【Spring】Spring全局异常处理（二）

• Spring全局异常处理
• • @ControllerAdvice和@ExceptionHandler
  • • 定义
    • Order

Spring全局异常处理（一）.

从源码的介绍里可以大概的总结如下：

• 一个注解了ControllerAdvice的类。可以定义@ExceptionHandler、@InitBinder、@ModelAttribute的方法。这样的类可以处理@Controller抛出来的异常
• 可以通过注解@Order、@Priority或者实现Ordered接口定义优先级
• 对于@ExceptionHandler的方法，处理异常的顺序是：优先级更高的类>异常的父类的处理方法>异常本身的处理方法
• 默认地，@ControllerAdvice的方法适用于所有的controllers.可以通过annotations、basePackageClasses、basePackages、value、assignableTypes指定相应的controllers。如果多个同时指定，只要满足其中一个即可

使用@ControllerAdvice和@ExceptionHandler组合可以处理controller抛出来的异常。例子实践一下。

异常处理

@ControllerAdvice
public class ControllerAdviceExample {
    
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response, Exception ex) {
      Map resultMap = new HashMap<>();
      resultMap.put("message", "@ControllerAdvice & @ExceptionHandler handle exception!!!!!!!!!!!");
      return resultMap;
    }
}

控制器

@RestController
@RequestMapping("controllerAdvice")
public class ControllerAdviceController {
    @GetMapping
    public String handleException() throws Exception {
        throw new ClassNotFoundException("--------handleException----------");
    }
}

运行起来后访问/controllerAdvice得到如下结果：

证明我们定义的全局异常处理起作用了。

可以通过注解@link org.springframework.core.annotation.Order @Order、@link javax.annotation.Priority @Priority或者实现@link org.springframework.core.Ordered Ordered接口定义优先级

我们定义两个ControllerAdvice类，分别用@Order定义优先顺序。

@Order(1)

@ControllerAdvice
// 定义优先级
@Order(1)
public class ControllerAdviceOrder1 {
  
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response, Exception ex) {
        Map resultMap = new HashMap<>();
        resultMap.put("message", getClass().getName() + " handles exception!!!!!!!!!!!");
        return resultMap;
    }
}

@Order(2)

@ControllerAdvice
// 定义优先级
@Order(2)
public class ControllerAdviceOrder2 {
    
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response, Exception ex) {
      Map resultMap = new HashMap<>();
      resultMap.put("message", getClass().getName() + " handles exception!!!!!!!!!!!");
      return resultMap;
    }
}

重新启动程序后访问/controllerAdvice得到如下结果：

@Order的值越小优先级越高，@Priority的使用方法和@Order是一样的，接下来我们看看如何实现Ordered接口定义优先级

优先级为1的实现

@ControllerAdvice
public class ControllerAdviceOrdered1 implements Ordered{
  
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response, Exception ex) {
        Map resultMap = new HashMap<>();
        resultMap.put("message", getClass().getName() + " handles exception!!!!!!!!!!!");
        return resultMap;
    }

    // 实现该函数，返回优先级的数值
    @Override
    public int getOrder() {
        return 1;
    }
}

优先级为2的实现

@ControllerAdvice
public class ControllerAdviceOrdered2 implements Ordered {
    
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response,
            Exception ex) {
        Map resultMap = new HashMap<>();
        resultMap.put("message", getClass().getName() + " handles exception!!!!!!!!!!!");
        return resultMap;
    }
    
    // 实现该函数，返回优先级的数值
    @Override
    public int getOrder() {
        return 2;
    }
}

启动程序后访问/controllerAdvice得到如下结果：

接口Ordered通过实现getOrder函数实现优先级的赋值。

实现接口PriorityOrdered的类优先级低于实现了接口Ordered的类

Ordered定义优先级为1的ControllerAdvice

@ControllerAdvice
public class ControllerAdviceOrdered1 implements Ordered {
    
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response,
            Exception ex) {
        Map resultMap = new HashMap<>();
        resultMap.put("message", getClass().getName() + " handles exception!!!!!!!!!!!");
        return resultMap;
    }
    
    // 实现该函数，返回优先级的数值
    @Override
    public int getOrder() {
        return 1;
    }
}

ControllerAdvicePriorityOrdered定义优先级为2的ControllerAdvice

@ControllerAdvice
public class ControllerAdvicePriorityOrdered implements PriorityOrdered{
    @ExceptionHandler(value = { ClassNotFoundException.class })
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public Map controllerAdvice(HttpServletRequest request, HttpServletResponse response,
            Exception ex) {
        Map resultMap = new HashMap<>();
        resultMap.put("message", getClass().getName() + " handles exception!!!!!!!!!!!");
        return resultMap;
    }
    
    // 实现该函数，返回优先级的数值
    @Override
    public int getOrder() {
        return 1;
    }
}

启动程序后访问/controllerAdvice得到如下结果：

虽然都定义了优先级为1，但是会先调用Ordered的实现。

未完待续

蜗牛速度般的学习，慢牛般的成长^-

​更多文章欢迎关注“三横兰”