Rest Exception Handling & Rest Global Exception Handling

 Rest Exception Handling & Rest Global Exception Handling:

Rest Exception Handling:

StudentErrorResponse.java

package com.luv2code.demo.rest;

public class StudentErrorResponse {

    private int status;
    private String message;
    private long timeStamp;

    public StudentErrorResponse() {

    }

    public StudentErrorResponse(int status, String message, long timeStamp) {
        this.status = status;
        this.message = message;
        this.timeStamp = timeStamp;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public long getTimeStamp() {
        return timeStamp;
    }

    public void setTimeStamp(long timeStamp) {
        this.timeStamp = timeStamp;
    }
}

StudentNotFoundException.java

package com.luv2code.demo.rest;

public class StudentNotFoundException extends RuntimeException {

    public StudentNotFoundException(String message) {
        super(message);
    }

    public StudentNotFoundException(String message, Throwable cause) {
        super(message, cause);
    }

    public StudentNotFoundException(Throwable cause) {
        super(cause);
    }
}

StudentRestController.java

package com.luv2code.demo.rest;

import com.luv2code.demo.entity.Student;
import jakarta.annotation.PostConstruct;
import org.springframework.http.HttpStatus;
import org.springframework.http.HttpStatusCode;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;

@RestController
@RequestMapping("/api")
public class StudentRestController {

    private List<Student> theStudents;

    // define @PostConstruct to load the student data ... only once!

    @PostConstruct
    public void loadData() {

        theStudents = new ArrayList<>();

        theStudents.add(new Student("Poornima", "Patel"));
        theStudents.add(new Student("Mario", "Rossi"));
        theStudents.add(new Student("Mary", "Smith"));
    }


    // define endpoint for "/students" - return a list of students

    @GetMapping("/students")
    public List<Student> getStudents() {

        return theStudents;
    }

    // define endpoint or "/students/{studentId}" - return student at index

    @GetMapping("/students/{studentId}")
    public Student getStudent(@PathVariable int studentId) {

        // just index into the list ... keep it simple for now

        // check the studentId again list size

        if ( (studentId >= theStudents.size()) || (studentId < 0)) {
            throw new StudentNotFoundException("Student id not found - " + studentId);
        }

        return theStudents.get(studentId);
    }
    //
    // Add an exception handler using @ExceptionHandler
    //


    // Controller-Level Scope
    // The annotated method will only handle exceptions thrown by the controller methods in the same class.

    @ExceptionHandler
    public ResponseEntity<StudentErrorResponse> handleException(StudentNotFoundException exc) {

        // create a StudentErrorResponse

        StudentErrorResponse error = new StudentErrorResponse();

        error.setStatus(HttpStatus.NOT_FOUND.value()); //404
        error.setMessage(exc.getMessage());
        error.setTimeStamp(System.currentTimeMillis());

        // return ResponseEntity

        return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
    }

    // add another exception handler ... to catch any exception (catch all)

    @ExceptionHandler
    public ResponseEntity<StudentErrorResponse> handleException(Exception exc) {

        // create a StudentErrorResponse
        StudentErrorResponse error = new StudentErrorResponse();

        error.setStatus(HttpStatus.BAD_REQUEST.value()); //400
        error.setMessage(exc.getMessage());
        error.setTimeStamp(System.currentTimeMillis());

        // return ResponseEntity
        return new ResponseEntity<>(error, HttpStatus.BAD_REQUEST);
    }
}

Rest Global Exception Handling:

StudentErrorResponse.java

package com.luv2code.demo.rest;

public class StudentErrorResponse {

    private int status;
    private String message;
    private long timeStamp;

    public StudentErrorResponse() {

    }

    public StudentErrorResponse(int status, String message, long timeStamp) {
        this.status = status;
        this.message = message;
        this.timeStamp = timeStamp;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public long getTimeStamp() {
        return timeStamp;
    }

    public void setTimeStamp(long timeStamp) {
        this.timeStamp = timeStamp;
    }
}

StudentNotFoundException.java

package com.luv2code.demo.rest;

public class StudentNotFoundException extends RuntimeException {

    public StudentNotFoundException(String message) {
        super(message);
    }

    public StudentNotFoundException(String message, Throwable cause) {
        super(message, cause);
    }

    public StudentNotFoundException(Throwable cause) {
        super(cause);
    }
}

StudentRestController.java

package com.luv2code.demo.rest;

import com.luv2code.demo.entity.Student;
import jakarta.annotation.PostConstruct;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;

@RestController
@RequestMapping("/api")
public class StudentRestController {

    private List<Student> theStudents;

    // define @PostConstruct to load the student data ... only once!

    @PostConstruct
    public void loadData() {

        theStudents = new ArrayList<>();

        theStudents.add(new Student("Poornima", "Patel"));
        theStudents.add(new Student("Mario", "Rossi"));
        theStudents.add(new Student("Mary", "Smith"));
    }


    // define endpoint for "/students" - return a list of students

    @GetMapping("/students")
    public List<Student> getStudents() {

        return theStudents;
    }

    // define endpoint or "/students/{studentId}" - return student at index

    @GetMapping("/students/{studentId}")
    public Student getStudent(@PathVariable int studentId) {

        // just index into the list ... keep it simple for now

        // check the studentId again list size

        if ( (studentId >= theStudents.size()) || (studentId < 0)) {
            throw new StudentNotFoundException("Student id not found - " + studentId);
        }

        return theStudents.get(studentId);
    }
}

StudentRestExceptionHandler.java

package com.luv2code.demo.rest;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;


// Global Scope Exception Handler
@ControllerAdvice
public class StudentRestExceptionHandler {

    // add exception handling code here

    @ExceptionHandler
    public ResponseEntity<StudentErrorResponse> handleException(StudentNotFoundException exc) {

        // create a StudentErrorResponse

        StudentErrorResponse error = new StudentErrorResponse();

        error.setStatus(HttpStatus.NOT_FOUND.value());
        error.setMessage(exc.getMessage());
        error.setTimeStamp(System.currentTimeMillis());

        // return ResponseEntity

        return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
    }

    // add another exception handler ... to catch any exception (catch all)

    @ExceptionHandler
    public ResponseEntity<StudentErrorResponse> handleException(Exception exc) {

        // create a StudentErrorResponse
        StudentErrorResponse error = new StudentErrorResponse();

        error.setStatus(HttpStatus.BAD_REQUEST.value());
        error.setMessage(exc.getMessage());
        error.setTimeStamp(System.currentTimeMillis());

        // return ResponseEntity
        return new ResponseEntity<>(error, HttpStatus.BAD_REQUEST);
    }
}

💫The End 💫