java Tip

날짜 연산

https://codechacha.com/ko/java-examples-add-two-dates/

Java - Date에 년,월,일을 더하고 빼는 방법

String day = "20220101";

DateFormat df = new SimpleDateFormat("yyyyMMdd");
							
try {
	Calendar cal = Calendar.getInstance();
	cal.setTime(df.parse(day));
	cal.add(Calendar.DATE, 1);
	day = df.format(cal.getTime());
} catch(ParseException e) {
	e.printStackTrace();
}

문자열 날짜형으로 변경

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHH:mm:ss");
String strDate = day + time;
Instant date = null;

try {
	date = sdf.parse(strDate).toInstant();
} catch(ParseException e) {
	e.printStackTrace();
}

Spring Boot에서 system properties 값 참조하기

java -jar -Dtest=xxxx Application.jar

public class Application {

	@Value("${test}")
	String test;
	
	@GetMapping("/")
	String home() {
		System.out.println(test);
		return "Spring is here!";
	}

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
		System.out.println("Start!");
	}
}

Spring Boot에서 appliation.properties 변수 참조하기

https://kim-jong-hyun.tistory.com/17

[Spring] - properties파일에 정의된 값들 JAVA에서 조회

# static으로 선언하면 값을 가져오지 못함

	@Value("${quarts.schedule}")
	private static String schedule;
    
	@GetMapping("/")
	String home() {
		logger.info("Quartz Schedule: " + schedule);
		return "Spring is here!";

결과

Quartz Schedule: null

logback 사용시, 아래 구문이 빠지면 아래 부분이 작동을 하지 않음

환경설정파일 적용 안됨

콘솔은 잘되나, 파일로 로깅하는 것은 안됨

main 함수에 꼭 필요한 내용

SpringApplication.run(ProcessKill.class, args);

log4j2 셋팅

https://velog.io/@bread_dd/Log4j-2-%EC%A0%9C%EB%8C%80%EB%A1%9C-%EC%82%AC%EC%9A%A9%ED%95%98%EA%B8%B0-%EA%B0%9C%EB%85%90

Log4j 2 제대로 사용하기 - 개념

https://tlatmsrud.tistory.com/31

[Spring] log4j2 사용법, 로그남기기, 파일 저장

pom.xml

		<!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-slf4j-impl -->
		<dependency>
		    <groupId>org.apache.logging.log4j</groupId>
		    <artifactId>log4j-slf4j-impl</artifactId>
		    <version>2.17.2</version>
		</dependency>

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>

<Configuration>
    <Properties>
        <Property name="logNm">rolling</Property>
        <Property name="layoutPattern">%style{%d{yyyy/MM/dd HH:mm:ss,SSS}}{cyan} %highlight{[%-5p]}{FATAL=bg_red, ERROR=red,
            INFO=green, DEBUG=blue}  [%C] %style{[%t]}{yellow}- %m%n</Property>
    </Properties>
    
	<!-- 로그 출력 방식 -->
	<Appenders>
    	<!-- 콘솔 출력 방식 -->
		<Console name="console-log" target="SYSTEM_OUT">
			<PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n" />
		</Console>
        <!-- 파일 저장 방식 -->
        <File name="file" fileName="./logs/processKill.log">
              <PatternLayout pattern="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
        </File>	
        <RollingFile name="rollingFile" fileName="./logs/${logNm}.log" filePattern="./logs/${logNm}_%d{yyyy-MM-dd}_%i.log.gz">
            <PatternLayout pattern="${layoutPattern}"/>
            <Policies>
                <SizeBasedTriggeringPolicy size="300KB"/>
                <TimeBasedTriggeringPolicy interval="1"/>
            </Policies>
            <DefaultRolloverStrategy max="10" fileIndex="min"/>
        </RollingFile>
	</Appenders>
    	
	<Loggers>
		<Logger name="moniter.PrinterClient" level="DEBUG"></Logger>
		<Root level="DEBUG">
			<appender-ref ref="console-log" level="DEBUG" />
			<appender-ref ref="file" level="INFO" />
			<appender-ref ref="rollingFile" level="INFO" />
		</Root>
	</Loggers>
</Configuration>
    	
	<Loggers>
		<Logger name="moniter.PrinterClient" level="DEBUG"></Logger>
		<Root level="DEBUG">
			<appender-ref ref="console-log" level="DEBUG" />
			<appender-ref ref="file" level="INFO" />
		</Root>
	</Loggers>
</Configuration>

한글깨짐 문제 찾기

https://pkss.tistory.com/entry/JAVA-%ED%95%9C%EA%B8%80%EA%B9%A8%EC%A7%90-%ED%95%9C%EB%B0%A9%EC%97%90-%EC%B0%BE%EA%B8%B0

[JAVA] 한글깨짐 한방에 찾기

				System.out.println("-->" + new String(e.getMessage().getBytes("UTF-8"), "EUC-KR"));
				System.out.println("-->" + new String(e.getMessage().getBytes("UTF-8"), "KSC5601"));
				System.out.println("-->" + new String(e.getMessage().getBytes("UTF-8"), "x-windows-949"));
				System.out.println("-->" + new String(e.getMessage().getBytes("UTF-8"), "iso-8859-1"));
				System.out.println("-->" + new String(e.getMessage().getBytes("KSC5601"), "EUC-KR"));
				System.out.println("-->" + new String(e.getMessage().getBytes("KSC5601"), "UTF-8"));
				System.out.println("-->" + new String(e.getMessage().getBytes("KSC5601"), "x-windows-949"));
				System.out.println("-->" + new String(e.getMessage().getBytes("KSC5601"), "iso-8859-1"));
				System.out.println("-->" + new String(e.getMessage().getBytes("x-windows-949"), "EUC-KR"));
				System.out.println("-->" + new String(e.getMessage().getBytes("x-windows-949"), "KSC5601"));
				System.out.println("-->" + new String(e.getMessage().getBytes("x-windows-949"), "UTF-8"));
				System.out.println("-->" + new String(e.getMessage().getBytes("x-windows-949"), "iso-8859-1"));
				System.out.println("-->" + new String(e.getMessage().getBytes("iso-8859-1"), "EUC-KR"));
				System.out.println("-->" + new String(e.getMessage().getBytes("iso-8859-1"), "KSC5601"));
				System.out.println("-->" + new String(e.getMessage().getBytes("iso-8859-1"), "x-windows-949"));
				System.out.println("-->" + new String(e.getMessage().getBytes("iso-8859-1"), "UTF-8"));
				System.out.println("-->" + new String(e.getMessage().getBytes("EUC-KR"), "UTF-8"));
				System.out.println("-->" + new String(e.getMessage().getBytes("EUC-KR"), "KSC5601"));
				System.out.println("-->" + new String(e.getMessage().getBytes("EUC-KR"), "x-windows-949"));
				System.out.println("-->" + new String(e.getMessage().getBytes("EUC-KR"), "iso-8859-1"));

Quartz 변수 넘기기

https://huikyun.tistory.com/231

[Quartz]Quartz에서 작업 클래스로 파라미터 넘기기...

변수 셋팅

		JobDetail jobDetail = JobBuilder.newJob(DashboardDataJob.class)
				.build();
		CronTrigger trigger = (CronTrigger)TriggerBuilder.newTrigger()
				.withSchedule(CronScheduleBuilder.cronSchedule(schedule))
				.build();
		
		JobDataMap jobDataMap = jobDetail.getJobDataMap();
		jobDataMap.put("port", port);

변수 사용하기

public class DashboardDataJob implements Job {

	private static Logger logger = LoggerFactory.getLogger(DashboardDataJob.class);
	
    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
    	logger.info("DashboardDataJob Start");
    	JobDataMap jobDataMap = context.getMergedJobDataMap();
    	String port = jobDataMap.getString("port");
		String value = "http://localhost:"+ port +"/insert";
		logger.info("URL: "+ value);

		try {
			URL url = new URL(value);
			InputStream is = url.openStream();
			is.close();
		} catch (java.io.IOException e) {
			// TODO Auto-generated catch block
			logger.error("execute() Except", e);
		}

	   	logger.info("DashboardDataJob End");
    }
}

JVM TimeZone 설정

http://daplus.net/java-jvm-timezone%EC%9D%84-%EC%98%AC%EB%B0%94%EB%A5%B4%EA%B2%8C-%EC%84%A4%EC%A0%95%ED%95%98%EB%8A%94-%EB%B0%A9%EB%B2%95/

[java] JVM TimeZone을 올바르게 설정하는 방법 - 리뷰나라

OS의 TimeZone과 JVM의 TimeZone이 다를 경우, 조치하는 방법

1. 실행시 옵션 적용

java -Duser.timezone="Asia/Seoul" -jar abc.jar

2. 환경변수 설정

export TZ="Asia/Seoul"

JAVA_OPTS 처리하기

https://whoa0987.tistory.com/37

[JBoss EAP 7.2] 소스 내 properties 대신 서버 JAVA_OPTS 환경변수 사용하는 법

	# JAVA_OPTS 셋팅
    -DrootDir=/bac/bbb/
    
    # JAVA_OPTS 변수 가져오기
    public ImageManager(String dir) {
		ImagePath.add(System.getProperty("rootDir") + dir);	
	}

Maven에서 resource 복사하기(이미지, jar 등)

http://daplus.net/maven-maven%EC%9C%BC%EB%A1%9C-%ED%8C%8C%EC%9D%BC%EC%9D%84-%EB%B3%B5%EC%82%AC%ED%95%98%EB%8A%94-%EB%AA%A8%EB%B2%94-%EC%82%AC%EB%A1%80/

[maven] Maven으로 파일을 복사하는 모범 사례 - 리뷰나라

jar 파일안의 jar, image 등은 접근이 안되기 때문에 디렉토리에 복사하여 참조하도록 함

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-jar-plugin</artifactId>
				<version>3.2.0</version>
				<configuration> 
					<archive> 
						<manifest> 
						    <addClasspath>true</addClasspath>
							<mainClass>lok.Lok</mainClass> 
							<addClasspath>true</addClasspath>
							<classpathPrefix>resources/libs/</classpathPrefix>
						</manifest> 
					</archive> 
				</configuration>
			</plugin>
			<plugin> 
				<groupId>org.apache.maven.plugins</groupId> 
				<artifactId>maven-dependency-plugin</artifactId> 
				<version>3.2.0</version> 
				<executions> <execution> 
					<id>copy-dependencies</id> 
					<phase>package</phase> 
					<goals> 
						<goal>copy-dependencies</goal> 
					</goals>
					<configuration>
						<includeScope>runtime</includeScope> 
						<outputDirectory>${project.build.directory}/resources/libs/</outputDirectory> 
					</configuration> 
				</execution> 
			</executions> 
		</plugin>
		<plugin>
            <artifactId>maven-resources-plugin</artifactId>
            <version>3.2.0</version>
            <executions>
                <execution>
                    <id>copy-resource-one</id>
                    <phase>install</phase>
                    <goals>
                        <goal>copy-resources</goal>
                    </goals>

                    <configuration>
                        <outputDirectory>${basedir}/target/resources</outputDirectory>
                        <resources>
                            <resource>
                                <directory>src/main/resources</directory>
                                <includes>
                                    <include>*/**</include>
                                </includes>
                            </resource>
                        </resources>
                    </configuration>
                </execution>
           </executions>
        </plugin>
		</plugins>
	</build>

String.split 사용시 유의점

String[] split(String regex)은 입력값은 정규식이기 때문에 주의해야 함

String temp = "abc.txt".split(".");
System.out.println(temp);

위의 결과는 '0'임

정규식으로 인식하기 때문에 '.split("\\.")'으로 표현해야 함