https://github.com/enginkaratas/java-sandbox

sandbox for java, my notes, tries
https://github.com/enginkaratas/java-sandbox

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sandbox for java, my notes, tries

• Host: GitHub
• URL: https://github.com/enginkaratas/java-sandbox
• Owner: EnginKARATAS
• Created: 2022-08-20T10:51:41.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2024-10-27T07:22:16.000Z (2 months ago)
• Last Synced: 2024-10-27T08:28:33.156Z (2 months ago)
• Language: Java
• Size: 2.93 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

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README

        
# notes about java, spring boot:

package com.example.demo;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication

@RestController

public class DemoApplication {

    public static void main(String[] args) {

    	SpringApplication.run(DemoApplication.class, args);

    }

    @GetMapping("/hello")

    public String hello(@RequestParam(value = "name", defaultValue = "World") String name) {

    	return String.format("Hello %s!", name);

    }

}

@RestController annotation tells Spring that this code describes an endpoint that should be made available over the web.

@GetMapping(“/hello”) tells Spring to use our hello() method to answer requests that get sent to the http://localhost:8080/hello address

@RequestMapping() = @RequestMapping(method=GET)

@RequestParam is telling Spring to expect a name value in the request, but if it’s not there, it will use the word “World” by default.

@SpringBootApplication is a convenience annotation that adds all of the following:

@Configuration: Tags the class as a source of bean definitions for the application context.

@EnableAutoConfiguration: Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings. For example, if spring-webmvc is on the classpath, this annotation flags the application as a web application and activates key behaviors, such as setting up a DispatcherServlet.

@ComponentScan: Tells Spring to look for other components, configurations, and services in the com/example package, letting it find the controllers.

MappingJackson2HttpMessageConverter is automatically chosen to convert the any object instance to JSON.

## build &run

./mvnw clean package //build a JAR file

java -jar target/demo-0.0.1-SNAPSHOT.jar //run JAR file

## what is classloader

Classloader: It is the subsystem of JVM that is used to load class files.