Spring进阶之@ControllerAdvice与统一异常处理

待我称王封你为后i 2022-02-27 01:05 223阅读 0赞

## @ControllerAdvice ##

Spring源码中有关`@ControllerAdvice`的注解如下：

> Specialization of \{@link Component @Component\} for classes that declare \{@link ExceptionHandler @ExceptionHandler\}, \{@link InitBinder @InitBinder\}, or \{@link ModelAttribute @ModelAttribute\} methods to be shared across multiple \{@code @Controller\} classes.

理解：

`@ControllerAdvice`是一个特殊的`@Component`，用于标识一个类，这个类中被以下三种注解标识的方法：`@ExceptionHandler`，`@InitBinder`，`@ModelAttribute`，将作用于所有的`@Controller`类的接口上。

那么，这个三个注解分别是什么意思，起到什么作用呢？

## @InitBinder ##

> Annotation that identifies methods which initialize the \{@link org.springframework.web.bind.WebDataBinder\} which will be used for populating command and form object arguments of annotated handler methods.  
> Such init-binder methods support all arguments that \{@link RequestMapping\} supports, except for command/form objects and corresponding validation result objects. Init-binder methods must not have a return value; they are usually declared as \{@code void\}.

作用：注册属性编辑器，对HTTP请求参数进行处理，再绑定到对应的接口，比如格式化的时间转换等。应用于单个@Controller类的方法上时，仅对该类里的接口有效。与@ControllerAdvice组合使用可全局生效。

示例：

@ControllerAdvice
    public class ActionAdvice { 
        
        @InitBinder
        public void handleException(WebDataBinder binder) { 
            binder.addCustomFormatter(new DateFormatter("yyyy-MM-dd HH:mm:ss"));
        }
    }

## @ExceptionHandler ##

作用：统一异常处理，也可以指定要处理的异常类型

示例：

@ControllerAdvice
    public class ActionAdvice { 
        
        @ExceptionHandler(Exception.class)
        @ResponseBody
        @ResponseStatus(HttpStatus.OK)
        public Map handleException(Exception ex) { 
            Map<String, Object> map = new HashMap<>();
            map.put("code", 400);
            map.put("msg", ex.toString());
            return map;
        }
    }

## @ModelAttribute ##

作用：绑定数据

示例：

@ControllerAdvice
    public class ActionAdvice { 
        
        @ModelAttribute
        public void handleException(Model model) { 
            model.addAttribute("user", "zfh");
        }
    }

在接口中获取前面绑定的参数：

@RestController
    public class BasicController { 
        
        @GetMapping(value = "index")
        public Map index(@ModelAttribute("user") String user) { 
            //...
        }
    }

--------------------

完整示例代码：

import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.format.datetime.DateFormatter;
    import org.springframework.http.HttpStatus;
    import org.springframework.ui.Model;
    import org.springframework.validation.Validator;
    import org.springframework.web.bind.WebDataBinder;
    import org.springframework.web.bind.annotation.*;
    
    import java.util.HashMap;
    import java.util.Map;
    
    /** * 统一异常处理 * @author zfh * @version 1.0 * @since 2019/1/4 15:23 */
    @ControllerAdvice
    public class ControllerExceptionHandler { 
    
        private Logger logger = LoggerFactory.getLogger(ControllerExceptionHandler.class);
    
        @InitBinder
        public void initMyBinder(WebDataBinder binder) { 
            // 添加对日期的统一处理
            //binder.addCustomFormatter(new DateFormatter("yyyy-MM-dd"));
            binder.addCustomFormatter(new DateFormatter("yyyy-MM-dd HH:mm:ss"));
    
            // 添加表单验证
            //binder.addValidators();
        }
    
        @ModelAttribute
        public void addMyAttribute(Model model) { 
            model.addAttribute("user", "zfh"); // 在@RequestMapping的接口中使用@ModelAttribute("name") Object name获取
        }
    
        @ExceptionHandler(value = Exception.class)
        @ResponseStatus(HttpStatus.OK)
        @ResponseBody // 如果使用了@RestControllerAdvice，这里就不需要@ResponseBody了
        public Map handler(Exception ex) { 
            logger.error("统一异常处理", ex);
            Map<String, Object> map = new HashMap<>();
            map.put("code", 400);
            map.put("msg", ex);
            return map;
        }
    }

测试接口：

@RestController
    public class TestAction { 
    
        @GetMapping(value = "testAdvice")
        public JsonResult testAdvice(@ModelAttribute("user") String user, Date date) throws Exception { 
            System.out.println("user: " + user);
            System.out.println("date: " + date);
            throw new Exception("直接抛出异常");
        }
    }

--------------------

## 高阶应用–格式化时间转Date ##

使用`@ControllerAdvice` \+ `@InitBinder`，可将http请求参数中的时间自动转换成Date类型。

@InitBinder
        public void initBinder(WebDataBinder binder) { 
            GenericConversionService genericConversionService = (GenericConversionService) binder.getConversionService();
            if (genericConversionService != null) { 
                genericConversionService.addConverter(new DateConverter());
            }
        }

自定义的时间类型转换器：

import org.springframework.core.convert.converter.Converter;
    import org.springframework.util.StringUtils;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    
    /** * 日期转换类 * 将标准日期、标准日期时间、时间戳转换成Date类型 */
    public class DateConverter implements Converter<String, Date> { 
        private static final String dateFormat = "yyyy-MM-dd HH:mm:ss";
        private static final String shortDateFormat = "yyyy-MM-dd";
        private static final String timeStampFormat = "^\\d+$";
    
        @Override
        public Date convert(String value) { 
    
            if(StringUtils.isEmpty(value)) { 
                return null;
            }
    
            value = value.trim();
    
            try { 
                if (value.contains("-")) { 
                    SimpleDateFormat formatter;
                    if (value.contains(":")) { 
                        formatter = new SimpleDateFormat(dateFormat);
                    } else { 
                        formatter = new SimpleDateFormat(shortDateFormat);
                    }
                    return formatter.parse(value);
                } else if (value.matches(timeStampFormat)) { 
                    Long lDate = new Long(value);
                    return new Date(lDate);
                }
            } catch (Exception e) { 
                throw new RuntimeException(String.format("parser %s to Date fail", value));
            }
            throw new RuntimeException(String.format("parser %s to Date fail", value));
        }
    }

扩展：

`@RestControllerAdvice` = `@ControllerAdvice` \+ `@ResponseBody`

--------------------

参考：

> 1.  [Spring Boot 系列（八）@ControllerAdvice 拦截异常并统一处理][Spring Boot _ControllerAdvice]
> 2.  [SpringMVC重要注解（二）@ControllerAdvice][SpringMVC_ControllerAdvice]
> 3.  [精通Spring Boot —— 第十五篇：使用@ControllerAdvice处理异常][Spring Boot _ _ControllerAdvice]
> 4.  [@InitBinder][InitBinder]
> 5.  [SpringMVC中利用@InitBinder来对页面数据进行解析绑定][SpringMVC_InitBinder]

[Spring Boot _ControllerAdvice]: https://www.cnblogs.com/magicalSam/p/7198420.html
[SpringMVC_ControllerAdvice]: https://blog.csdn.net/w372426096/article/details/78429141
[Spring Boot _ _ControllerAdvice]: https://yq.aliyun.com/articles/647428
[InitBinder]: https://blog.csdn.net/zero__007/article/details/80466392
[SpringMVC_InitBinder]: https://www.cnblogs.com/heyonggang/p/6186633.html