将log信息写入sdcard

File mFile;
private void writeFile(String text) {
try {
if (bw != null) {
bw.newLine();// 换行
bw.write(text);
}
} catch (Exception e) {
e.printStackTrace();
}
}

BufferedWriter bw;
String SDPATH = Environment.getExternalStorageDirectory() + "/download/sensor_log.txt";
private void createFile() {
//String FILE_PATH = "/mnt/sdcard/download/sensorlog.txt";
mFile = new File(SDPATH);
Log.i("File", mFile.getAbsolutePath().toString());
try {
if (mFile.isFile()) {
mFile.deleteOnExit();
mFile = new File(mFile.getAbsolutePath());
}

java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(
"yyyy年mm月dd日 HH:mm:ss SSS");
String time2 = sdf.format(System.currentTimeMillis());
bw = new  BufferedWriter(new  FileWriter(SDPATH,true));
bw.newLine();
bw.write(" ======= 时间：" + time2 + "======");
bw.newLine();

} catch (Exception e) {
e.printStackTrace();
}
}

private void closeFile() {
try {
if (bw != null) {
bw.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}