android按行读取文件内容的几个方法

                        mWeightLogFile.createNewFile();
                    }
                    if (!mWeightLogFile.exists()) {
                        Log.i(TAG, "out = null");
                        throw new Exception("creation of file '"+mWeightLogFile.toString()+"' failed");
                    }
                    if (!mWeightLogFile.canWrite()) 
                        throw new Exception("file '"+mWeightLogFile.toString()+"' is not writable");
                    out = new FileWriter(mWeightLogFile, true);
                    if (!fileExists) {
                        String header = createHeadLine();
                        out.write(header);
                        out.write('n');
                    }
                }
                Log.i(TAG, "out != null");
                String extras = createBatteryInfoLine(batteryChangeIntent);
                out.write(extras);
                out.write('n');
                out.flush();