Java SpringBoot 使用拦截器作为权限控制

如何实现

首先拦截器是属于web这块的，那我们需要引入springboot web模块，具体版本在parent中

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

然后我们在config目录下新建interceptor目录，用来放拦截器

• 我们新建两个拦截器，一个用来登陆拦截，一个用来进行管理员拦截。
• 登陆拦截不必多说，就是判断除登陆请求外所有请求是否登陆过，没有我们就截断请求，然会返回失败状态
• 管理员拦截，拦截的是管理员才能访问的资源，比如用户管理/权限管理等，它是登陆拦截放行后才能进行的，
  就像关卡是一关一关的。登陆验证后进入管理员验证，判断该登陆用户是否具有管理员权限，若拥有则放行，否则拦截并返回失败状态
• 拦截器的核心是实现 org.springframework.web.servlet.HandlerInterceptor 接口，验证逻辑一般写在 preHandle 方法中，在请求资源前
• 我的验证逻辑比较简单，登陆验证就是从session中取出用户信息，判断是否存在，用户信息是登陆成功时放入session中的，大家也可以使用JWT验证
• 管理员验证也是从session中取出管理员信息，判断是否是管理员，管理员信息是登陆成功时将是否是管理员的信息放入session中的，大家也可以使用JWT验证

登陆拦截器

package com.example.interceptor_demo.config.interceptor;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
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;
import javax.servlet.http.HttpSession;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;
/**
 * 拦截器，登录检查
 */
@Component
public class LoginInterceptor implements HandlerInterceptor {

    @Autowired
    private HttpSession session;

    @Autowired
    private ObjectMapper objectMapper;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        Object user = session.getAttribute("sessionUser");
        if (sessionUser!=null){
            return true;
        }else {
            Map<String,Object> notLogin = new HashMap<>();
            notLogin.put("msg","not login");
            notLogin.put("code",403);
            notLogin.put("data",null);
            try(PrintWriter printWriter = response.getWriter()){
                printWriter.print(objectMapper.writeValueAsString(notLogin));
            }catch (Exception e){
                e.printStackTrace();
            }
            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 {
    }

}

管理员拦截器

package com.example.interceptor_demo.config.interceptor;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
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;
import javax.servlet.http.HttpSession;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;
/**
 * 拦截器，管理员验证
 */
@Component
public class AdminInterceptor implements HandlerInterceptor {

    @Autowired
    private HttpSession session;

    @Autowired
    private ObjectMapper objectMapper;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        Boolean isAdmin = (Boolean)session.getAttribute("sessionAdmin");
        if (isAdmin!=null && isAdmin){
            return true;
        }else {
            Map<String,Object> notLogin = new HashMap<>();
            notLogin.put("msg","no power");
            notLogin.put("code",403);
            notLogin.put("data",null);
            try(PrintWriter printWriter = response.getWriter()){
                printWriter.print(objectMapper.writeValueAsString(notLogin));
            }catch (Exception e){
                e.printStackTrace();
            }
            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 {
    }

}

最后我们在config目录下新建WebMvcConfig类，用来注册拦截器

• 拦截器注册类的核心是实现 org.springframework.web.servlet.config.annotation.WebMvcConfigurer 接口
• 实现 addInterceptors 方法，参数 registry 对象可用来注册拦截器
• registry.addInterceptor() 方法用来添加拦截器
• .addPathPatterns() 方法是为该拦截器添加拦截资源路径
• .excludePathPatterns() 方法是为该拦截器添加要放行的资源路径
• 其中 * 代表路径下任意名称，** 代表任意路径下任意名称

package com.example.interceptor_demo.config;

import com.example.interceptor_demo.config.interceptor.AdminInterceptor;
import com.example.interceptor_demo.config.interceptor.LoginInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Autowired
    private LoginInterceptor loginInterceptor;

    @Autowired
    private AdminInterceptor adminInterceptor;
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        this.loginInterceptor(registry);//登录拦截        
        this.adminInterceptor(registry);//管理员拦截
    }

    private void loginInterceptor(InterceptorRegistry registry){
        registry.addInterceptor(loginInterceptor)
                .addPathPatterns("/**")
                .excludePathPatterns(//释放登陆接口
                        "/login/**"
                );
    }

    private void adminInterceptor(InterceptorRegistry registry){
        registry.addInterceptor(htmlPageInterceptor)
                .addPathPatterns("/admin/**");//拦截管理员接口
    }
}