Android sd卡log日志

import android.os.Environment;
import android.util.Log;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class LOG {

    private static final int LEVEL_I = 1;

    private static final int LEVEL_D = 2;

    private static final int LEVEL_W = 3;

    private static final int LEVEL_E = 4;

    private static final String FILEPATH = "/folderPath";

    private static final String FILENAME = "log.txt";

    private static DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");

    public static void logD(String msg) {
        log(LEVEL_D, msg);
    }

    public static void logI(String msg) {
        log(LEVEL_I, msg);
    }

    public static void logW(String msg) {
        log(LEVEL_W, msg);
    }

    public static void logE(String msg) {
        log(LEVEL_E, msg);
    }

    public static void logE(Throwable ex) {
        if (!AppConstants.DEBUG) {
            return;
        }
        Writer writer = new StringWriter();
        PrintWriter printWriter = new PrintWriter(writer);
        ex.printStackTrace(printWriter);
        Throwable cause = ex.getCause();
        while (cause != null) {
            cause.printStackTrace(printWriter);
            cause = cause.getCause();
        }
        printWriter.close();
        String result = writer.toString();
        final Throwable t = AppConstants.DEBUG ? new Throwable() : null;
        final StackTraceElement[] elements = t != null ? t.getStackTrace() : null;
        String callerClassName = t != null ? elements[2].getClassName() : "N/A";
        int pos = callerClassName.lastIndexOf('.');
        if (pos >= 0) {
            callerClassName = callerClassName.substring(pos + 1);
        }
        final String tag = callerClassName;
        Log.e(tag, result);
        try {
            write(tag, result);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void log(int level, String msg) {
        if (!AppConstants.DEBUG) {
            return;
        }
        final Throwable t = AppConstants.DEBUG ? new Throwable() : null;
        final StackTraceElement[] elements = t != null ? t.getStackTrace() : null;
        String callerClassName = t != null ? elements[2].getClassName() : "N/A";
        String callerMethodName = t != null ? elements[2].getMethodName() : "N/A";
        int pos = callerClassName.lastIndexOf('.');
        if (pos >= 0) {
            callerClassName = callerClassName.substring(pos + 1);
        }
        final String tag = callerClassName;
        final StringBuffer buf = new StringBuffer();
        buf.append("[").append(callerMethodName).append("]  ").append(msg);

        switch (level) {
            case LEVEL_I:
                Log.i(tag, buf.toString());
                break;
            case LEVEL_D:
                Log.d(tag, buf.toString());
                break;
            case LEVEL_W:
                Log.w(tag, buf.toString());
                break;
            case LEVEL_E:
                Log.e(tag, buf.toString());
                break;
            default:
                break;
        }
        try {
            write(tag, buf.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void write(String tag, String log) throws IOException {
        String time = formatter.format(new Date(System.currentTimeMillis()));
        String logger = time + ">>>>>" + tag + ">>>>>" + ">>>>>" + log + "\n\n";
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            File dir = Environment.getExternalStorageDirectory();
            File file = new File(dir, FILEPATH);
            if (!file.exists()) {
                file.mkdirs();
            }
            FileOutputStream fos = new FileOutputStream(file + "/" + FILENAME, true);
            fos.write(logger.getBytes());
            fos.close();
        }
    }
}