dateutils.java.svn-base

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package org.derrick.util;

import java.text.DateFormat;
import java.util.Calendar;

import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
/**
 * 
 * @author 刘冬宝Oct 26, 2006
   版权申明：所有人员均可自由修改源码并再发布，但必须保留此相关信息
 *
 */
public class DateUtils {
	protected static Logger logger = LogManager.getLogger(DateUtils.class);

	/**
	 * 
	 * @param srcDate
	 *            200404
	 * @return 200403
	 * @throws Exception
	 */
	public static String subtractOneMonth(String srcDate) throws Exception {
		if (srcDate == null || srcDate.length() < 6) {
			logger.error(srcDate);
			throw new RuntimeException("srcDate 格式不合！");
		}
		if (logger.isDebugEnabled()) {
			logger.debug("before开始年月:" + srcDate);
		}
		DateFormat df = DateFormat.getDateInstance();
		StringBuffer buffer = new StringBuffer();
		buffer.append(srcDate.substring(0, 4));
		buffer.append("-");
		buffer.append(srcDate.substring(4, 6));
		buffer.append("-");
		buffer.append("01");
		df.parse(buffer.toString());
		Calendar calendar = df.getCalendar();
		calendar.add(Calendar.MONTH, -1);
		String result = String.valueOf(calendar.get(Calendar.YEAR))
				+ StringUtils.leadingZero(String.valueOf(calendar
						.get(Calendar.MONTH) + 1), 2);
		if (logger.isDebugEnabled()) {
			logger.debug("convert开始年月:" + result);
		}

		return result;

	}
	// static void test(){
	// StringBuilder builder = new StringBuilder();
	// builder.append("s")
	// }
}