recordengine.java

1个j2me实现的个人财务管理软件.程序的设计框架可以值得借鉴

package com.vp.echeckregister.utils;

import java.util.Vector;

import javax.microedition.rms.RecordComparator;
import javax.microedition.rms.RecordEnumeration;
import javax.microedition.rms.RecordFilter;
import javax.microedition.rms.RecordStore;
import javax.microedition.rms.RecordStoreException;
import javax.microedition.rms.RecordStoreFullException;

public final class RecordEngine {
	private static final int MIN_SIZE = 500;

	private RecordEngine() {

	}

	public static RecordStore createRecordStore(String tableName) {
		RecordStore rs = null;
		try {
			rs = RecordStore.openRecordStore(tableName, true);
		} catch (RecordStoreException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return rs;
	}

	public static synchronized int addRecord(String tableName, byte[] data) {
		int recordId = -1;
		RecordStore rs = null;

		try {
			rs = RecordStore.openRecordStore(tableName, true);

			int availableSize = rs.getSizeAvailable();
			if (availableSize - data.length > MIN_SIZE) {
				recordId = rs.addRecord(data, 0, data.length);
			} else {
				throw new RecordStoreFullException(
						"RecordStore available size is smaller than MIN_SIZE");
			}
		} catch (RecordStoreException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			closeRecordStore(rs);
		}

		return recordId;
	}

	public static synchronized void setRecord(String tableName, byte[] data, int recordId) {
		RecordStore rs = null;
		try {
			rs = RecordStore.openRecordStore(tableName, true);
			byte[] temp = rs.getRecord(recordId);
			int availableSize = rs.getSizeAvailable();
			if (availableSize - (data.length - temp.length) > MIN_SIZE) {
				rs.setRecord(recordId, data, 0, data.length);
			} else {
				throw new RecordStoreFullException(
						"RecordStore available size is smaller than MIN_SIZE");
			}
		} catch (RecordStoreException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			closeRecordStore(rs);
		}
	}

	public static synchronized byte[] getRecord(String tableName, int recordId) {
		byte[] data = null;
		RecordStore rs = null;
		try {
			rs = RecordStore.openRecordStore(tableName, true);
			data = rs.getRecord(recordId);
		} catch (RecordStoreException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			closeRecordStore(rs);
		}
		return data;
	}

	public static synchronized boolean deleteRecord(String tableName, int recordId) {
		boolean boo = false;
		RecordStore rs = null;
		try {
			rs = RecordStore.openRecordStore(tableName, true);
			rs.deleteRecord(recordId);
			boo = true;
		} catch (RecordStoreException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			closeRecordStore(rs);
		}
		return boo;
	}

	public static synchronized int[] getRecordIds(String tableName, RecordFilter filter,
			RecordComparator comparator) {
		RecordStore rs = null;
		RecordEnumeration re = null;
		int[] ids = null;
		try {
			rs = RecordStore.openRecordStore(tableName, true);
			re = rs.enumerateRecords(filter, comparator, false);
			int i = 0;
			while (re.hasNextElement()) {
				ids[i] = re.nextRecordId();
				i++;
			}
		} catch (RecordStoreException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			closeRecordStore(rs);
		}
		return ids;
	}

	public static synchronized Vector getRecords(String tableName, RecordFilter filter,
			RecordComparator comparator) {
		Vector recordVec = new Vector();
		int[] recordIds = getRecordIds(tableName, filter, comparator);
		if (null != recordIds) {
			for (int i = 0; i < recordIds.length; i++) {
				recordVec.addElement(getRecord(tableName, recordIds[i]));
			}
		}

		return recordVec;
	}

	private static void closeRecordStore(RecordStore rs) {
		if (null != rs) {
			try {
				rs.closeRecordStore();
			} catch (RecordStoreException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				rs = null;
			}
		}
	}
}