public class LoginInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession(false);
        if (session != null && session.getAttribute("user") != null) {
            return true;
        }
        response.setStatus(401);
        return false;
    }
}

1.2 將自定義攔截器加入到系統(tǒng)配置

@Configuration
public class AppConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/**") // 攔截所有的接口
                .excludePathPatterns("/**/login.html"); // 排除的接口
    }
}

addPathPatterns : 表示要攔截的URL.

excludePathPatterns : 表示需要排除的URL

1.3 運行結(jié)果

1.4 總結(jié)

Spring 中的攔截器是通過動態(tài)代理和環(huán)繞通知的思想實現(xiàn)的.

2. 統(tǒng)一異常處理

統(tǒng)一異常處理使用的是 @ControllerAdvice + @ExceptionHandler 來實現(xiàn)的,

@ControllerAdvice 表示控制器通知類
@ExceptionHandler 是異常處理器

兩個結(jié)合表示當出現(xiàn)異常的時候執(zhí)行某個通知, 也就是執(zhí)行某個方法事件

2.1 代碼實現(xiàn)

@ControllerAdvice
@ResponseBody
public class ErrorAdvice {
    @ExceptionHandler(NullPointerException.class)
    public Object nullPointerException(NullPointerException e) {
        HashMap<String, Object> map = new HashMap<>();
        map.put("success",200);
        map.put("status",-1);
        map.put("message","空指針異常!");
        return map;
    }
}

2.2 運行結(jié)果

@RestController
@RequestMapping("/user")
public class UserController {
    @RequestMapping("/hi")
    public String say() {
        Object object = null;
        int i = object.hashCode();
        return "Hello";
    }
}

3. 統(tǒng)一數(shù)據(jù)返回格式

統(tǒng)一的數(shù)據(jù)返回格式可以使用 @ControllerAdvice + ResponseBodyAdvice 的方式實現(xiàn).

添加@ControllerAdvice
實現(xiàn)ResponseBodyAdvice接口, 并重寫beforeBodyWrite方法

3.1 代碼實現(xiàn)

@ControllerAdvice
public class ResponseAdvice implements ResponseBodyAdvice {
    /**
     * 內(nèi)容是否重寫, 返回true表示重寫
     */
    @Override
    public boolean supports(MethodParameter returnType, Class converterType) {
        return true;
    }
    @Override
    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
        // 統(tǒng)一數(shù)據(jù)格式的封裝
        HashMap<String, Object> result = new HashMap<>();
        result.put("success",200);
        result.put("status",1);
        result.put("data",body);
        return result;
    }
}

3.2 運行結(jié)果

@RestController
@RequestMapping("/user")
public class UserController {
    @RequestMapping("/index")
    public Object index() {
        User user = new User();
        user.setUsername("SpringAOP");
        user.setPassword("123456");
        return user;
    }
}