24: Chapter 3: develop pass service: 7: user defined exceptions (to represent errors in the program); Create graceexceptionhandler to handle exceptions globally and uniformly (build JSON data of corre

explain ：

（1） stay 【Spring Boot E-commerce projects 16： User module 5 ： Registered interface development ： Custom exception classes ;（ To deal with 【 Not Controller Error in layer 】 To prepare for ;）】,

【Spring Boot E-commerce projects 17： User module 6 ： Registered interface development ： Use 【GlobalExceptionHandler】 To handle exceptions globally ;】 User defined exceptions have been introduced , And the strategy of handling custom exceptions globally ; Before reading this blog , Be sure to refer to the above two blogs first ;

          ●  What this blog does , The same as before ;; It's just , On the concrete realization , The mistake lies in the difference of yididididiu ;

stay 【23： The third chapter ： Developing a pass service ：6： Restrict users 60 Cannot repeat access within 【 Send a text message , Interface 】;】 in , In the interceptor , If it does “ The user is in 60 Repeat access within seconds 【 Send a text message , Interface 】” Of “ Wrong situation ” when , We just printed a sentence ;;; A formal practice , We can throw an exception , To represent this “ Wrong situation ”,

Catalog

One ： Formal development ;

1. stay 【imooc-news-dev-common】 In general engineering , establish exception package ;

2. Create custom exception ：MyCustomException;（ Inheritance is RuntimeException）

3. Create a tool class ：GraceException： According to what was passed in 【ResponseStatusEnum Enumeration class 】, establish （ And throw ） Corresponding customization MyCustomException Exception object ;

4. establish “ Handle exceptions uniformly handler class ”：GraceExceptionHandler class ： To handle exceptions globally , According to 【 Abnormal information 】 Convert to corresponding 【API Unified return object 】;

Two ： then ,  stay 【23： The third chapter ： Developing a pass service ：6： Restrict users 60 Cannot repeat access within 【 Send a text message , Interface 】;】 in , In the interceptor , If it does “ The user is in 60 Repeat access within seconds 【 Send a text message , Interface 】” Of “ Wrong situation ” when , You can throw a corresponding exception ;

3、 ... and ： effect ;

---

One ： Formal development ;

1. stay 【imooc-news-dev-common】 In general engineering , establish exception package ;

About exception related classes , We can put it in this bag ;

2. Create custom exception ：MyCustomException;（ Inheritance is RuntimeException）

package com.imooc.exception;

import com.imooc.grace.result.ResponseStatusEnum;

/**
 *  Custom exception ;
 *  Purpose ： Handle exception information uniformly ; Easy to manage , Easy to decouple ;
 */
public class MyCustomException extends RuntimeException {

    // Enumerating class objects 
    private ResponseStatusEnum responseStatusEnum;

    /**
     *  No arguments structure ; It's not what it takes. ;
     *  It's just , Because we declare a parameterized construct , Its nonparametric construction automatically GG 了 ;
     *  In order to prevent , There may be unnecessary trouble in the future , So I added a nonparametric structure to it ;
     */
    public MyCustomException() {
    }

    /**
     *  There are parametric structures ： according to 【 incoming , Representing an error message ResponseStatusEnum Enumerating class objects 】, Sure 
     *  Instantiate a 【MyCustomException Exception object 】
     * @param responseStatusEnum
     */
    public MyCustomException(ResponseStatusEnum responseStatusEnum) {
        super(" The exception status code is ：" + responseStatusEnum.status() +
                "; The specific information of the exception is ：" + responseStatusEnum.msg());
        this.responseStatusEnum = responseStatusEnum;
    }


    public ResponseStatusEnum getResponseStatusEnum() {
        return responseStatusEnum;
    }

    public void setResponseStatusEnum(ResponseStatusEnum responseStatusEnum) {
        this.responseStatusEnum = responseStatusEnum;
    }
}

explain ：

（1） Our custom exception , Inheritance is RuntimeException;; and , We are  【Spring Boot E-commerce projects 16： User module 5 ： Registered interface development ： Custom exception classes ;】 Custom exception in , Inheritance is Exception;

          ●  adopt 【Java Exception one ： Exception definition ; Classification of exceptions 】 You know ,RuntimeException Yes no check abnormal ;;; therefore , When we throw a in the program RuntimeException Abnormal times , We don't need to do it try-catch;;;; thus , We don't know much about code “ Invasive ”;

（2） It is known that , We are in the enumeration class , A lot of error messages are defined ;;;;; When something goes wrong with the program , Sometimes we can use the corresponding error messages , Build a custom MyCustomException Exception object ;

3. Create a tool class ：GraceException： According to what was passed in 【ResponseStatusEnum Enumeration class 】, establish （ And throw ） Corresponding customization MyCustomException Exception object ;

package com.imooc.exception;

import com.imooc.grace.result.ResponseStatusEnum;

/**
 *  Tool class ： according to 【 incoming , Representing an error message ResponseStatusEnum Enumerating class objects 】, system 
 *  A package 【 Our custom exception MyCustomException abnormal , The object of 】
 */
public class GraceException {

    /**
     *  According to what was passed in 【ResponseStatusEnum Enumeration class ,
     *  Create and throw our custom exception MyCustomException object 】
     * @param responseStatusEnum
     */
    public static void display(ResponseStatusEnum responseStatusEnum) {
        throw new MyCustomException(responseStatusEnum);
    }

}

explain ：

（1） Class content description ;

above , When we throw a custom exception in the program , This custom exception is thrown , Need to be captured by the container ;;; After the container catches this custom exception , We can put the corresponding specific error information , Throw to the front ;

therefore , At this point, we need to do a unified interception ; This is what follows ;

4. establish “ Handle exceptions uniformly handler class ”：GraceExceptionHandler class ： To handle exceptions globally , According to 【 Abnormal information 】 Convert to corresponding 【API Unified return object 】;

package com.imooc.exception;

import com.imooc.grace.result.GraceJSONResult;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 *  Unified exception interception and handling ;
 *  Specific information about exceptions can be provided , Build the corresponding GraceJSONResultAPI Unified return object , To the front end ;
 */
@ControllerAdvice
public class GraceExceptionHandler {

    @ExceptionHandler(MyCustomException.class)
    @ResponseBody
    public GraceJSONResult returnMyException(MyCustomException e) {
        e.printStackTrace();
        return GraceJSONResult.exception(e.getResponseStatusEnum());
    }
}

explain ：

（1） We are 【Spring Boot E-commerce projects 17： User module 6 ： Registered interface development ： Use 【GlobalExceptionHandler】 To handle exceptions globally ;】 in , Have done similar work ;;;; The content here , In this blog , There are introductions ;

（2） Take a look 【@ControllerAdvice】 annotation , In fact, you can understand , Here too AOP Principle , To achieve the ;

（3） here , It's based on 【 Abnormal information 】 Convert to corresponding 【API Unified return object 】;;; We are 【14： Chapter two ： Architecture back end project ：10： encapsulation “ Return results ”;】 in , Created 【API Unified return object 】 namely GraceJSONResult class ;

（4） Self perception （ Understanding may be biased or even wrong ）：

          ● Statement 1： The response is coming soon , That is, when you want to return to the front-end content （PS： This joint is the eye , Is not necessarily Controller Oh , It could also be an interceptor ;; namely , That returns information directly to the front end , Is not necessarily Controller, It may also be interceptors, etc ）, It is found that there is another MyCustomException abnormal ;;;;; that , We created here GraceExceptionHandler class , It USES 【 @ExceptionHandler(MyCustomException.class)】 The method of annotation , Will capture , According to 【 Abnormal information 】 Convert to corresponding 【API Unified return object 】 Of JSON Formatted data , Back to the front end ;

          ● Statement 2： This GraceExceptionHandler class , Real time monitoring 【 The point immediately to return to the front-end content 】（ here ,Controller And interceptors , It can be regarded as equivalent ）;; If , Its have MyCustomException abnormal ;;; that , We created here GraceExceptionHandler class , It USES 【 @ExceptionHandler(MyCustomException.class)】 The method of annotation , Will capture , According to 【 Abnormal information 】 Convert to corresponding 【API Unified return object 】 Of JSON Formatted data , Back to the front end ;

---

Two ： then ,  stay 【23： The third chapter ： Developing a pass service ：6： Restrict users 60 Cannot repeat access within 【 Send a text message , Interface 】;】 in , In the interceptor , If it does “ The user is in 60 Repeat access within seconds 【 Send a text message , Interface 】” Of “ Wrong situation ” when , You can throw a corresponding exception ;

---

3、 ... and ： effect ;

（1） First, the whole situation install Look at the whole project ;

（2） then , start-up 【user】 The main startup class of ;

（3） then , On the front page , Two consecutive visits 【 Send SMS interface 】;（PS： Remember to turn on SwitchHosts Virtual domain name ）