simplerecord.java

j2me开发的一些例子

/*
 * Copyright (c) 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
 */

package examples.addressbook;
import java.lang.*;
import java.io.*;
import java.util.*;
import javax.microedition.rms.*;

/**
 * This class provides static methods that allow us
 * to hide the format of a record.
 * N.B. no synchronized access is provided
 */
public final class SimpleRecord {

    private final static int FIRST_NAME_INDEX = 0;
    private final static int LAST_NAME_INDEX = 20;
	private final static int FIELD_LEN = 20;
    private final static int PHONE_INDEX = 40;
    private final static int MAX_REC_LEN = 60;

    private static StringBuffer recBuf =
        new StringBuffer(MAX_REC_LEN);

    // Don't let anyone instantiate this class
    private SimpleRecord() {}

    // Clear internal buffer
    private static void clearBuf() {
        for (int i = 0; i < MAX_REC_LEN; i++) {
            recBuf.insert(i, ' ');
        }
        recBuf.setLength(MAX_REC_LEN);
    }

    /**
     * Takes component parts and return a record suitable
     * for our address book.
     *
     *  return  byte[] the newly created record
     *  first   record field: first name
     *  last    record field: last name
     *  num     record field: phone number
     */
    public static byte[] createRecord(String first,
                                      String last,
                                      String num) {
        clearBuf();
        recBuf.insert(FIRST_NAME_INDEX, first);
        recBuf.insert(LAST_NAME_INDEX, last);
        recBuf.insert(PHONE_INDEX, num);
        recBuf.setLength(MAX_REC_LEN);
        return recBuf.toString().getBytes();
    }

    /**
     * Extracts the first name field from a record.
     *  return  String contains the first name field
     *  b       the record to parse
     */
    public static String getFirstName(byte[] b) {
        return new String(b, FIRST_NAME_INDEX, FIELD_LEN).trim();
    }

    /**
     * Extracts the last name field from a record.
     *  return  String contains the last name field
     *  b       the record to parse
     */
    public static String getLastName(byte[] b) {
        return new String(b, LAST_NAME_INDEX, FIELD_LEN).trim();
    }

    /**
     * Extracts the phone number field from a record.
     *  return  String contains the phone number field
     *  b       the record to parse
     */
    public static String getPhoneNum(byte[] b) {
        return new String(b, PHONE_INDEX, FIELD_LEN).trim();
    }
}