@ExceptionHandler注解使用

青旅半醒 2023-07-03 14:30 23阅读 0赞

**@ExceptionHandler必须要求该方法必须要和出现问题的控制器在一个类中，才能生效。**

**如果别的类报空指针异常，则不会进该异常处理方法。**

**必须要结合@ControllerAdvice和@ExceptionHandler一起使用。**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTgxMTU0_size_16_color_FFFFFF_t_70][]

**注解后面是当出现空指针异常时，进入该控制器。setViewName是跳转到名字为error1的视图中**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTgxMTU0_size_16_color_FFFFFF_t_70 1][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNTgxMTU0_size_16_color_FFFFFF_t_70 2][]

**代码展示：**

package com.bjsxt.springbooterr.controller;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.ExceptionHandler;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.servlet.ModelAndView;
    
    @Controller
    public class UserController {
    
        @RequestMapping("/pagejump")
        public String pageJump(){
            String str=null;
            str.length();
            return "ok";
        }
    
        //该注解的作用是根据不同的异常跳转到不同的试图
        @ExceptionHandler(value = {java.lang.NullPointerException.class})
        public ModelAndView nullpointException(Exception e){
            ModelAndView mv=new ModelAndView();
            //将异常信息添加到ModelAndView中
            mv.addObject("error1",e.toString());
            //出现异常跳转到名为error1的视图
            mv.setViewName("error1");
            return mv;
        }
    }

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