udao | Youdao translate base Angular | Server Side Rendering library

First, forgive my poor English, I am just working hard on my English:).

I'm trying to find an easy way to set the communication more simple between front-end and back-end, because I use ActiveMQ as the Message Oriented Middleware. So XML string became the request carrier.

For example, front-end send a string request to back-end including package name, class name, method name and parameters list, in this way, back-end is allowed to invoke the correct method by these information, and send invoke result back to front-end. It works, but not perfect. The problem is that when I tried to invoke a method in a service class with @Transational and @Service annotation(which is the common practice to connect to the database),the transaction seemed not being opened, request and response are both received, just left a lot of sleeping connection in mysql database process, as much as the ActiveMQ's consumers every time.

Target method in service class:

I am trying to build a simple registration and login using Spring framework 5. And I am trying to avoid xml configuration by implementing java config classes. I don't want to use hibernate yet because i would like to learn to make it work with spring jdbc first before i use the easy but advance hibernate. I have tried to load database credentials from property file.

I am getting this exception after i submit registration form.

I have tried to display the errors using println method and logger but it is not showing for some reason I need to figure out. So here are two things

1. Not able to find exactly what is creating NullpointerException because it says it is nested Exception. I think it is database connection which is causing this problem and I am confused why I am not having SQLDriver Class not found exception if it is database connection.

2. Why am i not able to display output of variables causing null exception and Why is my logger implementation not displaying any details of errors.

I have tried various methods to solve it but wasted long time due to failure to make it work. Hence, I am here for expert's help.

I think something is not going well with how i tried to load database credentials to make database connection works as datasource is still null i guess hence i would like to know How to load database credential from property file using java config class (not xml approach) and use it in DAO?

database-properties.properties

For the project that we create during my formation we use spring to make dependency injection.

we have a servlet-context.xml file with the following configuration:

I'm working on a project of package deliveries in Java.

I'm attempting to load two JComboBox components with data from a database and I'm getting the following errors.

i am creating simple rest api using jersey and here i assigned all the data fetched from database to variables and then return those variables data as list but i get an error. i have seen other examples but i don't get it whats wrong here is what i did:

I wrote it as a singleton before, there were no errors. But I think I should make it instance per request. And I have the code

I'm attempting to make a login system by using a model and DAO class to write users to a file called users.txt

In my controller, I created an initialize method: