Spring

• — What is Spring?
  • — A framework to build servers in Java with dependency injection
  • — What is a server?
    • — Something that listens to on a network port, receives inputs, proceses and sends output back on the port
• — Dependency injection
  • — Why?
    • — Objects depend on many other objects
    • — When you use constructors of Java you get into a mess
    • — Example issues
  • — How it works?
    • — You define classes as beans and what they need
    • — In the main function of the Java program, you initialize Spring containers
    • — Spring container creates objects that are needed by reading the configuration in the runtime files
    • — The initialized beans in the Spring runtime has access to the things they need
    • — You want some bean, you can ask from runtime (but not really used)
    • — Spring has an elaborate initialization logic
    • — Spring can load lots of things, based on what is available in the runtime
      • — If something is a maven dependency
• — Common component
  • — Controller
    • — When spring initializer sees one, it adds the route conriguration to its routing system nad forward the requests
    • — It can map the variables
  • — Repositories
    • — You just tell what Entity (Plan Old Java Object) and Spring loads the beans that are Data Access Objecgts
  • — Database connection
    • — Spring reads the database configurations and establishes connections and injects access references
  • — Security
    • — You give pieces of configurations as beans. Spring uses them and gives them to its own beans.
• — Ways of configuring
  • — properties files
    • — Different files for different profiles
      • — Profiles are dev, production, testing etc.
    • — Beans
      • — @Service, @Controller
    • — Just add libraries to pom.xml