Bean Validation Framework

This framework implemented get rid of validate bean object using if-else condition and easy to integrate custom validators.
– This is developed using Java 1.5 and no other library is required.
– Used Generics,Reflection and Annotation in implementation.
– Light weight Annotation base bean validation with runtime plugable custom validators.No need to register custom validator it adds automatically at runtime.
– easy to add custom validators.
– It can be use as standalone at presentation layer.

Note: validation annotation applied only to bean property fields.
-In custom validator implementation , add message field to Annotation interface.

You can download code from github(git://github.com/jiren/BeanValidation.git).

Sample bean validation code using this framework.

public class MyBean {

   @MaxLength(value = 10, message = "Max length of name field is 10.")
   private String name;
   @Email(message="Please Enter valid email in format abc@xyz.com")
   private String email;

   public String getEmail() {
             return email;
   }

   public void setEmail(String email) {
            this.email = email;
   }

   public String getName() {
           return name;
   }

   public void setName(String name) {
          this.name = name;
   }

   public static void main(String[] args) {
          MyBean myBean = new MyBean();
          myBean.setName("name");
          myBean.setEmail("abcxyz.com");
          //Validation
          VMessages vm = BeanValidator.validate(myBean);
          //Print Validation Message
         for (Iterator it = vm.getMessages().iterator(); it.hasNext();) {
                System.out.println(it.next());
          }
    }
}

=>
Minimum length annotation implementation.Here @AValidation indicate which class going to validate annotated field.It used to identify whether the annotation is validation annotation or not.

@AValidation(validator = com.validation.validators.MinLengthValidator.class)
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface MinLength {
    int value();
    String message();
}

=> IValidator interface : Here ‘ T ‘ generic field type which is going to validate using ‘ A’ validation annotation. Here generic interface used to avoid casting object every time for different validators.

public interface IValidator {
      public boolean validate(T value, A annotation, VMessages validationMsges);
}

=> Minimum length validator implementation. Here VMessages is store constrain violation messages.

public class MinLengthValidator implements IValidator {
     public boolean validate(String value, MinLength aMinLength, VMessages validationMsg) {

         if (value != null) {
             if (value.length() &lt; aMinLength.value()) {
                   validationMsg.addMessage(aMinLength.message());
                   return false;
             }
            return true;
        }
      else{
          validationMsg.addMessage(aMinLength.message());
          return false;
      }
   }
}