我的工具类

1：将带宽流量转换单位

package com.chinacache.snp.TransferChannelAlarm.util;

import java.text.DecimalFormat;
import java.text.Format;

public class FormatToSuitableFluxUnit {
	private static final long K_BIT = 1000;
	private static final long M_BIT = 1000 * 1000;
	private static final long G_BIT = 1000 * 1000 * 1000;
	
	private static final long T_BIT = 1000 * 1000 * 1000 * 1000L;
	private static final long P_BIT = 1000 * 1000 * 1000 * 1000L * 1000L;
	private static final long E_BIT = 1000 * 1000 * 1000 * 1000L * 1000L * 1000L;

	public static final String BIT_STR = "Byte";
	public static final String K_BIT_STR = "KB";
	public static final String M_BIT_STR = "MB";
	public static final String G_BIT_STR = "GB";
	public static final String T_BIT_STR = "TB";
	public static final String P_BIT_STR = "PB";
	public static final String E_BIT_STR = "EB";

	/**
	 * 将以bit表示的带宽，转换为适合显示的带宽单位，精确到小数点后两位
	 */
	public static String getSuitableFluxRepresentation(long fluxInBit) {
		// 保留小数点后面两位
		Format format = new DecimalFormat("#.00");
		if (fluxInBit >= E_BIT) {
			return format.format((double) fluxInBit / E_BIT) + " " + E_BIT_STR;
		} else if (fluxInBit >= P_BIT) {
			return format.format((double) fluxInBit / P_BIT) + " " + P_BIT_STR;
		} else if (fluxInBit >= T_BIT) {
			return format.format((double) fluxInBit / T_BIT) + " " + T_BIT_STR;
		} else if (fluxInBit >= G_BIT) {
			return format.format((double) fluxInBit / G_BIT) + " " + G_BIT_STR;
		} else if (fluxInBit >= M_BIT) {
			return format.format((double) fluxInBit / M_BIT) + " " + M_BIT_STR;
		} else if (fluxInBit >= K_BIT) {
			return format.format((double) fluxInBit / K_BIT) + " " + K_BIT_STR;
		} else {
			return fluxInBit +"   "+ BIT_STR;
		}
	}

	/**
	 * 获取合适的带宽单位
	 */
	public static String getSuitableFluxUnit(long fluxInBit) {
		if (fluxInBit >= E_BIT) {
			return E_BIT_STR;
		} else if (fluxInBit >= P_BIT) {
			return P_BIT_STR;
		} else if (fluxInBit >= T_BIT) {
			return T_BIT_STR;
		} else if (fluxInBit >= G_BIT) {
			return G_BIT_STR;
		} else if (fluxInBit >= M_BIT) {
			return M_BIT_STR;
		} else if (fluxInBit >= K_BIT) {
			return K_BIT_STR;
		} else {
			return BIT_STR;
		}
	}
}

 2：对list分组（前n个list大小为groupSize）

package com.chinacache.snp.bill.datacontrast.util;

import java.util.ArrayList;
import java.util.List;

import org.apache.commons.collections.CollectionUtils;

public class GroupUtil {

	public static List<List<String>> divideIntoGroups(List<String> list, int groupSize) {
		if (CollectionUtils.isEmpty(list)) {
			return null;
		}

		List<List<String>> groups = new ArrayList<List<String>>();

		List<String> group = null;
		int totalSize = list.size();

		for (int i = 0; i < totalSize; i++) {
			if (i % groupSize == 0) {
				group = new ArrayList<String>();
				groups.add(group);
			}
			group.add(list.get(i));
		}
		return groups;
	}
}

 3：java时间区

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");         //格式日期
TimeZone timezone = TimeZone.getTimeZone("Asia/Shanghai");                //时区
sdf.setTimeZone(timezone );
System.out.println(sdf.format(new Date()));

 4：读取properties配置文件的常量类

    父类：

package com.chinacache.snp.TransferChannelAlarm.util;

import java.io.IOException;
import java.io.InputStream;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashSet;
import java.util.Properties;
import java.util.Set;

import org.apache.log4j.Logger;

/**
 * 常量配置类，从指定文件读取常量
 * 
 */
public class ConfigurableContants {

    private static final Logger logger = Logger.getLogger(ConfigurableContants.class);

    protected static Properties p = new Properties();

    protected static void init(String propertyFileName) {
        InputStream in = null;
        try {
            in = ConfigurableContants.class.getResourceAsStream(propertyFileName);
            if (in != null)
                p.load(in);
        } catch (IOException e) {
            logger.error("load " + propertyFileName + " into Contants error");
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                }
            }
        }
    }

    protected static String getProperty(String key, String defaultValue) {
        return p.getProperty(key, defaultValue);
    }

    protected static String getProperty(String key) {
        return getProperty(key, "");
    }

    /**
     * 取以","分割的集合属性
     *
     * @param key
     * @param defaultValue
     * @return
     */
    protected static Set<String> getSetProperty(String key, String defaultValue) {

        String[] strings = p.getProperty(key, defaultValue).split(",");
        HashSet<String> hashSet = new HashSet<String>(strings.length);
        for (String string : strings) {
            hashSet.add(string.trim());
        }
        return hashSet;
    }

    protected static Set<String> getSetProperty(String key) {
        return getSetProperty(key, "");
    }

    protected static Date getPropertyWithDateFormate(String key, String dateFormate) {
        String str = null;
        Date date = null;
        try {
            str = getProperty(key, "");
            date = new SimpleDateFormat(dateFormate).parse(str);
        } catch (ParseException e) {
            logger.error("Date [" + str + "] Error in Contants");
        }
        return date;
    }
}

 子类（每个配置文件一个子类）

package com.chinacache.snp.TransferChannelAlarm.util;

/**
 * 常量类，包括配置文件的常量和程序定义的常量
 * 
 */
public final class SystemConstants extends ConfigurableContants {

	static {
		init("/system.properties");
	}

	public static final String thresholdValue = getProperty("report.threshold", "1");
	public static final String channelState = getProperty("channel.state", "TEST,TRANSFER");
	public static final String topSize = getProperty("channel.top.n", "1000");

	public static final String mailServer = getProperty("email.server", "");
	public static final String addresserUser = getProperty("addresser.user", "");
	public static final String addresserPass = getProperty("addresser.pass", "");
	public static final String cc = getProperty("cc", "[email protected]");

	public static String getStringByKey(String key) {
		return getProperty(key);
	}
}

 properties配置文件

report.threshold=0

channel.top.n=100000000
#channel.state=COMMERCIAL,TRANSFER
channel.state=TEST,COMMERCIAL,TRANSFER
TEST=测试
TRANSFER=转走
COMMERCIAL=商用

email.server=corp.chinacache.com
addresser.user=
addresser.pass=
[email protected]