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We will start by making Controller that doesn't use Service.
● Instead business logic is implemented inside the Controller itself.
● In our example business logic is to return "Hello" String.
● Such approach is not ideal because each Class should do one thing and one thing only.
But in this case Controller does two things
● accepts incoming HTTP Requests
● implements business logic
This causes following problems
● Application becomes harder to maintain and test since everything is in one Class
● Controller becomes big and unreadable by having all of the business logic placed inside its end points.
● To change business logic we need to change the Controller potentially introducing bugs which might
○ affect its main purpose of routing HTTP Requests
○ affect other parts of business logic if Controller becomes corrupted
Application Schema [Results]
Spring Boot Starters
GROUP
DEPENDENCY
DESCRIPTION
Web
Spring Web
Enables: @Controller, @RequestMapping, Tomcat Server
hello()
MyController
http://localhost:8080/Hello
Tomcat
Browser
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Create Project: springboot_service_controller (add Spring Boot Starters from the table)
Create Package: controllers (inside main package)
– Create Class: MyController.java (inside package controllers)
MyController.java
package com.ivoronline.springboot_service_controller.controllers;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
public class MyController {
@ResponseBody
@RequestMapping("/Hello")
public String hello() {
//BUSINESS LOGIC
String result = "Hello from Controller";
//RETURN RESULT
return result;
}
}
