一. Interceptor
首先编写一个拦截器，编辑器需要添加@Component注解，并实现HandlerInterceptor 接口，然后重写preHandle、postHandle、afterCompletion，其中：
-
preHandle：在请求目标请求之前执行，返回值如果为true，则代表放行，如果为false，则代表为拦截
-
postHandle：请求目标请求之后执行，返回视图之前
-
afterCompletion：请求完成时执行
package io.zhangjia.springmvc.interceptors;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@Component
public class Interceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("Interceptor.preHandle");
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("Interceptor.postHandle");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("Interceptor.afterCompletion");
}
}
接下来在spring-mvc.xml中配置拦截器：
<mvc:interceptors> <ref bean="interceptor" /> </mvc:interceptors>
ref的bean属性的值即为我们的拦截器类的类名小写（因为添加了@Component注解，则其id默认为类名小写）
最后编写Controller和jsp：
@Controller
public class Test {
@RequestMapping("/test")
public String testInterceptor(String name,Model model) {
System.out.println("Test.testInterceptor");
model.addAttribute("result",name);
return "test";
}
}
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" %>
<!DOCTYPE html>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>你好</h1>
<h1>${requestScope.result}</h1>
</body>
</html>
当我们访问http://localhost:8888/sm/test?name=张甲时，控制台输出：
Interceptor.preHandle Test.testInterceptor Interceptor.postHandle Interceptor.afterCompletion
如果我们将preHandle的返回值修改为false，即拦截， 则控制台输出：
Interceptor.preHandle
二. 总结
1. 配置拦截器
-
添加@Component注解，并实现HandlerInterceptor 接口
2. 配置spring-mvc.xm
<mvc:interceptors> <ref bean="interceptor" /> </mvc:interceptors>
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