一文解决在SpringBoot项目中配置拦截器

一、实现的功能

类似于下面功能的拦截器

自定义拦截器的步骤
    第一步：自定义一个实现了Interceptor接口的类，或者继承抽象类AbstractInterceptor。
    第二步：在配置文件中注册定义的拦截器。
    第三步：在需要使用Action中引用上述定义的拦截器，为了方便也可以将拦截器定义为默认的拦截器，这样在不加特殊说明的情况下，所有的
Action都被这个拦截器拦截。

二、写我们的项目功能

controller层

UserController.java

@RestController
@RequestMapping("user")
public class UserController {
    @Autowired
    private UserService userService;

    @Autowired
    private HttpSession session;
    @RequestMapping(value = "login")
    public Map<String,Object> login(User user){
        Map<String,Object> map = new HashMap<>();
        map.put("code",0);
        if(StringUtils.isEmpty(user.getUsername()) || StringUtils.isEmpty(user.getPassword()) ){
            map.put("msg","用户或者密码为空！");
            return map;
        }
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("username",user.getUsername())
                .eq("password",user.getPassword());
        User userDb = userService.getOne(queryWrapper);
        if(userDb != null){
            map.put("code",1);
            map.put("data",userDb);
            session.setAttribute("username",userDb.getUsername());
        }else{
            map.put("msg","用户名或密码错误！");
        }
        return map;
    }
}

UserService.java

public interface UserService extends IService<User> {
    List<User> findAll();

    void transfer();

    List<User> listUser(String username);
    List<User> listUser(String username,String password);
}

UserServiceImpl.java

@Transactional
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper,User>   implements UserService {

    @Resource
    private UserMapper userMapper;

    @Override
    public List<User> findAll(){
        return userMapper.findAll();
    }

    @Override
    public List<User> listUser(String username) {
        return userMapper.listUser(username);
    }

    @Override
    public List<User> listUser(String username, String password) {
        return userMapper.listUser(username,password);
    }
}

UserMapper.java

public interface UserMapper extends BaseMapper<User> {


    List<User> findAll();

    List<User> listUser(@Param("username")String username);

    List<User> listUser(@Param("username")String username,@Param("password")String password);

}

UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--名称空间：对应mapper层某个接口的包的全名称-->

<!--   namespace +  标签Id  ：

 key： com.example.demo.mapper.UserMapper.listUser   value: MappedStatement实例-->
<mapper namespace="com.example.demo.mapper.UserMapper">
    <select id="findAll" resultType="com.example.demo.entity.User">
        select * from user
    </select>
   <select id="listUser" resultType="com.example.demo.entity.User">
        select * from user where username = #{username} and password = #{password}
    </select>
</mapper>

_____________________________________________________________________________

重点来了

interceptor包下面的LoginInterceptor.java

public class LoginInterceptor implements HandlerInterceptor {

    @Autowired
    private HttpSession httpSession;

    //Controller逻辑执行之前
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("preHandle....");
        String uri = request.getRequestURI();
        System.out.println("当前路径："+uri);
        /**
         * HandlerMethod=>Controller中标注@RequestMapping的方法
         *  需要配置静态资源不拦截时，添加这块逻辑  => 前后端分离项目
         *
         */
        // 是我们的conrtoller中的方法
        if (!(handler instanceof HandlerMethod)) {
            return true;
        }
        if (httpSession.getAttribute("username") == null) {
            // 未登录跳转到登录界面
           throw  new RuntimeException("no login!");
        } else {
            return true;
        }
    }

    //Controller逻辑执行完毕但是视图解析器还未进行解析之前
    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle....");
    }

    //Controller逻辑和视图解析器执行完毕
    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("afterCompletion....");
    }
}

在config包下面建立 WebMvcConfig .java

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor())
                // 拦截规则 ，拦截那些路径
                .addPathPatterns("/**")
                // 那些路径不拦截
                .excludePathPatterns("/user/login","/error");
    }

    @Bean
    public LoginInterceptor loginInterceptor(){
        return new LoginInterceptor();
    }
}

这就是集成好的拦截器