Android写日志文件类

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import android.util.Log;

/**
 * 带日志文件输入的，又可控开关的日志调试
 * 
 * @author Dsw
 * @version 1.0
 * @data 2012-2-20
 */
public class DswLog {
	private static char    LOG_TYPE='v';							// 输入日志类型，w代表只输出告警信息等，v代表输出所有信息
	private static Boolean LOG_SWITCH = true; 						// 日志文件总开关
	private static Boolean LOG_WRITE_TO_FILE = true;				// 日志写入文件开关
	
	private static int  SDCARD_LOG_FILE_SAVE_DAYS = 0;				// sd卡中日志文件的最多保存天数

	private static String LOGFILENAME = "Log.txt";					// 本类输出的日志文件名称
	private static String LOG_PATH_SDCARD_DIR = "/sdcard/";			// 日志文件在sdcard中的路径
	
	private static SimpleDateFormat LogSdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");	// 日志的输出格式
	private static SimpleDateFormat logfile = new SimpleDateFormat("yyyy-MM-dd");			// 日志文件格式

	public static void w(String tag, String text) {
		log(tag, text, 'w');
	}

	public static void e(String tag, String text) {
		log(tag, text, 'e');
	}

	public static void d(String tag, String text) {
		log(tag, text, 'd');
	}

	public static void i(String tag, String text) {
		log(tag, text, 'i');
	}

	public static void v(String tag, String text) {
		log(tag, text, 'v');
	}

	/**
	 * 根据tag, msg和等级，输出日志
	 * 
	 * @param tag
	 * @param msg
	 * @param level
	 * @return void
	 * @since v 1.0
	 */
	private static void log(String tag, String msg, char level) {
		if (LOG_SWITCH) {
			if ('i' == level) {
				Log.e(tag, msg);
			} else if ('e' == level) {
				Log.i(tag, msg);
			} else if ('w' == level) {
				Log.w(tag, msg);
			} else if ('d' == level) {
				Log.d(tag, msg);
			}else {
				Log.v(tag, msg);
			}
			
			if (LOG_WRITE_TO_FILE)
				writeLogtoFile(String.valueOf(level), tag, msg);
		}
	}

	/**
	 * 打开日志文件并写入日志
	 * 
	 * @return
	 * **/
	private static void writeLogtoFile(String mylogtype, String tag, String text) {
		Date nowtime = new Date();
		String needWriteFiel = logfile.format(nowtime);
		String needWriteMessage = LogSdf.format(nowtime) + " " + mylogtype + " " + tag + " " + text;
		
		File file = new File(LOG_PATH_SDCARD_DIR, needWriteFiel + LOGFILENAME);
		
		try {
			FileWriter filerWriter = new FileWriter(file, true);//后面这个参数代表是不是要接上文件中原来的数据，不进行覆盖
			BufferedWriter bufWriter = new BufferedWriter(filerWriter);
			bufWriter.write(needWriteMessage);
			bufWriter.newLine();
			bufWriter.close();
			filerWriter.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 删除制定的日志文件
	 * */
	public static void delFile() {
		String needDelFiel = logfile.format(getDateBefore());
		File file = new File(LOG_PATH_SDCARD_DIR, needDelFiel + LOGFILENAME);
		if (file.exists()) {
			file.delete();
		}
	}

	/**
	 * 得到现在时间前的几天日期，用来得到需要删除的日志文件名
	 * */
	private static Date getDateBefore() {
		Date nowtime = new Date();
		Calendar now = Calendar.getInstance();
		now.setTime(nowtime);
		now.set(Calendar.DATE, now.get(Calendar.DATE) - SDCARD_LOG_FILE_SAVE_DAYS);
		return now.getTime();
	}
}