JAVA 프로젝트 시작 방법

* JDK 설치
https://www.oracle.com/kr/java/technologies/downloads

https://aws.amazon.com/corretto

설치후 "where java" 명령으로 경로 설정 확인
설치된 곳이 "C:\Program Files\Java\jdk-21" 라면
"C:\Program Files\Java\jdk-21\bin" 폴더를 환경변수 PATH 에 경로 설정
setx JAVA_HOME "C:\Program Files\Java\jdk-21"
setx PATH "%PATH%;%JAVA_HOME%\bin"

* Maven 설치
https://maven.apache.org/
프로젝트 관리 : 빌드, 실행, 테스트
압축풀고 환경변수  PATH 에 경로 설정

//-------------------------------------

* vscode extension 설치

Extension Pack for Java

//-----------------------------------------------------------------------------
4개 파일 생성
//-------------------------------------
// src/main/java/com/example/App.java - 메인 클래스
package com.example;
public class App {
    public static void main(String[] args) {
        System.out.println("hello world");
    }
}

//-------------------------------------
// .vscode/launch.json
{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "java",
            "name": "Debug App",
            "request": "launch",
            "mainClass": "cohttp://m.example.App",
            "projectName": "ex1"
        }
    ]
}
//-------------------------------------
// .vscode/settings.json
{
    "java.project.sourcePaths": [ "src/main/java" ],
    "java.project.outputPath": "bin",
    "java.project.referencedLibraries": [
        "lib/**/*.jar"
    ]
}

//-------------------------------------
// pom.xml  - Maven 프로젝트 파일

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.example</groupId>
<artifactId>프로젝트이름</artifactId>
<version>1.0</version>

<properties>
<maven.compiler.source>11</maven.compiler.source>
<maven.compiler.target>11</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>

</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>3.3.0</version>
<configuration>
<archive>
<manifest>
<mainClass>com.example.App</mainClass>
<addClasspath>true</addClasspath>
</manifest>
</archive>
</configuration>
</plugin>

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.5.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>

<configuration>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>com.example.App</mainClass>
</transformer>
</transformers>
</configuration>

</execution>
</executions>
</plugin>

</plugins>
</build>

</project>

//-----------------------------------------------------------------------------

* 실행 방법1 : 
vscode 에서 Run -> Start Debugging (F5) 선택

//-------------------------------------
* 실행 방법2 : java 사용
# 컴파일
javac -d bin src/main/java/com/example/*.java src/main/java/com/example/util/*.java

# 실행
java -cp bin cohttp://m.example.App

//-------------------------------------
실행 방법3 :  Maven 사용

# 컴파일
mvn compile

# 실행
mvn exec:java -Dexec.mainClass="cohttp://m.example.App"

# 테스트
mvn test

# 실행용 압축파일 JAR 생성 (컴파일도 실행)
mvn package

실행
java -jar target/myapp.jar