Spring MVC 拦截器实现

示例【用户登录才能访问主页】

创建User

package com.po;
public class User {
	private String userName;
	private String passWord;
	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;
	}
}

创建UserController

package com.controller;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import com.po.User;
@Controller
public class UserController {
	//跳转到登录页面
	@RequestMapping("/loginForm")
	public String loginForm() {
		return "loginForm";
	}
	//用户登录
	@RequestMapping("/login")
	public String login(@ModelAttribute User user,HttpSession session) {
		if(user.getUserName().equals("admin")&&user.getPassWord().equals("admin123")) {
			session.setAttribute("user", user);
			return "redirect:main";
		}else {
			return "loginForm";
		}
	}
	//跳转到主页面
	@RequestMapping("/main")
	public String main() {
		return "success";
	}
}

创建UserLoginInterceptor

package com.interceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import com.po.User;
//拦截器必须实现HandlerInterceptor接口
public class UserLoginInterceptor implements HandlerInterceptor{
	/**
	 * 该方法将在整个请求完成之后执行， 主要作用是用于清理资源的，
	 * 该方法也只能在当前Interceptor的preHandle方法的返回值为true时才会执行。  
	 */
	@Override
	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
			throws Exception {
		System.out.println("UserLoginInterceptor->afterCompletion()");		
	}
	/** 
	  * 该方法将在Controller的方法调用之后执行， 方法中可以对ModelAndView进行操作 ，
	 * 该方法也只能在当前Interceptor的preHandle方法的返回值为true时才会执行。 
     */
	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView arg3)
			throws Exception {
		System.out.println("UserLoginInterceptor->postHandle()");
	}
	/** 
	 * preHandle方法是进行处理器拦截用的，该方法将在Controller处理之前进行调用，
	   * 该方法的返回值为true拦截器才会继续往下执行，该方法的返回值为false的时候整个请求就结束了。 
     */
	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
		System.out.println("UserLoginInterceptor->preHandle");
		// 不拦截"/loginForm"和"/login"请求
		String url[]= {"/loginForm", "/login"};
		String servletPath=request.getServletPath();
		//获取请求的路径进行判断
		for(String str:url) {
			if(servletPath.contains(str)) {
				return true;
			}
		}
		User user=(User) request.getSession().getAttribute("user");
		if(user==null) {
			request.setAttribute("msg", "请先登录再访问本站");
			request.getRequestDispatcher("loginForm").forward(request, response);
		}
		return true;
	}
	
}

配置springmvc-config.xml

<!-- 使用注解驱动 -->
<mvc:annotation-driven />
<!-- 定义扫描的包 -->
<context:component-scan base-package="com.*" />
<mvc:resources location="/images/" mapping="/images/**"/>
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
	<property name="prefix" value="/WEB-INF/view/"></property>
	<property name="suffix" value=".jsp" />
</bean>
<mvc:interceptors>
	<mvc:interceptor>
		<mvc:mapping path="/*"/>
		<bean class="com.interceptor.UserLoginInterceptor"></bean>
	</mvc:interceptor>
</mvc:interceptors>

创建loginForm.jsp

<h3>用户登录</h3>
	${msg }
	<form action="login" method="post">
	<table>
		<tr>
			<td>用户名：</td>
			<td><input type="text" name="userName"></td>
		</tr>
		<tr>
			<td>密码：</td>
			<td><input type="password" name="passWord"></td>
		</tr>
		<tr>
			<td></td>
			<td><input type="submit" value="登录"></td>
		</tr>
	</table>
	</form>

创建success.jsp

<a>首页</a>|<a>订单</a>|<a>购物车</a>|<a>登录</a>|<a>注册</a>
	<p>
	<table width="300px" border="1">
		<tr>
			<th>序号</th>
			<th>名称</th>
			<th>图片</th>
		</tr>
		<tr>
			<td>1</td>
			<td>iPhone X</td>
			<td><img src="images/iPhone X.jpg" height="50px"></td>
		</tr>
		<tr>
			<td>2</td>
			<td>vivo_nex</td>
			<td><img src="images/vivo_nex.jpg" height="50px"></td>
		</tr>
	</table>

启动Tomcat访问：http://localhost:8080/jackson/main

输入正确用户、密码之后