Java追加写入文件

惨痛的教训，fos = new FileOutputStream(file,true);

默认为false，记得加上true

                    FileOutputStream fos = null;
                    OutputStreamWriter osw = null;
                    BufferedWriter bfw = null;
                    try{
                        fos = new FileOutputStream(file,true);
                        osw = new OutputStreamWriter(fos, StandardCharsets.UTF_8);
                        bfw = new BufferedWriter(osw);
                        bfw.write(loginSave);
                        bfw.write("\n");
                    }catch(Exception e){e.printStackTrace();}
                    finally {

                        if(bfw != null){
                            bfw.close();
                        }

                        if (osw != null) {
                            osw.close();
                        }
                        if(fos != null){
                            fos.close();
                        }
                    }