hello() {
System
.out
.println("hello!");
return "success";
}
@RequestMapping("/find")
public String
find() {
System
.out
.println("Find!");
return "success";
}
}
拦截器1（CustomerInterceptor.java）
package cn
.edu
.ujn
.ch15
.interceptor
;
import javax
.servlet
.http
.HttpServletRequest
;
import javax
.servlet
.http
.HttpServletResponse
;
import org
.springframework
.web
.servlet
.HandlerInterceptor
;
import org
.springframework
.web
.servlet
.ModelAndView
;
public class CustomerInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
)
throws Exception
{
System
.out
.println("CustomerInterceptor--preHandle");
return true;
}
public void postHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
,
ModelAndView modelAndView
) throws Exception
{
System
.out
.println("CustomerInterceptor--postHandle");
}
public void afterCompletion(HttpServletRequest request
, HttpServletResponse response
, Object handler
, Exception ex
)
throws Exception
{
System
.out
.println("CustomerInterceptor--afterCompletion");
}
}
拦截器2（Interceptor2.java）
package cn
.edu
.ujn
.ch15
.interceptor
;
import javax
.servlet
.http
.HttpServletRequest
;
import javax
.servlet
.http
.HttpServletResponse
;
import org
.springframework
.web
.servlet
.HandlerInterceptor
;
import org
.springframework
.web
.servlet
.ModelAndView
;
public class Interceptor2 implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
)
throws Exception
{
System
.out
.println("Interceptor2--preHandle");
return true;
}
public void postHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
,
ModelAndView modelAndView
) throws Exception
{
System
.out
.println("Interceptor2--postHandle");
}
public void afterCompletion(HttpServletRequest request
, HttpServletResponse response
, Object handler
, Exception ex
)
throws Exception
{
System
.out
.println("Interceptor2--afterCompletion");
}
}
测试结果
3 应用案例-实现用户登录权限验证
3.1 案例说明
登录验证：只有登录成功后的用户才可以访问系统中的主页面未登录：拦截器会将请求拦截，并转发到登录页面，同时在登录页面中给出提示信息登录未成功：在登录页面给出相应的提示信息退出登录：系统同样会回到登录页面
3.2 流程图
3.3 实现代码
3.3.1 User.java
package cn
.edu
.ujn
.ch15
.model
;
public class User {
private int id
;
private String username
;
private String password
;
public int getId() {
return id
;
}
public void setId(int id
) {
this.id
= id
;
}
public String
getUsername() {
return username
;
}
public void setUsername(String username
) {
this.username
= username
;
}
public String
getPassword() {
return password
;
}
public void setPassword(String password
) {
this.password
= password
;
}
@Override
public String
toString() {
return "User [id=" + id
+ ", username=" + username
+ ", password=" + password
+ "]";
}
}
3.3.2 UserController.java
package cn
.edu
.ujn
.ch15
.controller
;
import javax
.servlet
.http
.HttpSession
;
import org
.springframework
.stereotype
.Controller
;
import org
.springframework
.ui
.Model
;
import org
.springframework
.web
.bind
.annotation
.RequestMapping
;
import org
.springframework
.web
.bind
.annotation
.RequestMethod
;
import cn
.edu
.ujn
.ch15
.model
.User
;
@Controller
public class UserController {
@RequestMapping(value
= "/login", method
= RequestMethod
.GET
)
public String
toLogin() {
return "login";
}
@RequestMapping(value
= "/login", method
= RequestMethod
.POST
)
public String
login(User user
, Model model
, HttpSession session
) {
if ("A".equals(user
.getUsername())) {
session
.setAttribute("USER_SESSION", user
);
return "redirect:main";
}
model
.addAttribute("msg", "用户名或密码错误，请重新登录！");
return "login";
}
@RequestMapping("/main")
public String
toMain() {
return "main";
}
@RequestMapping("/logout")
public String
logout(HttpSession session
) {
session
.invalidate();
return "redirect:login";
}
}
3.3.3 LoginInterceptor.java
package cn
.edu
.ujn
.ch15
.interceptor
;
import javax
.servlet
.http
.HttpServletRequest
;
import javax
.servlet
.http
.HttpServletResponse
;
import javax
.servlet
.http
.HttpSession
;
import org
.springframework
.web
.servlet
.HandlerInterceptor
;
import cn
.edu
.ujn
.ch15
.model
.User
;
public class LoginInterceptor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request
, HttpServletResponse response
, Object handler
)
throws Exception
{
String url
= request
.getRequestURI();
if (url
.indexOf("/login") >= 0)
return true;
HttpSession session
= request
.getSession();
User user
= (User
) session
.getAttribute("USER_SESSION");
if (user
!= null
)
return true;
request
.setAttribute("msg", "被拦截，您还没有登录，不能访问页面！");
request
.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request
, response
);
return false;
}
}
3.3.4 配置拦截器（springmvc-config.xml）
<mvc:interceptor>
<mvc:mapping path="/**" />
<bean class="cn.edu.ujn.ch15.interceptor.LoginInterceptor"></bean>
</mvc:interceptor>
3.3.5 login.jsp
<%@ page language
="java" contentType
="text/html; charset=UTF-8"
pageEncoding
="UTF-8"%>
<%@ page isELIgnored
="false" %>
<html>
<head>
<meta http
-equiv
="Content-Type" content
="text/html; charset=UTF-8">
<title>用户登录
</title
>
</head
>
<body>
$
{msg
}
<form action
="${pageContext.request.contextPath }/login"
method
="POST">
用户名：
<input type
="text" name
="username"/><br
/>
密
 
; 
; 
;码：
<input type
="password" name
="password"/><br
/>
<input type
="submit" value
="登录" />
</form
>
</body
>
</html
>
3.3.6 main.jsp
<%@ page language
="java" contentType
="text/html; charset=UTF-8"
pageEncoding
="UTF-8"%>
<%@ page isELIgnored
="false" %>
<html>
<head>
<meta http
-equiv
="Content-Type" content
="text/html; charset=UTF-8">
<title>系统主页
</title
>
</head
>
<body>
当前用户：$
{USER_SESSION
.username
}
<a href
="${pageContext.request.contextPath }/logout">退出
</a
>
</body
>
</html
>
3.4 测试结果
登录不成功，无法访问main.jsp页面
登录成功
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