如何定义SpringMVC框架拦截器呢？

SpringMVC 中的 Interceptor 拦截器也是相当重要和相当有用的，它的主要作用是拦截用户的请求并进行相应的处理。比如通过它来进行权限验证，或者是来判断用户是否登陆等操作。

SpringMVC 拦截器的定义方式

实现接口
继承适配器

案例实操

实现接口

实现 HandlerInterceptor 接口方式定义我们的拦截器代码如下:

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n13" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public class MyInterceptor implements HandlerInterceptor{

/**

preHandle 在请求方法拦截前执行
返回 true 代表对当前请求进行放行处理

/

@Override

public boolean preHandle(HttpServletRequest request,

HttpServletResponse response, Object handler) throws Exception {

System.out.println("action 之前执行！！！");

return true; //继续执行 action

}

/*
请求执行后，生成视图前执行

/

@Override

public void postHandle(HttpServletRequest request,

HttpServletResponse response, Object handler,

ModelAndView modelAndView) throws Exception {

System.out.println("Action 执行之后，生成视图之前执行！！");

}

/*
在请求方法执行后进行拦截

*/

@Override

public void afterCompletion(HttpServletRequest request,

HttpServletResponse response, Object handler, Exception ex)

throws Exception {

System.out.println("方法执行后进行拦截。。释放资源。。。");

}

} </pre>

对应配置有两种方式:

配置方式一（拦截所有请求配置方式）：

配置方式二（拦截指定请求配置方式）

mvc:interceptors

效果：

请求地址: http://localhost:8080/springmvc03/test/hello.do

控制台打印结果信息：

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多个拦截器配置（多个拦截器组成一个拦截器链，栈式结构 123 321 退出）：

继承适配器

继承 HandlerInterceptorAdapter 方式定义拦截器（实际上最终还是 HandlerInterceptor 接口实现）

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n34" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public class MyInterceptor2 extends HandlerInterceptorAdapter{

/**

重写 preHandle 请求执行前执行
*/

@Override

public boolean preHandle(HttpServletRequest request,

HttpServletResponse response, Object handler) throws Exception {

System.out.println("请求前执行。。。");

return true;

}

} </pre>

扩展

使用拦截器完成用户是否登录请求验证拦截器定义:

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n39" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public class LoginInterceptor implements HandlerInterceptor{

/**

方法拦截前执行

/

@Override

public boolean preHandle(HttpServletRequest request,

HttpServletResponse response, Object handler) throws Exception {

User user= (User) request.getSession().getAttribute("user");

/*
判断 uri 是否包含路径
包含就放行

/

if(request.getRequestURI().indexOf("userLogin.do")>-1){

return true;

}

/*
判断 session user 是否为空

/

if(null==user){

response.sendRedirect(request.getContextPath()+"/login.jsp");

return false;

}

return true; //继续执行 action

}

@Override

public void postHandle(HttpServletRequest request,

HttpServletResponse response, Object handler,

ModelAndView modelAndView) throws Exception {

System.out.println("Action 执行之后，生成视图之前执行！！");

}

/*
在方法执行后进行拦截

*/

@Override

public void afterCompletion(HttpServletRequest request,

HttpServletResponse response, Object handler, Exception ex)

throws Exception {

System.out.println("方法执行后进行拦截。。释放资源。。。");

}

} </pre>

UserController 类

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n42" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">/**

*

* @author Administrator

* 模拟用户操作

*/

@Controller

@RequestMapping("/user")

public class UserLoginController {

@RequestMapping("/userLogin")

public ModelAndView userLogin(HttpServletRequest request){

ModelAndView mv=new ModelAndView();

User user=new User();

user.setUserName("xxx");

user.setUserPwd("123456");

request.getSession().setAttribute("user", user);

mv.setViewName("success");

return mv;

}

@RequestMapping("/addUser")

public ModelAndView addUser(){

System.out.println("添加用户记录。。。");

ModelAndView mv=new ModelAndView();

mv.setViewName("success");

return mv;

}

@RequestMapping("/delUser")

public ModelAndView delUser(){

ModelAndView mv=new ModelAndView();

mv.setViewName("success");

return mv;

}

@RequestMapping("/updateUser")

public ModelAndView updateUser(){

ModelAndView mv=new ModelAndView();

mv.setViewName("success");

return mv;

}
} </pre>

拦截器 xml 配置

如何定义SpringMVC框架拦截器呢？