initial work on the exception handler example

spring-security-rest-full/src/main/java/org/baeldung/web/error/RestResponseEntityExceptionHandler.java

@@ -0,0 +1,78 @@
+package org.baeldung.web.error;
+
+import javax.persistence.EntityNotFoundException;
+
+import org.hibernate.exception.ConstraintViolationException;
+import org.springframework.dao.DataAccessException;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.dao.InvalidDataAccessApiUsageException;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.converter.HttpMessageNotReadableException;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.context.request.WebRequest;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
+
+@ControllerAdvice
+public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
+
+    public RestResponseEntityExceptionHandler() {
+        super();
+    }
+
+    // API
+
+    // 400
+
+    @ExceptionHandler({ ConstraintViolationException.class, DataIntegrityViolationException.class })
+    public ResponseEntity<Object> handleBadRequest(final RuntimeException ex, final WebRequest request) {
+        final String bodyOfResponse = "This should be application specific";
+        return handleExceptionInternal(ex, bodyOfResponse, new HttpHeaders(), HttpStatus.BAD_REQUEST, request);
+    }
+
+    @Override
+    protected ResponseEntity<Object> handleHttpMessageNotReadable(final HttpMessageNotReadableException ex, final HttpHeaders headers, final HttpStatus status, final WebRequest request) {
+        final String bodyOfResponse = "This should be application specific";
+        // ex.getCause() instanceof JsonMappingException, JsonParseException // for additional information later on
+        return handleExceptionInternal(ex, bodyOfResponse, headers, HttpStatus.BAD_REQUEST, request);
+    }
+
+    @Override
+    protected ResponseEntity<Object> handleMethodArgumentNotValid(final MethodArgumentNotValidException ex, final HttpHeaders headers, final HttpStatus status, final WebRequest request) {
+        final String bodyOfResponse = "This should be application specific";
+        return handleExceptionInternal(ex, bodyOfResponse, headers, HttpStatus.BAD_REQUEST, request);
+    }
+
+    // 403
+
+    // 404
+
+    @ExceptionHandler(value = { EntityNotFoundException.class })
+    protected ResponseEntity<Object> handleBadRequest(final EntityNotFoundException ex, final WebRequest request) {
+        final String bodyOfResponse = "This should be application specific";
+        return handleExceptionInternal(ex, bodyOfResponse, new HttpHeaders(), HttpStatus.NOT_FOUND, request);
+    }
+
+    // 409
+
+    @ExceptionHandler({ InvalidDataAccessApiUsageException.class, DataAccessException.class })
+    protected ResponseEntity<Object> handleConflict(final RuntimeException ex, final WebRequest request) {
+        final String bodyOfResponse = "This should be application specific";
+        return handleExceptionInternal(ex, bodyOfResponse, new HttpHeaders(), HttpStatus.CONFLICT, request);
+    }
+
+    // 412
+
+    // 500
+
+    @ExceptionHandler({ NullPointerException.class, IllegalArgumentException.class, IllegalStateException.class })
+    /*500*/public ResponseEntity<Object> handleInternal(final RuntimeException ex, final WebRequest request) {
+        logger.error("500 Status Code", ex);
+        final String bodyOfResponse = "This should be application specific";
+        return handleExceptionInternal(ex, bodyOfResponse, new HttpHeaders(), HttpStatus.INTERNAL_SERVER_ERROR, request);
+    }
+
+}