How to save and load encrypted value using custom annotation
I am new to Java custom annotations
I am developing a custom annotation that encrypts and decrypts a string and store it in a database using spring and mongodb and for encryption I am using jasypt.
I am not getting the exact procedure for this.
My code.
An object
public class Demo {
@Id
private Long id;
private String somethingPublic;
@EncryptDemo()
private String somethingPrivate;
//getter setter
}
custom annotation
@Target({ ElementType.METHOD, ElementType.FIELD })
@Retention(RetentionPolicy.RUNTIME)
public @interface EncryptDemo {
}
How do I add encryption behavior to custom annotation before I save the object.
Where should I add the encryption code that reflects my annotation when it is called.
I want to create a sleeper like annotation.
Any help would be appreciated. Thank you in advance.
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1 answer
Basically you need
- Create
AbstractMongoEventListener
to listen for eventsAfterConvertEvent
andBeforeSaveEvent
- Execute callbacks
org.springframework.util.ReflectionUtils.FieldCallback
to perform actions on these events - Register listener as Bean in Spring data mongodb config class
Listener:
public class EncryptionMongoEventListener extends AbstractMongoEventListener<Object> {
@Override
public void onBeforeSave(BeforeSaveEvent<Object> event) {
Object source = event.getSource();
DBObject dbObject = event.getDBObject();
ReflectionUtils.doWithFields(source.getClass(),
new EncryptCallback(source, dbObject),
ReflectionUtils.COPYABLE_FIELDS);
}
@Override
public void onAfterConvert(AfterConvertEvent<Object> event) {
Object source = event.getSource();
ReflectionUtils.doWithFields(source.getClass(),
new DecryptCallback(source),
ReflectionUtils.COPYABLE_FIELDS);
}
}
Encrypt callback:
class EncryptCallback implements FieldCallback {
private final Object source;
private final DBObject dbObject;
public EncryptCallback(final Object source, final DBObject dbObject) {
this.source = source;
this.dbObject = dbObject;
}
@Override
public void doWith(Field field)
throws IllegalArgumentException, IllegalAccessException {
if (!field.isAnnotationPresent(/* your annotation */.class)) {
return;
}
ReflectionUtils.makeAccessible(field);
String plainText = (String) ReflectionUtils.getField(field, source);
String encryptedValue = /* your encryption of plainText */;
// update the value in DBObject before it is saved to mongodb
dbObject.put(field.getName(), encryptedValue);
}
}
Decrypt callback:
class DecryptCallback implements FieldCallback {
private final Object source;
public DecryptCallback(Object source) {
this.source = source;
}
@Override
public void doWith(Field field)
throws IllegalArgumentException, IllegalAccessException {
if (!field.isAnnotationPresent(/* your annotation */.class)) {
return;
}
ReflectionUtils.makeAccessible(field);
String fieldValue = (String) ReflectionUtils.getField(field, source);
String decryptedValue = /* your decryption of fieldValue */;
// set the decrypted value in source Object
ReflectionUtils.setField(field, source, decryptedValue);
}
}
and finally register the listener as a Bean in your Spring Data mongodb configuration class
@Bean
public EncryptionMongoEventListener encryptionMongoEventListener() {
return new EncryptionMongoEventListener();
}
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