boot_自定义异常

0.自定义异常错误页

error/404.html error/5xx.html；有精确的错误状态码页面就匹配精确，没有就找 4xx.html；如果都没有就触发白页

1.第一种：@ControllerAdvice+@ExceptionHandler处理全局异常

@ControllerAdvice+@ExceptionHandler处理全局异常；底层是 ExceptionHandlerExceptionResolver 支持的

package com.atguigu.admin.exception;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

/**
 * 处理整个web controll的异常
 */
@ControllerAdvice
@Slf4j
public class GlobalExceptionHandler {
    @ExceptionHandler({ArithmeticException.class,NullPointerException.class}) //处理异常
    public String handleArithException(Exception e){
        log.error("异常是:{}",e);
        return "login"; //视图地址
    }
}

2.第二种：@ResponseStatus+自定义异常

• @ResponseStatus+自定义异常 ；底层是 ResponseStatusExceptionResolver ，把responsestatus注解的信息底层调用 response.sendError(statusCode, resolvedReason)；tomcat发送的/error
• Spring底层的异常，如 参数类型转换异常；DefaultHandlerExceptionResolver 处理框架底层的异常。response.sendError(HttpServletResponse.SC_BAD_REQUEST, ex.getMessage()); 

package com.atguigu.admin.exception;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

@ResponseStatus(value = HttpStatus.FORBIDDEN,reason = "用户数量太多")
public class UserTooManyException extends RuntimeException{
    public UserTooManyException() {
    }

    public UserTooManyException(String message) {
        super(message);
    }

}

3.第三种：自定义实现 HandlerExceptionResolver 处理异常

• 自定义实现 HandlerExceptionResolver 处理异常；可以作为默认的全局异常处理规则

• ErrorViewResolver 实现自定义处理异常；

• response.sendError 。error请求就会转给controller
• 你的异常没有任何人能处理。tomcat底层 response.sendError。error请求就会转给controller

• basicErrorController 要去的页面地址是 ErrorViewResolver ；

package com.atguigu.admin.exception;

import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@Component
@Order(value = Ordered.HIGHEST_PRECEDENCE) //优先级，数字越小优先级越高
public class CustomerHandlerExceptionResolver implements HandlerExceptionResolver {
    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        try {
            response.sendError(511, "我喜欢的错误");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return new ModelAndView();
    }
}

4xx.html:

<div class="container ">

        <section class="error-wrapper text-center">
            <h1><img alt="" src="images/404-error.png"></h1>
            <h2 th:text="${status}">page not found</h2>
            <h3 th:text="${message}">We Couldn’t Find This Page</h3>
            <a class="back-btn" th:href="@{/main.html}"> Back To Home</a>
        </section>

</div>