J2ME 技術的學習與實踐者

[導入]字段輸入流FieldInuptStream

網站: JavaEye  作者: iwinyeah  鏈接：http://iwinyeah.javaeye.com/blog/174645  發表時間: 2008年03月21日

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/**
 * --------------------------------------------------
 * 字段輸入流
 * --------------------------------------------------
 * 從DataInputStream繼承
 * 主要增加了從文本格式輸入流中讀入數據字段的能力
 * --------------------------------------------------
 * 
 * @author iwinyeah 李永超
 * @version 1.0.0
 * */

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;

public class FieldInputStream extends DataInputStream {
	public final static int BIN_MODE = 0;

	public final static int TXT_MODE = 1;

	int mode;

	public FieldInputStream(InputStream in, int mode) {
		super(in);
		this.mode = mode;
	}

	public boolean getBoolean() throws IOException {
		if (mode == 0) {
			return readBoolean();
		} else {
			if ("1".equals(next())) {
				return true;
			}
			return false;
		}
	}

	public byte getByte() throws IOException {
		if (mode == 0) {
			return readByte();
		} else {
			return (byte) Integer.parseInt(next());
		}
	}

	public short getShort() throws IOException {
		if (mode == 0) {
			return readShort();
		} else {
			return (short) Integer.parseInt(next());
		}
	}

	public int getInt() throws IOException {
		if (mode == 0) {
			return readInt();
		} else {
			return Integer.parseInt(next());
		}
	}

	public long getLong() throws IOException {
		if (mode == 0) {
			return readLong();
		} else {
			return Long.parseLong(next());
		}
	}

	public String getString() throws IOException {
		if (mode == 0) {
			if (read() == 0) {
				return null;
			} else {
				return readUTF();
			}
		} else {
			return next();
		}
	}

	// 取下一標識符
	private byte[] buffer = new byte[255];

	private int length = 0;

	private boolean eos = false;

	private final static int INITIAL = 0;

	private final static int ESCAPE = 1;

	private final static int COMMENT_START = 2;

	private final static int LINE_COMMENT = 3;

	private final static String WHITESPACE = "\n\r\t";

	public String next() throws IOException {
		length = 0;
		int c = in.read();
		int status = INITIAL;
		READWHILE: while (c != -1) { // 一直讀到文件尾

			switch (status) {
			case INITIAL:
				if (c == '\n' || c == '\t') { // 如果是分隔符
					break READWHILE;
				} else if (c == '\\') {
					status = ESCAPE; // 設轉義字符標志
				} else if (c == '/') {
					status = COMMENT_START; // 設注釋標志
				} else {
					if (WHITESPACE.indexOf(c) < 0) {
						append(c);
					}
				}
				break;

			case ESCAPE: // 處理轉義字符
				switch (c) {
				case 'n':
					append('\n');
					break;

				case 'r':
					append('\r');
					break;

				case 't':
					append('\t');
					break;

				case 'b':
					append('\b');
					break;

				case 'f':
					append('\f');
					break;

				default:
					append(c);
					break;
				}
				status = INITIAL; // 設正常情況標志
				break;

			case COMMENT_START: // 處理注釋
				if (c == '/') {
					status = LINE_COMMENT; // 是行式注釋
				} else {
					status = INITIAL;
					// 如果都不是則把注釋起始符和剛讀入的字符都加入到標識符中
					append('/');
					append(c);
				}
				break;

			case LINE_COMMENT:
				if (c == '\n') {
					status = INITIAL; // 如果當前為行注釋狀態則要一直讀到行尾才恢復正常情況標志
					break READWHILE;
				}
				break;
			}
			c = in.read(); // 讀入下一字符
		}

		if (c == -1) {
			eos = true;
		}

		// 如果讀到文件尾時，標識符長度大于零，則返回標識符，否則返回NULL值
		if (length <= 0) {
			return null;
		} else {
			return new String(buffer, 0, length, "UTF-8");
		}
	}

	// 將讀入的字符加入緩沖區
	private void append(int c) {
		// 緩沖區不足時自動擴展
		if (length >= buffer.length) {
			byte[] xBuffer = new byte[buffer.length + 16];
			System.arraycopy(buffer, 0, xBuffer, 0, buffer.length);
			buffer = null;
			buffer = xBuffer;
		}

		buffer[length++] = (byte) c;
	}

	public boolean eos() {
		return eos;
	}
}

請參看我的另一篇文章：字段輸出流FieldOutputStreamhttp://iwinyeah.javaeye.com/admin/blogs/174644
本文的討論也很精彩，瀏覽討論>>


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文章來源:http://iwinyeah.javaeye.com/blog/174645

posted on 2008-03-21 22:19 iwinyeah 閱讀(169) 評論(0)  編輯  收藏 所屬分類: Java 基礎知識