从零开始搭建自己的网站六：拦截器添加

因为管理台是需要账号密码才能登录的，所以我们就增加相应的拦截器，防止用户直接通过url直接进入管理台页面。

1、首先对上篇文章中的用户登录验证方法进行修改。"redirect:/manager/index" 意思是重定向到 /manager/index。

/**
* 用户登录验证
*/
@RequestMapping("/loginUser")
public String loginUser(HttpServletRequest request, String username, String password) {
if (StringUtils.isNotBlank(username) && StringUtils.isNotBlank(password)) {
boolean login = userService.login(username, password);
if (login) {
request.getSession().setAttribute("user", username);
return "redirect:/manager/index";
}
}
return "manager/login";
}

2、在Application中加入拦截器配置：登录拦截器和全局拦截器。登录拦截器只对/manager/下的url地址拦截。全局拦截器拦截全局的页面。

@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new LoginInterceptor()).addPathPatterns("/manager/*");
registry.addInterceptor(new MainInterceptor()).addPathPatterns("/*");
super.addInterceptors(registry);
}

3、编写拦截器。登录拦截器验证的是否session中存在user，不存在就跳转到登录页面。全局拦截器是检查url是否存在，不存在就重定向到404页面。

public class LoginInterceptor implements HandlerInterceptor {

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
String user = (String) request.getSession().getAttribute("user");
if (StringUtils.isNotBlank(user)) {
return true;
} else {
response.sendRedirect("/login/index");
return false;
}
}

@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

}

@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

}
}

public class MainInterceptor implements HandlerInterceptor {

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
int status = response.getStatus();
if (status == 404) {
response.sendRedirect("/404");
return false;
} else {
return true;
}
}

@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

}

@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

}
}

4、配置完之后，先不登录，直接浏览器进入 http://localhost:8088/manager/index，页面就会跳转到登录页面。拦截器配置完成
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如果文章中有任何问题或者可以改进的地方，请大家多提提意见，我会非常感激。