Best practise - exception handling in service/dao/business layers

问题

What is the best practise to do exception handling when error is thrown in different layers.

I have 4 layers of code - DAO , SERVICE , BUSINESS, PRESENTATION. I am trying to catch some run time exception in the dao layer and want it to display in the presentation layer with some message.Is the below approach a good one ?

Here in the code snippets - DataException is my runtime exception class.Service and Business exception classes are my checked exception implementation classes.

Code snippets below:

In dao layer , a method checks for some value from database

class dao{
public User getUser() throws DataException{

User user = null;

try
{
//some operation to fetch data using hibernatetemplate
}catch(Exception ex){
throw new DataException(ex.getMessage());
}

return user;
 }
 }

service.java

 class service{
 public User getUser(String username) throws ServiceException{

 User user = null;

 try
{
//some operation to fetch data using dao method
 dao.getuser(username);
 }catch(DataException ex){
throw new ServiceException(ex.getMessage());
}

 return user;
}
}

business.java

 class business{
 public User getUser(String username) throws BusinessException{

 User user = null;

 try
{
//some operation to fetch data using dao method
 service.getuser(username);
 }catch(ServiceException ex){
throw new BusinessException(ex.getMessage());
}

 return user;
}
}

In presentation layer , let it be a controller class

 class Presentation{
 public User getUser(String username) throws BusinessException{

  User user = null;


 //some operation to fetch data using business method
 business.getUser(username);

  return user;
 }
 }

Assume from the presentation layer message is thrown to the user in the front end JSP page ..

回答1:

You should encapsulate the business exception in a PresentationException with a code. This code is used to render the error message in a localized way. The code allows the error message to be purely in the presentation and have different messages for different views.

 try{
  getUser(...);
 }catch(BusinessException b){
   throw new PresentationException(ErrorEnum.GetUserError,b);
 }

This execption should be put in the model (view context) somehow.

In the JSP you can do something like:

if(exception){
 if(debug) print(exception.getCause().getMessage());
 else print(localize(exception.getErrorCode());
}

来源：https://stackoverflow.com/questions/9238180/best-practise-exception-handling-in-service-dao-business-layers

标签

java

exception

runtime