dbapi.java

英语背单词联网版本

/*
 * dbapi.java
 *
 * Created on 2003年7月3日, 下午10:56
 */

package handenglish;

/**
 * dbapi.java
 *
 * Created on 2002年10月8日, 下午10:37
 */

import javax.microedition.midlet.*;
import javax.microedition.rms.*;
import java.io.*;
import java.util.*;
import javax.microedition.lcdui.*;

/**
 *
 * @author  Administrator
 * @version
 */



/*class DriverStruct
{
  public    String certificate;
  public    Image picture;
  public    String  name;
  public    Date birthday;
  public    short classes;
  public    short point;
  public    String  punish;
  public    short sex;
  public    Date makedate;
  public    Date enddate;
  public    String  address;
}*/


public class DbApi {
    public RecordStore myRecordStore;
    public boolean dbOpenJug;
    
    
    public DbApi(String dbName) {
        dbOpenJug=false;
        openDatabase(dbName);
    }
    public boolean openDatabase(String dbName) {
        if (dbOpenJug) {
            try {
                myRecordStore.closeRecordStore();
            }
            catch(RecordStoreException e) {
                return false;
            }
        }
        try {
            myRecordStore= RecordStore.openRecordStore(dbName,true);
            dbOpenJug=true;
        }
        catch(RecordStoreException e) {
            return false;
        }
        return true;
    }
    
    public byte[] readRecord(int nowRecordId) {
        try {
            if (myRecordStore.getNumRecords()>=nowRecordId) {
                RecordEnumeration tempEnumRecord;
                tempEnumRecord=getAllRecord();
                for(int i=1;i<nowRecordId;i++)
                    tempEnumRecord.nextRecord();
                return tempEnumRecord.nextRecord();
            }
            else
                return null;
        }
        catch(Exception e) {
            return null;
        }
    }
    
    
    public int addDatabase(byte[] dbInfo) {
        
        if ((dbInfo.length>0)&&(dbOpenJug)) {
            try {
                return myRecordStore.addRecord(dbInfo,0,dbInfo.length);
            }
            catch(RecordStoreException e) {
                return -1;
            }
        }
        return -1;
    }
    public boolean closeDatabase() {
        
        if (dbOpenJug) {
            try {
                myRecordStore.closeRecordStore();
                dbOpenJug = false;
                return true;
            }
            catch(RecordStoreException e) {
            }
        }
        return false;
    }
    
    public int getRecordNum() {
        int num;
        if(dbOpenJug) {
            try {
                num=myRecordStore.getNumRecords();
                return num;
            }
            catch(Exception e) {
                return 0;
            }
        }
        else
            return 0;
    }
    public RecordEnumeration getAllRecord() {
        try {
            return myRecordStore.enumerateRecords(null,null,false);
        }
        catch(Exception e) {
            return null;
        }
    }
    public void recordIndex(Hashtable indexHash) {
        byte[] tempB;
        byte[] tempRecord = new byte[100];
        int tLen,tId;
        RecordEnumeration tempEnumRecord;
        ByteArrayInputStream myByteStream=new ByteArrayInputStream(tempRecord);
        DataInputStream myIn=new DataInputStream(myByteStream);
        tempEnumRecord=getAllRecord();
        try {
            while(tempEnumRecord.hasNextElement()) {
                tId = tempEnumRecord.nextRecordId();
                tLen = myRecordStore.getRecordSize( tId );
                if ( tLen > tempRecord.length )
                    tempRecord = new byte[tLen+40];
                //tempRecord=tempEnumRecord.nextRecord();
                myRecordStore.getRecord( tId,tempRecord,0 );
                myByteStream.reset();
                int tempI=myIn.readInt();
                String tempS=myIn.readUTF();
                indexHash.put(tempS,new Integer(tempI));
            }
        }
        catch (Exception e) {
        }
    }
    
    public boolean deleteDatabase(String dbName) {
        if (dbOpenJug) {
            closeDatabase();
        }
        try {
            RecordStore.deleteRecordStore(dbName);
            return true;
        }
        catch (Exception e) {
            return false;
        }
    }
    
    public boolean deleteRecord(int recordId) {
        try {
            myRecordStore.deleteRecord(recordId);
            return true;
        }
        catch(Exception e ) {
            return false;
        }
    }
    
    public void  deleteAll(){
        if ( !dbOpenJug ) return;
        try {
            int tempId;
            RecordEnumeration tempEnumRecord =getAllRecord();
            while(tempEnumRecord.hasNextElement()) {
                tempId=tempEnumRecord.nextRecordId();
                deleteRecord( tempId );
            }
        }
        catch (Exception e) {}
    }
/*    public void setID(int recordID){
        byte[] t = {0};
        try {
            if ( getRecordNum() < 1 )
                myRecordStore.setRecord( 1,t,0,t.length);
        }catch (Exception e) {}
    } */
}