SpringBoot Learning Global Exception Handling Settings (Return to JSON)

SpringBoot Learning - Global Exception Handling Settings (Return to JSON)

need

1. Now we are used to using ajax to initiate requests, so we often need to return a json or string on the server.
2. Control global exception handling.
3. If you use try in a single method, catch wraps the method, which is a lot of work and will be thrown abnormally, resulting in the method transactions of @Transactional annotation not rolled back.

illustrate

1. Use @ControllerAdvice annotation
2. Use @ExceptionHandler annotation

@ControllerAdvice

This annotation is a new annotation added after spring 2.3. It is mainly used to provide assistance to some low-invasive enhancements of the common needs of Controller, and is used on the @RequestMapping annotation method.

@ExceptionHandler

This annotation is an annotation used with @ExceptionHandler. It is a custom error handler. You can assemble the json string by yourself and return to the page.

Code

Create a global exception handling class as follows:

If different exceptions have different operations to implement, you only need to change the value of @ExceptionHandler's value to be different. Multiple different exceptions can be handled at the same time, but the inclusion state cannot occur.

 import javax.servlet.http.HttpServletRequest;import org.springframework.web.bind.annotation.ControllerAdvice;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.ResponseBody;@ControllerAdvice@ResponseBodypublic class GlobalExceptionHandler { /** * All exceptions reported errors* @param request * @param exception * @return * @throws Exception */ @ExceptionHandler(value=Exception.class) public String allExceptionHandler(HttpServletRequest request, Exception exception) throws Exception { exception.printStackTrace(); System.out.println("I reported an error: "+exception.getLocalizedMessage()); System.out.println("I reported an error: "+exception.getCause()); System.out.println("I reported an error: "+exception.getSuppressed()); System.out.println("I reported an error: "+exception.getMessage()); System.out.println("I reported an error: "+exception.getStackTrace()); return "Server exception, please contact the administrator!"; } }

Simulate an exception throwing class. The following example is to throw a null pointer exception and the denominator is not an exception

 import org.springframework.steretype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;@Controller@RequestMapping("/exceptionTest")@ResponseBodypublic class ExceptionTest { @RequestMapping("/test") public String test(){ Message msg = null; msg.toString(); createException(); return "I am normal"; } private void createException(){ int i = 5/0; }}

Start Springboot, execution results

Because the returned string, you can also use the json tool class to encapsulate it and return a json string

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