SSM integration exception handler and project exception handling scheme

Catalog

One 、 Exception handler

Two 、 Project exception handling scheme

Project exception classification

Project exception handling scheme

Project exception handling

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One 、 Exception handler

In the process of program development, it is inevitable to encounter abnormal phenomena

The common locations and causes of abnormal phenomena are as follows ：

■ Exceptions thrown inside the framework ： Caused by non-conforming use

■ Exceptions thrown by the data layer ： Due to external server failure （ for example ： Server access timeout ）

■ Exceptions thrown by the business layer ： Due to business logic writing errors （ for example ： Traverse business writing operations , Cause index exceptions, etc ）

■ Exceptions thrown by the presentation layer ： Due to data collection 、 Verification and other rules lead to （ for example ： Mismatched data types cause exceptions ）

■ Exception thrown by tool class ： Because the writing of tool books is not rigorous and robust enough, it leads to （ for example ： The connection that needs to be released has not been released for a long time, etc ）

1、 Exceptions occur at all levels , Which layer is the exception handling code written on ？

All exceptions are thrown to the presentation layer for processing

2、 The presentation layer handles exceptions , Each method is written separately , The amount of code written is huge and the meaning is not strong , How to solve ？

AOP thought

Exception handler

Centralized 、 Handle exceptions in the project in a unified way

@RestControllerAdvice
public class ProjectExceptionAdvice{
    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex){
        return new Result(666,null);
    }
}

name ：@RestControllerAdvice

type ： Class annotation

Location ：Rest Style development controller enhancement class definition

effect ： by Rest Enhance the controller class developed in style

Example ：

@RestControllerAdvice
public class ProjectExceptionAdvice{
}

explain ： This annotation comes with @ResponseBody Annotations and @Component annotation , Have corresponding functions

name ：@ExceptionHandler

type ： Method notes

Location ： Controller method dedicated to exception handling

effect ： Set the handling scheme of the specified exception , The function is equivalent to the controller method , Terminate the execution of the original controller after an exception occurs , And go to the current method to execute

Example ：

@RestControllerAdvice
public class ProjectExceptionAdvice{
    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex){
        return new Result(666,null);
    }
}

explain ： Such methods can vary according to the exceptions handled , Make multiple methods to deal with the corresponding exceptions respectively

Exception handler processing effect comparison ：

When there is no abnormality ：

  When there is abnormal ：

  Two 、 Project exception handling scheme

Project exception classification

Business exceptions （BusinessException）

Exceptions caused by standardized user behavior

Exceptions caused by irregular user behavior

System exception （SystemException）

Predictable and unavoidable exceptions during project operation

Other anomalies （Exception）

Unexpected exceptions by programmers

Project exception handling scheme

Business exceptions （BusinessException）

Send the corresponding message to the user , Remind the standard operation

System exception （SystemException）

Send a fixed message to the user , Appease users

Send specific messages to O & M personnel , Remind maintenance

Log

Other anomalies （Exception）

Send a fixed message to the user , Appease users

Send specific messages to programmers , Remind maintenance （ Within the expected range ）

Log

Project exception handling

1、 Custom item exception system level exception

// Custom exception handler , Used to encapsulate exception information , Classify exceptions 
public class SystemException extends RuntimeException{
    private Integer code;

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public SystemException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public SystemException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }
}

2、 Custom item business level exception

// Custom exception handler , Used to encapsulate exception information , Classify exceptions 
public class BusinessException extends RuntimeException{
    private Integer code;

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public BusinessException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public BusinessException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }
}

3、 Custom exception code （ Keep adding ）

public class Code {
    public static final Integer SYSTEM_UNKNOW_ERROR = 50001;
    public static final Integer SYSTEM_TIMEOUT_ERROR = 50002;

    public static final Integer PROJECT_VALIDATE_ERROR = 60001;
    public static final Integer PROJECT_BUSINESS_ERROR = 60002;
}

4、 Trigger custom exception

@Service
public class BookServiceImpl implements BookService {
    @Autowired
    private BookDao bookDao;

    public Book getById(Integer id) {
        // Simulate business exceptions , Wrap as a custom exception 
        if(id < 0){
            throw new BusinessException(Code.PROJECT_BUSINESS_ERROR," Do not operate illegally !");
        }
        return bookDao.getById(id);
    }
}

5、 Intercept and handle exceptions

//@RestControllerAdvice Used to identify that the current class is REST Exception handler corresponding to style 
@RestControllerAdvice
public class ProjectExceptionAdvice {
    //@ExceptionHandler Used to set the exception type corresponding to the current processor class 
    @ExceptionHandler(SystemException.class)
    public Result doSystemException(SystemException ex){
        // Log 
        // Send a message to O & M 
        // Send mail to developers ,ex Object to the developer 
        return new Result(ex.getCode(),null,ex.getMessage());
    }

    @ExceptionHandler(BusinessException.class)
    public Result doBusinessException(BusinessException ex){
        return new Result(ex.getCode(),null,ex.getMessage());
    }

    // In addition to custom exception handlers , Keep right Exception Exception handling of type , Used to handle unexpected exceptions 
    @ExceptionHandler(Exception.class)
    public Result doOtherException(Exception ex){
        // Log 
        // Send a message to O & M 
        // Send mail to developers ,ex Object to the developer 
        return new Result(Code.SYSTEM_UNKNOW_ERROR,null," The system is busy , Please contact the Administrator ！");
    }
}

6、 Exception handler effect comparison