Springboot Unified Exception Handling

For a database-related Spring MVC project, we typically configure the transaction at the service layer, and the service layer throws a run-time exception when the database operation fails, and the spring things manager rolls back.

As a result, our Controller layer will have to try-catch the Service layer exception, otherwise it will return some unfriendly error message to the client.

However, each method body of the Controller layer writes some templated Try-catch code, which is difficult to see and maintenance, especially when different exceptions to the Service layer are handled differently.

/** * Manual handling of Service layer exceptions and data check exceptions * @param dog * @param errors * @return*/@PostMapping (Value="") appresponse Add (@Validated (Add.class) @RequestBody dog Dog, Errors Errors) {Appresponse resp=NewAppresponse (); Try {        //Data Validationbsutil.controllervalidate (Errors); //Perform businessDog Newdog =Dogservice.save (dog); //Return DataResp.setdata (Newdog); }Catch(businessexception e) {logger.error (E.getmessage (), E);    Resp.setfail (E.getmessage ()); }Catch(Exception e) {logger.error (E.getmessage (), E); Resp.setfail ("operation failed! "); }    returnresp;}

This article explains the use of @ControllerAdvice + @ExceptionHandler for the global controller layer exception handling, as long as the design is correct, you can no longer do try-catch in the controller layer!

Moreover, the @Validated validator annotations of the exception, can also be processed together, no need to manually determine the binding check results Bindingresult/errors!

[Email protected] Annotations Define global exception handling classes

// Uniform handles exceptions in this class, global interception of specified exceptions @ControllerAdvice  Public class Exceptionhandle {

[email protected] Annotation declaration exception handling method

//Uniform handles exceptions in this class, global interception of specified exceptions@ControllerAdvice Public classExceptionhandle {Private StaticFinal Logger Logger = Loggerfactory.getlogger (exceptionhandle.class); @ExceptionHandler (Value= Exception.class)//assert that the exception class was captured@ResponseBody//returned to the browser is a JSON format, there is no @restcontroller, so this statement @responsebody     PublicResult handle (Exception e) {return ' ERROR! ";    }}

Method HandleException () handles the exception of the Exception and its subclasses thrown by all Controller layers.

Examples of implementing unified exception Management:

1. Encapsulate the returned result information and create a new result class

 Public classResult<t> {    /** * ERROR code*/    PrivateInteger Code; /** * Prompt information*/    PrivateString msg; /** * Specific content*/    PrivateT data;  PublicResult () {} PublicResult (Integer code, String msg) { This(Code, MSG,NULL); }     PublicResult (Integer code, String msg, T data) { This. Code =Code;  This. msg =msg;  This. data =data; } //。。。 }

2. To facilitate the processing of results information, the new result Information tool class: Resultutils

 Public classResultutil { Public StaticResult Success (ObjectObject) {        return NewResult (0,"Success",Object); }     Public StaticResult Success () {returnSuccessNULL); }     Public StaticResult Error (Integer code, String msg) {return NewResult (code, MSG); }}

3. To facilitate the processing of exception information, the custom exception information class: Girlexception

 Public classGirlexception extends RuntimeException {//This place does not write exception, because spring is a transaction rollback only for runtime exceptions,//If the exception is thrown, the transaction is not rolled back.     PrivateInteger Code;  Publicgirlexception (Resultenum resultenum) { This(Resultenum.getmsg (), Resultenum.getcode ()); }     Publicgirlexception (String message, Integer code) {super (message);  This. Code =Code; }     PublicInteger GetCode () {returnCode; }     Public voidSetcode (Integer code) { This. Code =Code; }}

4. To facilitate the unified management of the relationship between the exception code and information, create an enumeration class

 Public enumresultenum {unkown_error (-1,"Unknown error"), SUCCESS (0,"Success"), Primary_school (Ten,"you may still be in elementary school."), Middle_school ( -,"you may still be in junior high."),    ; PrivateInteger Code; PrivateString msg; Privateresultenum (Integer code,string msg) { This. msg =msg;  This. Code =Code; }     PublicString getmsg () {returnmsg; }     PublicInteger GetCode () {returnCode; }        }

5. Throwing exceptions at the service layer

 Public voidgetage (Integer id) throws Exception {Girl Girl=Girlrepository.getone (ID); Integer Age=Girl.getage (); if(Age <Ten) {            Throw Newgirlexception (Resultenum.primary_school); } Else if(Age >Ten&& Age < -) {            Throw Newgirlexception (Resultenum.middle_school); }    }

6. Continue throwing exceptions at the controller layer

// Unified exception handling, in the controller layer of the exception to Exceptionhandler to deal with    " Girls/getage/{id} " )    publicvoid getage (@PathVariable ("ID") Integer ID) throws Exception {        girlservice.getage (ID);    }

7. Handling Exceptions in Exceptionhandler

//Uniform handles exceptions in this class, global interception of specified exceptions@ControllerAdvice Public classExceptionhandle {Private StaticFinal Logger Logger = Loggerfactory.getlogger (exceptionhandle.class); @ExceptionHandler (Value= Exception.class)//assert that the exception class was captured@ResponseBody//returned to the browser is a JSON format, there is no @restcontroller, so this statement @responsebody     PublicResult handle (Exception e) {if(e instanceof girlexception) {girlexception girlexception=(girlexception) e; returnResultutil.error (Girlexception.getcode (), Girlexception.getmessage ()); } logger.error (""System Exception"", E); returnResultutil.error (ResultEnum.UNKOWN_ERROR.getCode (), RESULTENUM.UNKOWN_ERROR.GETMSG ()); }}

Springboot Uniform exception handling