Spring MVC Validation
In spring mvc, we can utilize JSR 303 and JSR 380 specification to make validation easier.
Note: If you already depend on spring-boot-starter-web, then you already have Spring Validation.
Otherwise, you’ll have to include spring-context.
Code
Bean
import java.io.Serializable;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
public class User implements Serializable{
private static final long serialVersionUID = -7561411960266528475L;
@NotNull(message = "id cannot be null")
@Min(1)
private Integer userId;
@NotNull
@Size(min = 1,max = 3, message = "use name length must be between 1 and 3")
private String userName;
public Integer getUserId() {
return userId;
}
public void setUserId(Integer userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
}
Result Message
public class ResultMessage {
private boolean isSuccess;
private String code;
private String msg;
public boolean isSuccess() {
return isSuccess;
}
public void setSuccess(boolean isSuccess) {
this.isSuccess = isSuccess;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
Controller
@RequestMapping("getUser")
public User getUser(@RequestBody @Valid User user) {
return this.userService.getUser(user.getUserId());
}
@Valid and @Validated
@Validated was added to support “validation groups”. For example,
@NotBlank(groups = {StepTwo.class})
private String name;
@Email(groups = {StepOne.class})
private Stirng email;
@RequestMapping(value = "stepOne")
public String stepOne(@Validated(User.StepOne.class) User user) {//...}
Exception Handler
import java.util.List;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;
import com.example.sb.model.ResultMessage;
import org.springframework.http.HttpStatus;
import org.springframework.validation.ObjectError;
@ControllerAdvice
public class CustomExceptionHandler {
@ResponseStatus(HttpStatus.BAD_REQUEST)
@ExceptionHandler(MethodArgumentNotValidException.class)
public @ResponseBody ResultMessage handleValidationExceptions(MethodArgumentNotValidException ex) {
List<ObjectError> errors = ex.getBindingResult().getAllErrors();
ResultMessage result = new ResultMessage();
StringBuilder sb = new StringBuilder();
for(ObjectError err : errors ) {
sb.append(err.getDefaultMessage());
}
result.setSuccess(false);
result.setCode("Validate failed");
result.setMsg(sb.toString());
return result;
}
@ExceptionHandler(ConstraintViolationException.class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
public @ResponseBody ResultMessage handle(ConstraintViolationException exception) {
//.....
}
}
Note: @Valid annotation results in MethodArgumentNotValidException being thrown when validation fails, but @Validated results in ConstraintViolationException being thrown.
@ExceptionHandler
It is used to handle exceptions and errors by annotating it on a method.
Developer can create a method within a controller with this annotation to handle exception.
If you want to apply this logic to all controllers, you should create a new class annotated with the @ControllerAdvice