实现txt文件的翻页

【实例简介】

本例子实现了对TXT文件的读取，主要展现翻页效果的制作

【实例截图】

【核心代码】

public BookPageFactory(int w, int h) {
		// TODO Auto-generated constructor stub
		mWidth = w;
		mHeight = h;
		mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
		mPaint.setTextAlign(Align.LEFT);
		mPaint.setTextSize(m_fontSize);
		mPaint.setColor(m_textColor);
		mVisibleWidth = mWidth - marginWidth * 2;
		mVisibleHeight = mHeight - marginHeight * 2;
		mLineCount = (int) (mVisibleHeight / m_fontSize); //可显示的行数
	}

	public void openbook(String strFilePath) throws IOException {
		book_file = new File(strFilePath);
		long lLen = book_file.length();
		m_mbBufLen = (int) lLen;
		m_mbBuf = new RandomAccessFile(book_file, "r").getChannel().map(
				FileChannel.MapMode.READ_ONLY, 0, lLen);
	}
	

	protected byte[] readParagraphBack(int nFromPos) {
		int nEnd = nFromPos;
		int i;
		byte b0, b1;
		if (m_strCharsetName.equals("UTF-16LE")) {
			i = nEnd - 2;
			while (i > 0) {
				b0 = m_mbBuf.get(i);
				b1 = m_mbBuf.get(i   1);
				if (b0 == 0x0a && b1 == 0x00 && i != nEnd - 2) {
					i  = 2;
					break;
				}
				i--;
			}

		} else if (m_strCharsetName.equals("UTF-16BE")) {
			i = nEnd - 2;
			while (i > 0) {
				b0 = m_mbBuf.get(i);
				b1 = m_mbBuf.get(i   1);
				if (b0 == 0x00 && b1 == 0x0a && i != nEnd - 2) {
					i  = 2;
					break;
				}
				i--;
			}
		} else {
			i = nEnd - 1;
			while (i > 0) {
				b0 = m_mbBuf.get(i);
				if (b0 == 0x0a && i != nEnd - 1) {
					i  ;
					break;
				}
				i--;
			}
		}
		if (i < 0)
			i = 0;
		int nParaSize = nEnd - i;
		int j;
		byte[] buf = new byte[nParaSize];
		for (j = 0; j < nParaSize; j  ) {
			buf[j] = m_mbBuf.get(i   j);
		}
		return buf;
	}

	//读取上一段落
	protected byte[] readParagraphForward(int nFromPos) {
		int nStart = nFromPos;
		int i = nStart;
		byte b0, b1;
		//根据编码格式判断换行
		if (m_strCharsetName.equals("UTF-16LE")) {
			while (i < m_mbBufLen - 1) {
				b0 = m_mbBuf.get(i  );
				b1 = m_mbBuf.get(i  );
				if (b0 == 0x0a && b1 == 0x00) {
					break;
				}
			}
		} else if (m_strCharsetName.equals("UTF-16BE")) {
			while (i < m_mbBufLen - 1) {
				b0 = m_mbBuf.get(i  );
				b1 = m_mbBuf.get(i  );
				if (b0 == 0x00 && b1 == 0x0a) {
					break;
				}
			}
		} else {
			while (i < m_mbBufLen) {
				b0 = m_mbBuf.get(i  );
				if (b0 == 0x0a) {
					break;
				}
			}
		}
		int nParaSize = i - nStart;
		byte[] buf = new byte[nParaSize];
		for (i = 0; i < nParaSize; i  ) {
			buf[i] = m_mbBuf.get(nFromPos   i);
		}
		return buf;
	}

	protected Vector<String> pageDown() {
		String strParagraph = "";
		Vector<String> lines = new Vector<String>();
		while (lines.size() < mLineCount && m_mbBufEnd < m_mbBufLen) {
			byte[] paraBuf = readParagraphForward(m_mbBufEnd); //读取一个段落
			m_mbBufEnd  = paraBuf.length;
			try {
				strParagraph = new String(paraBuf, m_strCharsetName);
			} catch (UnsupportedEncodingException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			String strReturn = "";
			if (strParagraph.indexOf("\r\n") != -1) {
				strReturn = "\r\n";
				strParagraph = strParagraph.replaceAll("\r\n", "");
			} else if (strParagraph.indexOf("\n") != -1) {
				strReturn = "\n";
				strParagraph = strParagraph.replaceAll("\n", "");
			}

			if (strParagraph.length() == 0) {
				lines.add(strParagraph);
			}
			while (strParagraph.length() > 0) {
				int nSize = mPaint.breakText(strParagraph, true, mVisibleWidth,
						null);
				lines.add(strParagraph.substring(0, nSize));
				strParagraph = strParagraph.substring(nSize);
				if (lines.size() >= mLineCount) {
					break;
				}
			}
			if (strParagraph.length() != 0) {
				try {
					m_mbBufEnd -= (strParagraph   strReturn)
							.getBytes(m_strCharsetName).length;
				} catch (UnsupportedEncodingException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
		return lines;
	}

	protected void pageUp() {
		if (m_mbBufBegin < 0)
			m_mbBufBegin = 0;
		Vector<String> lines = new Vector<String>();
		String strParagraph = "";
		while (lines.size() < mLineCount && m_mbBufBegin > 0) {
			Vector<String> paraLines = new Vector<String>();
			byte[] paraBuf = readParagraphBack(m_mbBufBegin);
			m_mbBufBegin -= paraBuf.length;
			try {
				strParagraph = new String(paraBuf, m_strCharsetName);
			} catch (UnsupportedEncodingException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			strParagraph = strParagraph.replaceAll("\r\n", "");
			strParagraph = strParagraph.replaceAll("\n", "");

			if (strParagraph.length() == 0) {
				paraLines.add(strParagraph);
			}
			while (strParagraph.length() > 0) {
				int nSize = mPaint.breakText(strParagraph, true, mVisibleWidth,
						null);
				paraLines.add(strParagraph.substring(0, nSize));
				strParagraph = strParagraph.substring(nSize);
			}
			lines.addAll(0, paraLines);
		}
		while (lines.size() > mLineCount) {
			try {
				m_mbBufBegin  = lines.get(0).getBytes(m_strCharsetName).length;
				lines.remove(0);
			} catch (UnsupportedEncodingException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		m_mbBufEnd = m_mbBufBegin;
		return;
	}

	protected void prePage() throws IOException {
		if (m_mbBufBegin <= 0) {
			m_mbBufBegin = 0;
			m_isfirstPage=true;
			return;
		}else m_isfirstPage=false;
		m_lines.clear();
		pageUp();
		m_lines = pageDown();
	}

	public void nextPage() throws IOException {
		if (m_mbBufEnd >= m_mbBufLen) {
			m_islastPage=true;
			return;
		}else m_islastPage=false;
		m_lines.clear();
		m_mbBufBegin = m_mbBufEnd;
		m_lines = pageDown();
	}

	public void onDraw(Canvas c) {
		if (m_lines.size() == 0)
			m_lines = pageDown();
		if (m_lines.size() > 0) {
			if (m_book_bg == null)
				c.drawColor(m_backColor);
			else
				c.drawBitmap(m_book_bg, 0, 0, null);
			int y = marginHeight;
			for (String strLine : m_lines) {
				y  = m_fontSize;
				c.drawText(strLine, marginWidth, y, mPaint);
			}
		}
		float fPercent = (float) (m_mbBufBegin * 1.0 / m_mbBufLen);
		DecimalFormat df = new DecimalFormat("#0.0");
		String strPercent = df.format(fPercent * 100)   "%";
		int nPercentWidth = (int) mPaint.measureText("999.9%")   1;
		c.drawText(strPercent, mWidth - nPercentWidth, mHeight - 5, mPaint);
	}

	public void setBgBitmap(Bitmap BG) {
		m_book_bg = BG;
	}
	
	public boolean isfirstPage() {
		return m_isfirstPage;
	}
	public boolean islastPage() {
		return m_islastPage;
	}
}