Spring MVC 使用拦截器优雅地实现权限验证功能

在上一篇 SpringAOP 实现功能权限校验功能 中虽然用AOP通过抛异常,请求转发等勉强地实现了权限验证功能,但感觉不是那么完美,应该用拦截器来实现才是最佳的,因为拦截器就是用来拦截请求的,在请求层面进行权限验证是最好的时机。

假设下面的请求需要进行权限验证,在请求中通过参数params指定必须带有Helper.PARAM_FUNCTION_ID参数,这样拦截器通过判断是否带有该参数,如果带有则进行权限验证,否则不作处理。

@RequestMapping(value = "/moduleAccess.do",params=Helper.PARAM_FUNCTION_ID, method = RequestMethod.POST, produces="text/html;charset=utf-8")
@ResponseBody
public String moduleAccess(String action,FrmModule module) {
int rs = -1;
try{
if(Helper.F_ACTION_CREATE.equals(action)){
rs = moduleService.access(module,Helper.DB_ACTION_INSERT);
//module.setModuleid(rs);
module = moduleService.selectByPrimaryKey(rs);
}else if(Helper.F_ACTION_EDIT.equals(action)){
rs = moduleService.access(module,Helper.DB_ACTION_UPDATE);
module = moduleService.selectByPrimaryKey(module.getModuleid());
}else if(Helper.F_ACTION_REMOVE.equals(action)){
rs = moduleService.access(module,Helper.DB_ACTION_DELETE);
}else{
return JSON.toJSONString(new Result(false,"请求参数错误:action"));
}
}catch(Exception e){
e.printStackTrace();
return JSON.toJSONString(new Result(false,"操作失败,出现异常,请联系管理员!"));
}
if(rs<0){
return JSON.toJSONString(new Result(false,"操作失败,请联系管理员!"));
}
return JSON.toJSONString(new Result(true,module));
}

那么对应的拦截器就直接用登录验证的那个拦截器即可,SecurityInterceptor

package com.jykj.demo.filter;

import java.io.PrintWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView; import com.alibaba.fastjson.JSON;
import com.jykj.demo.entity.SysUser;
import com.jykj.demo.service.SysUserRolePermService;
import com.jykj.demo.util.Helper;
import com.jykj.demo.util.Result;
/**
* 1.此拦截器用于拦截所有请求,用于登录权限验证
* 2.拦截 带 moduleId 参数的请求,在渲染视图之前返回 模块权限值
* @author Administrator
*
*/
public class SecurityInterceptor implements HandlerInterceptor{
@Autowired
SysUserRolePermService sysUserRolePermService;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
System.out.println("SecurityInterceptor preHandle:"+request.getContextPath()+","+request.getRequestURI()+","+request.getMethod());
HttpSession session = request.getSession();
if (session.getAttribute(Helper.SESSION_USER) == null) {
System.out.println("AuthorizationException:未登录!"+request.getMethod());
if("POST".equalsIgnoreCase(request.getMethod())){
response.setContentType("text/html; charset=utf-8");
PrintWriter out = response.getWriter();
out.write(JSON.toJSONString(new Result(false,"未登录!")));
out.flush();
out.close();
}else{
response.sendRedirect(request.getContextPath()+"/login");
}
return false;
} else {
Object obj = request.getParameter(Helper.PARAM_FUNCTION_ID);
if(obj==null) return true;//没有带功能参数不需要验证
int functionId = Integer.parseInt(obj.toString());
String rs = sysUserRolePermService.permissionValidate(functionId);
System.out.println("校验结果:"+rs);
if(rs.trim().isEmpty()){
return true;//正常通过
}else{
response.setContentType("text/html; charset=utf-8");
PrintWriter out = response.getWriter();
out.write(JSON.toJSONString(new Result(false,rs)));
out.flush();
out.close();
return false;
}
}
}
//模块权限值
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
/*
Object obj = request.getParameter(Helper.PARAM_MODULE_ID);
System.out.println(Helper.PARAM_MODULE_ID+":"+obj);
if(obj == null) return;//如果没有moduleId 参数,否则什么都不做,否则返回模块权限值
System.out.println("SecurityInterceptor postHandle:"+request.getContextPath()+","+request.getRequestURI()+","+request.getMethod());
SysUser loginUser = (SysUser)request.getSession().getAttribute(Helper.SESSION_USER);
int value = sysUserRolePermService.getModulePerm(loginUser.getUserid(),Integer.parseInt(obj.toString()));
modelAndView.addObject(Helper.MVALUE,value);
*/
} @Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception { } }

拦截器配置不变

 <mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/*"/> <!-- 拦截/ /test /login 等等单层结构的请求 -->
<mvc:mapping path="/**/*.aspx"/><!-- 拦截后缀为.aspx的请求 -->
<mvc:mapping path="/**/*.do"/><!-- 拦截后缀为 .do的请求 -->
<mvc:exclude-mapping path="/login"/>
<mvc:exclude-mapping path="/signIn"/>
<mvc:exclude-mapping path="/register"/>
<bean class="com.jykj.demo.filter.SecurityInterceptor">
</bean>
</mvc:interceptor>
</mvc:interceptors>

这样即实现了对某个功能的权限校验的功能 
客户端发送 /moduleAccess.do 请求,该请求带有参数Helper.PARAM_FUNCTION_ID,其值为某个功能的id 
然后拦截器拦截该请求,判断出带有该参数,则对其进行权限校验,如果未通过,写response给客户端,格式是json的字符串,并返回false表示请求已由本拦截器处理了,不会往下执行(返回true表示正常往下执行)。这样就达到了权限验证的目的。这是相对更优雅的实现方式,最起码比上一篇讲的用AOP来实现更优雅。

另外拦截器的postHandle方法是在控制器执行结束,页面渲染之前执行的,所以可以用来给页面添加或修改model属性。

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