2.spring系列之404异常的捕获

回顾

我在之前发布了一篇spring统一返回的文章，最后提到是无法捕获404异常的，这里我们先来测试一下

@RestController
public class TestController {

    @GetMapping("/test")
    public String insert22() {
        return "hello";
    }
}

浏览器请求试一下 http://localhost:8080/xxx 报错

# Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Wed Dec 29 10:14:36 CST 2021

There was an unexpected error (type=Not Found, status=404).

springboot的处理方式

springboot处理这个404的异常是在 BasicErrorController中处理的

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {

	...........

	@Override
	public String getErrorPath() {
		return null;
	}

	@RequestMapping(produces = MediaType.TEXT_HTML_VALUE)
	public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
		HttpStatus status = getStatus(request);
		Map<String, Object> model = Collections
				.unmodifiableMap(getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.TEXT_HTML)));
		response.setStatus(status.value());
		ModelAndView modelAndView = resolveErrorView(request, response, status, model);
		return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
	}
	
	// 包含请求头 "Accept": "application/json" 会往这里走
	@RequestMapping
	public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
		HttpStatus status = getStatus(request);
		if (status == HttpStatus.NO_CONTENT) {
			return new ResponseEntity<>(status);
		}
		Map<String, Object> body = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
		return new ResponseEntity<>(body, status);
	}
	
	.............
}

只要请求路径/error就可以进去到errorHtml这个方法，在浏览器请求http://localhost:8080/error就可以进入这个方法

解决方案

我这使用的springboot的版本为2.3.7.RELEASE

方案1：重写/error的请求

这种方案会直接舍弃掉HTML响应方式，但是前后端分离模式下，后端已经很少使用ModelAndView了

@Controller
public class NoFoundController extends AbstractErrorController {

    public NoFoundController(ErrorAttributes errorAttributes) {
        super(errorAttributes);
    }

    /**
     * 默认路径/error，可以通过server.error.path配置
     */
    @RequestMapping(("${server.error.path:/error}"))
    public ResponseEntity<Map<String, Object>> notFoundError(HttpServletRequest request, HttpServletResponse response) {
        Map<String, Object> map = new HashMap<>(3);
        HttpStatus status = getStatus(request);
        map.put("code", status.value());
        map.put("data", null);
        map.put("message", status.toString());
        return new ResponseEntity<>(map, status);

    }

    /**
     * 在springboot2.3.0新增了server.error.path进行配置,这个废弃使用了，之前版本可以直接通过设置这个返回值修改默认/error的路径
     */
    @Override
    public String getErrorPath() {
        return null;
    }
}

方案2：重写BasicErrorController中的错误处理

这种方式无法将HTML响应的也改成了json返回，请求中要有"Accept": "application/json"才能走json响应

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class MyBasicErrorController extends BasicErrorController {

    public MyBasicErrorController(ServerProperties serverProperties) {
        // import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
        super(new DefaultErrorAttributes(), serverProperties.getError());
    }

    /**
     * JSON响应
     */
    @Override
    public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
        Map<String, Object> map = new HashMap<>();
        HttpStatus status = getStatus(request);
        map.put("code", status.value());
        map.put("data", null);
        map.put("message", status.toString());
        return new ResponseEntity<>(map, status);
    }

    /**
     * HTML响应,根据需求处理自己处理
     */
    @Override
    public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
       return super.errorHtml(request, response);
    }
}

其中MyBasicErrorController的构造函数可以参考spring自动装配ErrorMvcAutoConfiguration中的传值

//源码：
public class ErrorMvcAutoConfiguration {

	private final ServerProperties serverProperties;

	public ErrorMvcAutoConfiguration(ServerProperties serverProperties) {
		this.serverProperties = serverProperties;
	}

	@Bean
	@ConditionalOnMissingBean(value = ErrorAttributes.class, search = SearchStrategy.CURRENT)
	public DefaultErrorAttributes errorAttributes() {
        // ErrorAttributes 
		return new DefaultErrorAttributes();
	}

	@Bean
	@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
	public BasicErrorController basicErrorController(ErrorAttributes errorAttributes,
			ObjectProvider<ErrorViewResolver> errorViewResolvers) {
        // serverProperties.getError
		return new BasicErrorController(errorAttributes, this.serverProperties.getError(),
				errorViewResolvers.orderedStream().collect(Collectors.toList()));
	}
    ........
}

最后附上完整代码：

@Getter
public class BusinessException extends RuntimeException {
    private Integer code;

    public BusinessException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public BusinessException(String message) {
        super(message);
    }
}
--------------------------------------------------------------------------------------------

@ControllerAdvice
@ResponseBody
@Slf4j
public class GlobalException {

    @ExceptionHandler(value = BusinessException.class)
    public ResponseModel<Void> businessExceptionError(BusinessException e) {
        log.error("业务异常", e);
        if (e.getCode() != null) {
            return ResponseModel.error(e.getCode(), e.getMessage());
        }
        return ResponseModel.error(e.getMessage());
    }

    @ExceptionHandler(value = Exception.class)
    public ResponseModel<Void> exceptionError(Exception e) {
        log.error("系统异常", e);
        return ResponseModel.error();
    }
}
--------------------------------------------------------------------------------------------
@Getter
public enum ResponseEnum {
    SUCCESS(0, "OK"),
    PARAMETER_ERROR(1,"参数异常"),

    NO_FOUND(404,"not found"),
    SYSTEM_ERROR(500, "服务器异常，请联系管理员");

    ResponseEnum(Integer code, String message) {
        this.code = code;
        this.message = message;
    }

    private final Integer code;
    private final String message;
}
--------------------------------------------------------------------------------------------

public class ResponseModel<T> {
    private Integer code;
    private String message;
    private T data;

    public ResponseModel(Integer code, String message, T data) {
        this.code = code;
        this.message = message;
        this.data = data;
    }

    public static ResponseModel<Void> ok() {
        return ok(null);
    }

    public static <T> ResponseModel<T> ok(T data) {
        return new ResponseModel<>(ResponseEnum.SYSTEM_ERROR.getCode(), ResponseEnum.SYSTEM_ERROR.getMessage(), data);
    }

    public static <T> ResponseModel<T> ok(T data, String message) {
        return new ResponseModel<>(ResponseEnum.SYSTEM_ERROR.getCode(), message, data);
    }

    public static ResponseModel<Void> error(Integer statusCode, String message) {
        return new ResponseModel<>(statusCode, message, null);
    }

    public static ResponseModel<Void> error(String message) {
        return error(ResponseEnum.SYSTEM_ERROR.getCode(), message);
    }

    public static ResponseModel<Void> error() {
        return error(ResponseEnum.SYSTEM_ERROR.getCode(), ResponseEnum.SYSTEM_ERROR.getMessage());
    }
}
--------------------------------------------------------------------------------------------
@Controller
public class NoFoundController extends AbstractErrorController {

    public NoFoundController(ErrorAttributes errorAttributes) {
        super(errorAttributes);
    }

    /**
     * 默认路径/error，可以通过server.error.path配置
     */
    @RequestMapping(("${server.error.path:/error}"))
    public ResponseEntity<Map<String, Object>> notFoundError(HttpServletRequest request, HttpServletResponse response) {
        Map<String, Object> map = new HashMap<>(3);
        HttpStatus status = getStatus(request);
        map.put("code", status.value());
        map.put("data", null);
        map.put("message", status.toString());
        return new ResponseEntity<>(map, status);

    }

    /**
     * 在springboot2.3.0新增了server.error.path进行配置,这个废弃使用了，之前版本可以直接通过设置这个返回值修改默认/error的路径
     */
    @Override
    public String getErrorPath() {
        return null;
    }
}

感谢各位小伙伴阅读到最后，如有错误，敬请指正。