Property Source not getting autowired - spring-boot

Question

I am using external property sources for some reason one of the external property source is not getting autowired, receiving null pointer while creating the authenticaion bean
Error Message
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.filechecker.check.Authenticator]: Constructor threw exception; nested exception is java.lang.NullPointerException
Caused by: java.lang.NullPointerException: null
at com.filechecker.check.Authenticator.(Authenticator.java:30) ~[classes!/:0.0.1-SNAPSHOT]
Line no 30:
String username = emailPropertyConfig.getEmailConfig().getUsername();
not working one
#Component
#PropertySource(value="${email.app.properties}",ignoreResourceNotFound = false)
#ConfigurationProperties
public class PropertyEmailConfiguration {
private EmailConfig emailConfig = new EmailConfig();
public EmailConfig getEmailConfig() {
return emailConfig;
}
public void setEmailConfig(EmailConfig emailConfig) {
this.emailConfig = emailConfig;
}
}
#Component
public class Authenticator extends javax.mail.Authenticator {
#Autowired
PropertyEmailConfiguration emailPropertyConfig;
#Autowired
CipherCrypt cipherCrypt;
private PasswordAuthentication authentication;
public Authenticator() throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException {
String username = emailPropertyConfig.getEmailConfig().getUsername();
String password = cipherCrypt.decrypt(emailPropertyConfig.getEmailConfig().getEncryptPassword());
authentication = new PasswordAuthentication(username, password);
}
#Override
protected PasswordAuthentication getPasswordAuthentication() {
return authentication;
}
}
working one
#Component
#PropertySource(value="${external.app.properties}", ignoreResourceNotFound = true)
#ConfigurationProperties
public class PropertyConfiguration {
private List<FileStructureConfig> fileStructureConfig = new ArrayList();
private List<EmailSendingProperties> emailSendingProperties = new ArrayList();
public List<FileStructureConfig> getFileStructureConfig() {
return fileStructureConfig;
}
public void setFileStructureConfig(List<FileStructureConfig> fileStructureConfig) {
this.fileStructureConfig = fileStructureConfig;
}
public List<EmailSendingProperties> getEmailSendingProperties() {
return emailSendingProperties;
}
public void setEmailSendingProperties(List<EmailSendingProperties> emailSendingProperties) {
this.emailSendingProperties = emailSendingProperties;
}
}

Answer 1

You are trying to access an #Autowired property within the constructor. The property cannot be autowired at this stage.
In order for Spring to "bake the bean", Spring has to create your object (using your constructor), and only afterwards it applys the autowiring mechanism to inject emailPropertyConfig and cipherCrypt. Therefore you cannot access the two #Autowired properties within the constructor.
If you need to extract some values from the emailPropertyConfig or cipherCrypt you can do it in #PostConstruct
#Component
public class Authenticator {
#Autowired
PropertyEmailConfiguration emailPropertyConfig;
#Autowired
CipherCrypt cipherCrypt;
private PasswordAuthentication authentication;
#PostConstruct
void init() throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException {
String username = emailPropertyConfig.getEmailConfig().getUsername();
String password = cipherCrypt.decrypt(emailPropertyConfig.getEmailConfig().getEncryptPassword());
authentication = new PasswordAuthentication(username, password);
}
#Override
protected PasswordAuthentication getPasswordAuthentication() {
return authentication;
}
}
or use constructor injection:
#Component
public class Authenticator {
PropertyEmailConfiguration emailPropertyConfig;
CipherCrypt cipherCrypt;
private PasswordAuthentication authentication;
public Authenticator(PropertyEmailConfiguration emailPropertyConfig, CipherCrypt cipherCrypt) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException {
String username = emailPropertyConfig.getEmailConfig().getUsername();
String password = cipherCrypt.decrypt(emailPropertyConfig.getEmailConfig().getEncryptPassword());
authentication = new PasswordAuthentication(username, password);
}
#Override
protected PasswordAuthentication getPasswordAuthentication() {
return authentication;
}
}