Java边读文件变解析

ゝ一世哀愁。 2022-11-28 13:22 222阅读 0赞

## 我需要解决的问题 ##

> 每条数据用分隔符号隔开。使用时读取内容。没有换行。

## 数据格式 ##

> 123333333333;456546546546;

private List<String> getSNFromFile(String tmpFile, List<String> modellist, List<TerminalTaskStatus> errorSN) { 
    
            FileInputStream in = null;
            BufferedReader br = null;
            InputStreamReader isReader = null;
            List<String> dataList = new ArrayList<>();
    
            do { 
                try { 
                    in=new FileInputStream(tmpFile);
                    isReader =new InputStreamReader(in, "UTF-8");
                    br = new BufferedReader(isReader);
    
                    int page = 4096;
                    int off = 0;
                    char[] SNs = new char[page];
                    String buffer = "";     //保存读取但未处理的数据
                    String isDealing = "";  //保存正在处理的数据
                    int readbytes = 0;      //保存当前读取的字节数
                    while (true){ 
                        readbytes = br.read(SNs, off, page);
                        if (readbytes == -1 && buffer.isEmpty()){ 
                            //文件读取结束
                            break;
                        }else if (readbytes != -1){ 
                            off += readbytes;
                            String strByte = new String(SNs,0,readbytes);
                            buffer += strByte;
                            buffer.replace(" ","");
                        }
    
                        //文件中没有分割符号“；”,即只有一个数据
                        if (buffer.lastIndexOf(";") == -1){ 
                            TerminalTaskStatus errorTask = new TerminalTaskStatus();
                            //条件判断
                            if (buffer.length() != 11){ 
                                errorTask.setStatus(ConstantAPI.Data_is_illegal);
                                errorTask.setTerminalid(buffer);
                                errorSN.add(errorTask);
                                break;
                            }
                        }else{ 
                            if (readbytes >= page){ 
                                isDealing = buffer.substring(0, buffer.lastIndexOf(";"));
                            }else{ 
                                isDealing = buffer;
                            }
    
                            buffer = buffer.substring(buffer.lastIndexOf(";")+1);
                            //使用Apache库的StringUtils库解决数据前后的分隔符问题
                            String[] machines = StringUtils.splitByWholeSeparator(isDealing, ";");
    
                            //处理数据
                            if (machines != null && machines.length > 0){ 
                                for (String sn : machines){ 
                                    TerminalTaskStatus errorStatus = new TerminalTaskStatus();
                                    //数据必须是11位
                                    if (sn.length() != 11){ 
                                        errorStatus.setStatus(ConstantAPI.SN_is_illegal);
                                        errorStatus.setTerminalid(sn);
                                        errorSN.add(errorStatus);
                                        continue;
                                    }
    
                                    //保存一些数据
                                    String model = sn.substring(0, 3);
                                    if (!modellist.contains(model)){ 
                                        modellist.add(model);
                                    }
    
                                    //去重
                                    if (!dataList.contains(sn)){ 
                                        dataList.add(sn);
                                    }else{ 
                                        errorStatus.setStatus(ConstantAPI.Duplicate_SN);
                                        errorStatus.setTerminalid(sn);
                                        errorSN.add(errorStatus);
                                    }
                                }
                            }
                        }
    
                        if (readbytes < page){ 
                            break;
                        }
                    }
                }catch (FileNotFoundException e){ 
                    logger.error("FileNotFoundException, tmpFIle----"+tmpFile, e);
                    break;
                }catch (IOException e){ 
                    logger.error("IOException, tmpFIle----"+tmpFile, e);
                    break;
                }catch (Exception e){ 
                    logger.error("Exception, tmpFIle----"+tmpFile, e);
                    break;
                }finally { 
                    if (br != null) { 
                        try { 
                            br.close();
                        } catch (IOException e) { 
                            logger.error("IOException,close BufferedInputStream failed. tmpFIle----"+tmpFile, e);
                            break;
                        }
                    }
                    if (isReader != null){ 
                        try { 
                            isReader.close();
                        } catch (IOException e) { 
                            e.printStackTrace();
                        }
                    }
                    if (in != null) { 
                        try { 
                            in.close();
                        } catch (IOException e) { 
                            logger.error("IOException,close FileInputStream failed. tmpFIle----"+tmpFile, e);
                            break;
                        }
                    }
                }
            }while (false);
    
            return dataList;
        }

处理逻辑：  
将数据按指定大小读取出来，如果数据很多，做一个缓存，解析最大数据串，等于部分待下次解析。