為了以後便於查詢

/**列印資訊類*/
public class FileWrite {

    /**根目錄*/
    private  static final String SDCARD_PATH = Environment.getExternalStorageDirectory().getPath();         
    private  static final String LOG_FILE_PATH = SDCARD_PATH + File.separator+"lou"+File.separator+"log.log";   
    private  static final
 
 String parentpath = SDCARD_PATH + File.separator+"lou";   
    private static final String mCharset = "utf-8";
    private static FileWrite fw = null;
    private static FileOutputStream mFos;
    private static File mLogFile;
    private static File parentFile;
    private FileWrite(){
        //判斷檔案是否存在
 

        createIfNotExist(LOG_FILE_PATH);
        try {
            //此處判斷檔案是否存在，若存在則會追加 否則建立檔案
            mFos = new FileOutputStream(mLogFile, true);
//          mFos = new FileOutputStream(LOG_FILE_PATH, true);
        } catch (FileNotFoundException e) {
            Log.e("lou", "FileWrite FileNotFoundException"
 
);
            e.printStackTrace();
        }
    }
    /**建立檔案 判斷檔案是否存在
     * @param path 檔案路徑*/
    private void createIfNotExist(String path) {
        parentFile = new File(parentpath);
        if(!parentFile.exists()){
            parentFile.mkdir();
        }
        mLogFile = new File(path);
        if(!mLogFile.exists()){
            try {
                mLogFile.createNewFile();
            } catch (IOException e) {
                Log.e("lou", "FileWrite.createIfNotExist createNewFile failed");
                e.printStackTrace();
            }
        }
    }
    public static FileWrite getInstance(){
        if(fw == null){
            fw = new FileWrite();
        }
        return fw;
    }

    /**
     * 此處是呼叫的介面
     * @param content 列印的內容*/
    public void WriteString(String content){
        Date date = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        content = sdf.format(date)+":"+content;
        byte[] data;
        try {
            data = content.getBytes(mCharset);
            writeByte(data);
        } catch (UnsupportedEncodingException e) {
            Log.e("lou", ""+e.getMessage());
            e.printStackTrace();
        }
    }

    /**寫檔案
     * @param data 資料*/
    private boolean writeByte(byte[] data) {
        try {
            mFos.write(data);
            mFos.write("\r\n".getBytes());
            mFos.flush();
            return true;
        } catch (IOException e) {
            Log.e("lou", "writeByte failed");
            e.printStackTrace();
        }
        return false;
    }
}