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靈活使用insert ignore奇淫巧技查看全部
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從這節課開始看,
本節概括了一些框架特性
Spring IOC整合Service
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public?class?ResortByDel?{ ????private?static?String?BIG_FILE_NAME?=?"D:\\test1.txt"; ????private?static?Integer?BATCH_SIZE?=?100; ????private?static?String?LINE_SEPARATOR?=?","; ????private?static?String?SORT_FILE_NAME?=?"D:\\test2.txt"; ????private?static?List<String>?separateFile()?{ ????????List<String>?fileNameList?=?new?ArrayList<>(); ????????try?(BufferedReader?reader?=?new?BufferedReader(new?FileReader(BIG_FILE_NAME)))?{ ????????????int?index?=?0; ????????????List<String>?batchLineList?=?new?ArrayList<>(BATCH_SIZE); ????????????String?line; ????????????while?((line?=?reader.readLine())?!=?null?||?batchLineList.size()?>?0)?{ ????????????????if?(line?!=?null)?batchLineList.add(line); ????????????????if?(batchLineList.size()?==?BATCH_SIZE?||?(line?==?null?&&?batchLineList.size()?>?0))?{ ????????????????????//?內容排序 ????????????????????batchLineList.sort((a,?b)?->?a.compareTo(b)); ????????????????????//?寫小文件 ????????????????????String?fileName?=?BIG_FILE_NAME?+?".tmp."?+?index++; ????????????????????try?(FileWriter?tmpWriter?=?new?FileWriter(fileName))?{ ????????????????????????for?(String?val?:?batchLineList)?{ ????????????????????????????tmpWriter.write(val?+?"\r\n"); ????????????????????????} ????????????????????} ????????????????????fileNameList.add(fileName); ????????????????????batchLineList.clear(); ????????????????} ????????????} ????????}?catch?(IOException?e)?{ ????????????e.printStackTrace(); ????????} ????????return?fileNameList; ????} ????private?static?void?mergeFile(List<String>?fileNameList)?{ ????????Map<BufferedReader,?String>?map?=?new?HashMap<>(); ????????String?preStr?=?null; ????????try?(FileWriter?writer?=?new?FileWriter(SORT_FILE_NAME))?{ ????????????for?(String?fileName?:?fileNameList)?{ ????????????????BufferedReader?tmpReader?=?new?BufferedReader(new?FileReader(fileName)); ????????????????map.put(tmpReader,?tmpReader.readLine()); ????????????} ????????????while?(true)?{ ????????????????boolean?canRead?=?false; ????????????????Map.Entry<BufferedReader,?String>?minEntry?=?null; ????????????????for?(Map.Entry<BufferedReader,?String>?entry?:?map.entrySet())?{ ????????????????????String?value?=?entry.getValue(); ????????????????????if?(value?==?null)?{ ????????????????????????continue; ????????????????????} ????????????????????//?獲取當前?reader?內容最小?entry ????????????????????if?((minEntry?==?null)?||?(Integer.valueOf(value)?<?Integer.valueOf(minEntry.getValue())))?{ ????????????????????????minEntry?=?entry; ????????????????????} ????????????????????canRead?=?true; ????????????????} ????????????????//?當且僅當所有?reader?內容為空時,跳出循環 ????????????????if?(!canRead)?{ ????????????????????break; ????????????????} ????????????????//去重 ????????????????if?(preStr?!=?null?&&?preStr.equals(minEntry.getValue()))?{ ????????????????????minEntry.setValue(minEntry.getKey().readLine()); ????????????????????continue; ????????????????} ????????????????preStr?=?minEntry.getValue(); ????????????????writer.write(minEntry.getValue()?+?"\r\n"); ????????????????minEntry.setValue(minEntry.getKey().readLine()); ????????????} ????????}?catch?(Exception?e)?{ ????????????e.printStackTrace(); ????????}?finally?{ ????????????//?注意關閉分片文件輸入流 ????????????for?(BufferedReader?reader?:?map.keySet())?{ ????????????????try?{ ????????????????????reader.close(); ????????????????}?catch?(IOException?e)?{ ????????????????????e.printStackTrace(); ????????????????} ????????????} ????????} ????} ????public?static?void?main(String[]?args)?throws?IOException?{ ????????List<String>?separateFiles?=?separateFile(); ????????mergeFile(separateFiles); ????} }
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mybatis做對象關系映射查看全部
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數據庫連接池配置
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mybatis 連表查詢
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