SpringMVC中的拦截器详解及代码示例

//测试拦截器1
public class HandlerInterceptor1 implements HandlerInterceptor{
	@Override
	  public Boolean preHandle(HttpServletRequest request,
	      HttpServletResponse response, Object handler) throws Exception {
		System.out.println("HandlerInterceptor1....preHandle");
		//false表示拦截，不向下执行；true表示放行
		return true;
	}
	@Override
	  public void postHandle(HttpServletRequest request,
	      HttpServletResponse response, Object handler,
	      ModelAndView modelAndView) throws Exception {
		System.out.println("HandlerInterceptor1....postHandle");
	}
	@Override
	  public void afterCompletion(HttpServletRequest request,
	      HttpServletResponse response, Object handler, Exception ex)
	      throws Exception {
		System.out.println("HandlerInterceptor1....afterCompletion");
	}
}

<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping">
  <property name="interceptors">
    <list>
      <ref bean="handlerInterceptor1"/>
      <ref bean="handlerInterceptor2"/>
    </list>
  </property>
</bean>
<bean id="handlerInterceptor1" class="ssm.intercapter.HandlerInterceptor1"/>
<bean id="handlerInterceptor2" class="ssm.intercapter.HandlerInterceptor2"/>

<!-- 配置拦截器 -->
<mvc:interceptors>
  <!-- 多个拦截器，按顺序执行 -->    
  <mvc:interceptor>
    <mvc:mapping path="/**"/> <!-- 表示拦截所有的url包括子url路径 -->
    <bean class="ssm.interceptor.HandlerInterceptor1"/>
  </mvc:interceptor>
  <mvc:interceptor>
    <mvc:mapping path="/**"/>
    <bean class="ssm.interceptor.HandlerInterceptor2"/>
  </mvc:interceptor>
  <mvc:interceptor>
    <mvc:mapping path="/**"/>
    <bean class="ssm.interceptor.HandlerInterceptor3"/>
  </mvc:interceptor>
</mvc:interceptors>

//登陆
@RequestMapping("/login")
public String login(HttpServletRequest request, String username, String password) throws Exception {
	//实际中要去和数据库匹配的
	//....
	//这里就假设登陆成功了
	HttpSession session = request.getSession();
	session.setAttribute("username", username);
	return "redirect:queryItems.action";
}
//退出
@RequestMapping("/logout")
public String logout(HttpServletRequest request) throws Exception {
	HttpSession session = request.getSession();
	session.invalidate();
	return "redirect:queryItems.action";
}

//测试拦截器1
public class LoginInterceptor implements HandlerInterceptor{
	//进入Handler方法之前执行
	//可以用于身份认证、身份授权。如果认证没有通过表示用户没有登陆，需要此方法拦截不再往下执行，否则就放行
	@Override
	  public Boolean preHandle(HttpServletRequest request,
	      HttpServletResponse response, Object handler) throws Exception {
		//获取请求的url
		String url = request.getRequestURI();
		//判断url是否公开地址（实际使用时将公开地址配置到配置文件中）
		//这里假设公开地址是否登陆提交的地址
		if(url.indexOf("login.action") > 0) {
			//如果进行登陆提交，放行
			return true;
		}
		//判断session
		HttpSession session = request.getSession();
		//从session中取出用户身份信息
		String username = (String) session.getAttribute("username");
		if(username != null) {
			return true;
		}
		//执行到这里表示用户身份需要验证，跳转到登陆页面
		request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
		return false;
	}
	//节省空间，省略另外两个方法不写了，也不用处理
}

<!-- 配置拦截器 -->
<mvc:interceptors>
  <!-- 多个拦截器，按顺序执行 -->  
  <mvc:interceptor>
    <mvc:mapping path="/**"/> <!-- 拦截所有的url包括子url路径 -->
    <bean class="ssm.interceptor.LoginInterceptor"/>
  </mvc:interceptor>
  <!-- 其他拦截器 -->
</mvc:interceptors>

<form action="${pageContext.request.contextPath }/login.action" method="post">
  用户名：<input type="text" name="username" /><br>
  密码：<input type="password" name="password" /><br>
  <input type="submit" name="提交" />
</form>