Java按照时间顺序从hbase中读出数据

- 日理万妓 2023-10-11 11:36 36阅读 0赞

1,从hbase中读出数据并存储在ArrayList<Map<String,String>>中，

@Override
        public ArrayList<Map<String, Object>> getAllHistoryOrderByTime(String namespace, String tableName) {
            TableName tablename=TableName.valueOf(FillDataTableName(namespace,tableName));
            Table table = null;
            ArrayList<Map<String,Object>> arrayList = new ArrayList<>();
            try {
                conn = ConnectionFactory.createConnection(conf);
                //管理类
                table = conn.getTable(tablename);
                ResultScanner results = table.getScanner(new Scan());
                for (Result result : results){
                    Map<String,Object> map = new HashMap<>();
                    for(Cell cell : result.rawCells()){
                        String row = Bytes.toString(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength());
                        //String family =  Bytes.toString(cell.getFamilyArray(),cell.getFamilyOffset(),cell.getFamilyLength());
                        String colName = Bytes.toString(cell.getQualifierArray(),cell.getQualifierOffset(),cell.getQualifierLength());
                        String value = Bytes.toString(cell.getValueArray(), cell.getValueOffset(), cell.getValueLength());
                        map.put("modelName",row);
                        if(colName.equals("tableName")){
                            map.put("tableName",value);
                        }if(colName.equals("project")){
                            map.put("project",value);
                        }if(colName.equals("columns")){
                            ArrayList<String> columnsList = StringOptions.String2ArrayList(value);
                            map.put("columns",columnsList);
                        }if(colName.equals("preProcess")){
                            ArrayList<String> preProcessList = StringOptions.String2ArrayList(value);
                            map.put("preProcess",preProcessList);
                        }if(colName.equals("result")){
                            map.put("result",value);
                        }if(colName.equals("params")){
                            Map<String,String> paramsMap = StringOptions.String2Map(value);
                            map.put("params",paramsMap);
                        }
                        //获取时间戳
                        long lTmstmp = cell.getTimestamp();
                        Date date = new Date(lTmstmp);
                        map.put("Date",date.toString());
                    }
                    arrayList.add(map);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            return SortOptions.sortByTime(arrayList);
        }

其中ArrayList<Map<String,String>>初始化为：

ArrayList<Map<String,String>> arrayList = new ArrayList<>();
    arrayList.add(new HashMap<String, String>() {
       {
        put("Name","1");
        put("Date","Sat Sep 21 16:06:55 CST 2019");
    }
    });

2、将ArrayList<Map<String,String>>按照时间戳进行排序

public static ArrayList<Map<String,String>> sortByTime(ArrayList<Map<String,String>> inputArrayList){
        Comparator c = new Comparator<Map<String,String>>() {
            @Override
            public int compare(Map<String,String> o1, Map<String,String> o2) {
                // TODO Auto-generated method stub
                if(string2Date(o1.get("Date")).before(string2Date(o2.get("Date"))))
                    return 1;
                    //注意！！返回值必须是一对相反数，否则无效。jdk1.7以后就是这样。
                    //    else return 0; //无效
                else return -1;
            }
        };
        Collections.sort(inputArrayList,c);
        return inputArrayList;
    }

3、将字符串转换为Date类型

public static Date string2Date(String strDate) {
        Date date = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy", java.util.Locale.US);
        try {
             date = sdf.parse(strDate.toString());
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return date;
        }