csv 파일 생성 예제. (추가 라이브러리 없이)

csv 파일 생성 샘플.

주로 public get 메소드의 값으로 csv 파일을 생성하기 위한 것.

 

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

/*
 * Csv 파일 양식 파일을 생성한다.
 */
public class CsvWriter {

	private String csvDelimeter = "\t";
	private String lineSeparator = System.lineSeparator();
	private String methodPrefix = "";
	private Pattern patternCols = null;

	@SuppressWarnings("rawtypes")
	private Class writeClass = Object.class;

	@SuppressWarnings("rawtypes")
	public CsvWriter(Class clz, String csvDelimeter, String lineSeparator, String methodPrefix) {
		this.writeClass = clz;
		this.csvDelimeter = csvDelimeter;
		this.lineSeparator = lineSeparator;
		this.methodPrefix = methodPrefix;
	}

	@SuppressWarnings("rawtypes")
	public CsvWriter(Class clz, String methodPrefix) {
		this.writeClass = clz;
		this.methodPrefix = methodPrefix;
	}

	@SuppressWarnings("rawtypes")
	public CsvWriter(Class clz, String methodPrefix, String regexpIncludeCols) {
		this.writeClass = clz;
		this.methodPrefix = methodPrefix;
		if(regexpIncludeCols != null) {
			this.patternCols = Pattern.compile(regexpIncludeCols, Pattern.CASE_INSENSITIVE); // 대소문자 무시
		}
	}

	/**
	 * Csv 파일 양식 파일을 생성한다.
	 * <pre>
	 * 		String filePath = "C:\\output.csv";
	 *		List<Object> objectList = list.stream()
	 *								.map(m -> (Object)m)
	 *								.collect(Collectors.toList());
	 *		String regexpColsName = "id|name";
	 *		CsvWriter csv = new CsvWriter(클래스.class, "get", regexpColsName);
	 *		csv.writeObjectToCsv(filePath, objectList);
	 * </pre>
	 * @param filePath
	 * @param list
	 */
	public void writeObjectToCsv(String filePath, List<Object> list) {

		List<Method> methodlist = listgetMethod(writeClass);

		StringBuilder sb = new StringBuilder(1000);
		sb.append(getColNames(methodlist, csvDelimeter));
		for(Object lot : list) {
			sb.append(lineSeparator).append(getColValues(methodlist, lot, csvDelimeter));
		}

		// log.info(sb.toString());

		writeCSV(filePath, sb.toString());
	}

	public String getColNames(List<Method> list, String csvDelimeter) {
		StringBuilder sb = new StringBuilder(200);

		for(int i = 0; i < list.size(); i++) {
			if(i > 0)
				sb.append(csvDelimeter);
			sb.append(list.get(i).getName().substring(3)); // get 이후
		}

		return sb.toString();
	}

	public String getColValues(List<Method> list, Object obj, String csvDelimeter) {
		StringBuilder sb = new StringBuilder(200);

		String EMPTY = "";
		for(int i = 0; i < list.size(); i++) {
			if(i > 0)
				sb.append(csvDelimeter);

			try {
				Object returnObj = list.get(i).invoke(obj);
				if(returnObj != null)
					sb.append(returnObj.toString());
				else
					sb.append(EMPTY);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}

		return sb.toString();
	}

	@SuppressWarnings("rawtypes")
	public List<Method> listgetMethod(Class clz) {
		List<Method> list = new ArrayList<>();
		for (Method method : clz.getMethods()) {
			if(!Modifier.isPublic(method.getModifiers())) // public 아니면 skip
				continue;

			if(methodPrefix != null && methodPrefix.length() > 0 && !method.getName().startsWith(methodPrefix)) // prefix와 같지 않으면 skip
				continue;

			if(patternCols != null) {
				String colName = methodPrefix == null? method.getName() : method.getName().substring(methodPrefix.length());
				if(!this.patternCols.matcher(colName).find()) // colume 목록와 매칭되지 않으면 skip
					continue;
			}

			Class returnClass = method.getReturnType();
			if(returnClass.isPrimitive() || method.getReturnType() == String.class || method.getReturnType() == Long.class || method.getReturnType() == Integer.class) {
				list.add(method);
			}
		}

		list = list.stream().sorted(Comparator.comparing(Method::getName)).collect(Collectors.toList());

		return list;
	}

	public void writeCSV(String filePath, String contents) {
		BufferedWriter writer = null;
        try {
        	int BUFFER_SIZE = 1024 * 20;
            FileOutputStream out = new FileOutputStream(new File(filePath));
            writer = new BufferedWriter(new OutputStreamWriter(out, "EUC-KR"), BUFFER_SIZE);
            writer.write(contents);
        } catch (IOException e) {
            throw new IllegalStateException("Can't create writer ", e);
        } finally {
			try {
				if(writer != null)
					writer.close();
			} catch (IOException e) {
			}
        }
	}
}