Lap Trinh Java05-RMS

8/3/2019 Lap Trinh Java05-RMS

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Record Management System

(RMS)ThS. Trn Minh Trit

i hc Khoa hc T nhin HQG-HCMKhoa Cng Ngh Thng Tin


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Ni dung

Lu tr d liu ti server t xaLu tr cc b vi Record Management System

Phm vi qun l ca Record Management

Qun l Record Store

nh ngha, nh dng, thm vo Record StoresTruy cp v xa trong Record Store

Truy vn trn Record Store


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Lu tr t xa

C th s dng lu tr t xa (remote storage) trn serveru:

Kch thc ng dng nh

Ch lu nhng d liu cn thit

Ni dung ngThng dng trong lp trnh game

Khuyt:

Khng ng tin cy

Tn thi gian v chi ph

Chi ph server


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Record Store?

Trong MIDP, vic lu tr s dng record storeMt record store l 1 tp hp cc record

Vic t chc lu tr tht s do ci t ca MIDP

Record store c th cha trn l hard disk, battery-

backed RAM, flash ROMMi record l 1 mng cc byte v c s nh danh duynht

Ni dung ca mng byte do ng dng t quy nh

Cn dng gijavax.microedition.rms


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RMS

MIDP lu tr thng tin bng cch dng h thng lu tr(Record Management System - RMS).

RMS cho php c, ghi d liu, sp xp, tm kim v lythng tin theo nhiu ty chn khc nhau


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Record Store trong MIDP


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D liu trong Record Store

Cc record trong 1record store ct chc l mngcc byte

Cc mng byte

khng cn cng di

Mi record c 1nh danh (ID)ring

Record c th khng lin tip v 1 s record b xa

Record l mng byte c nh dng theo nh ring


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Qun l Record trong MIDP

Mi Record store u c tn v c phn bit thng quatn

Tn gm ti a 32 k t (case sensitive)

Hai record store trong cng 1 MIDlet suite khng c

trng tn


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Qun l RecordStore

S dng phng thc static m 1 record store:publicstaticRecordStoreopenRecordStore(

String recordStoreName,

boolean createIfNecessary)

throwsRecordStoreException,RecordStoreFullException,RecordStoreNotFoundException

ng recordstore bng phng thc:

closeRecordStore()Xa record store bng phng thc staticdeleteRecordStore()

Ly danh sch Recordstore bng phng thc static

listRecordStores()


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To record store

RecordStoreopenRecordStore(String recordStoreName,

boolean createIfNecessary)

RecordStoreopenRecordStore(String recordStoreName,

boolean createIfNecessary,

int authmode, boolean writable)

RecordStoreopenRecordStore(

String recordStoreName,

String vendorName, String suiteName)


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To record store

createIfNecessary yu cu to record store nu chac)

authmode:

AUTHMODE_PRIVATE

AUTHMODE_ANYwritable - true nu RecordStore cho php cc MIDletsuite khc c th ghi (nu cp quyn)

vendorName tn NSX ca MIDlet suite

suiteName - tnMIDlet suite


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RecordStore API

voidcloseRecordStore()voiddeleteRecordStore(String recordStoreName)

String[] listRecordStores()

intaddRecord(byte[] data, int offset, int numBytes)

voidsetRecord (int recordId, byte[] newData,int offset, int numBytes)

voiddeleteRecord (int recordId)


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Truy cp 1 record store

byte[] getRecord (int recordId)intgetRecord (int recordId, byte[] buffer, int offset)

intgetRecordSize (int recordId)

intgetNextRecordID()

intgetNumRecords()longgetLastModified()


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Thao tc c v ghi

Cp pht streamGhi d liu

Flush d liu trong stream

Chuyn stream d liu thnh mng

Ghi mng vo record storeng cc stream


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Thao tc c v ghi (#1)

publicvoidwriteStream(boolean[] bData, int[] iData, String[] sData) {

// Write data into an internal byte array

ByteArrayOutputStream strmBytes =

newByteArrayOutputStream();// Write Java data types into the above byte array

DataOutputStream strmDataType =

newDataOutputStream(strmBytes);


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Thao tc c v ghi (#2)byte[] record;

for (int i = 0; i < sData.length; i++) {

// Write Java data types

strmDataType.writeBoolean(bData[i]);

strmDataType.writeInt(iData[i]);

strmDataType.writeUTF(sData[i]);// Clear any buffered datastrmDataType.flush();// Get stream data into byte array and write record

record = strmBytes.toByteArray();rs.addRecord(record, 0, record.length);// Toss any data in the internal array so writes// starts at beginning (of the internal array)

strmBytes.reset();


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Thao tc c v ghi (#3)

strmBytes.close();strmDataType.close();

}


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nh dng v thm RecordTrc khi thm record, cn nh dng record


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Ly Record

Ly recordpublicbyte[] getRecord(int recordId)

throwsRecordStoreException,

RecordStoreNotOpenException,

InvalidRecordIDException


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Xa Record

Khi xa Record, cn truyn record ID# vo hmdeleteRecord() ca i tng RecordStore.

record ID# b xa s khng c dng li


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Xa Record


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Truy vn Record

Interface RecordFilter cho php lc cc record theo cctiu ch khc nhau. Phng thc matches() c dng nh ngha iu kin lc

C th dng RecordEnumeration duyt tun t quacc record kim tra record no tha iu kin lc.

Interface RecordComparator cung cp phng thccompare() cho php nh ngha cch so snh 2 record khisp xp


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Lc Record

Interface RecordFilter cho php lc cc record theo cc

tiu ch khc nhau. Phng thc matches() c dng nh ngha iu kin lc


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RecordFilter APIclassSearchFilterimplementsRecordFilter {

privateString searchText = null;

publicSearchFilter(String searchText) {// Text to findthis.searchText = searchText.toLowerCase();}

publicbooleanmatches(byte[] candidate) {String str = newString(candidate).toLowerCase();// Does the text exist?if (searchText != null&&str.indexOf(searchText)!=-1) { returntrue;

} else { returnfalse;}

}

}


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RecordFilter API

// Create search filterSearchFilter search = new SearchFilter("abc");

// Reference filter when creating the result set

RecordEnumeration re = rs.enumerateRecords (search, null, false);

// If there is at least one record in result set,

// a match was found

if (re.numRecords() > 0) {

// At least one record in the result set... ...

}


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Sp xp Record sp xp cn dng interface RecordComparator.

Cn ci t phng thc compare() so snh 2 record


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RecordComparator API

intcompare(byte[] rec1, byte[] rec2)staticintEQUIVALENT

staticintFOLLOWS

staticintPRECEDES


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publicclasscomparatorimplementsRecordComparator {publicintcompare(byte[] rec1, byte[] rec2) {

String str1 = newString(rec1),str2 = newString(rec2);

int result = str1.compareTo(str2);if (result == 0) {return RecordComparator.EQUIVALENT;} elseif (result < 0) {returnRecordComparator.PRECEDES;

} else {returnRecordComparator.FOLLOWS;

}}

}


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// Create a new comparator for sortingComparator comp = newComparator();

// Reference the comparator when creating the result

setRecordEnumeration re = rs.enumerateRecords

(null, comp, false);

// Retrieve each record in sorted orderwhile (re.hasNextElement()) {

String str = newString(re.nextRecord()); ...

}


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Duyt Record

C th duyt qua cc record bng interfaceRecordEnumeration

Xc nh recordno c chn

Th t sp xp

Tr v cc recordc chn theoth t quy nh

Tr v tt c record(khng sp th t)


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RecordEnumeration API

intnumRecords()byte[] nextRecord()

intnextRecordId()

byte[] previousRecord()

intpreviousRecordId()booleanhasNextElement()


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RecordEnumeration API

booleanhasPreviousElement()voidkeepUpdated(boolean keepUpdated)

booleanisKeptUpdated()

voidrebuild()

voidreset()voiddestroy()


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Pht hin s thay i ca Record

C th ng k eventlistener cho 1 RecordStoreS dng phng thc addRecordListener() vremoveRecordListener()

RecordListener c 3 hm callback:

publicvoidrecordAdded(RecordStore rs, int id)publicvoidrecordChanged(RecordStore rs, int id)

publicvoidrecordDeleted(RecordStore rs, int id)


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RecordListener API

RecordListener cho php nhn x l s kin khi c sthay i, thm, xa trong record store.

Cc bc s dng RecordListener:

M (hay to)record store.To 1 listener mi

Ci t cc phng thc ca interface RecordListener


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RecordListener API

voidrecordAdded( RecordStore recordStore,int recordId)

voidrecordChanged( RecordStore recordStore,

int recordId)

voidrecordDeleted( RecordStore recordStore,int recordId)


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To 1 record store// Open record storers = RecordStore.openRecordStore(REC_STORE, true);

...// Using handle to open record store, create a listenerrs.addRecordListener(newDemoRecordListener());...classDemoRecordListenerimplementsRecordListener {

publicvoidrecordAdded(RecordStore recordStore,int recordId)

{ System.out.println("Record added"); }publicvoidrecordDeleted(RecordStore recordStore,

int recordId){ System.out.println("Record deleted"); }publicvoid recordChanged(RecordStore recordStore,

int recordId){ System.out.println("Record changed"); }

}


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S dng file Resource

C th s dng lu tr trong MIDP: c cc file resourcetrong file JAR ca MIDlet suite

Dng phng thc getResourceAsStream().

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Lap Trinh Java05-RMS