buffer.java

基于java的oa系统

/*
 Copyright (C) 2002-2004 MySQL AB

 This program is free software; you can redistribute it and/or modify
 it under the terms of version 2 of the GNU General Public License as
 published by the Free Software Foundation.
 

 There are special exceptions to the terms and conditions of the GPL 
 as it is applied to this software. View the full text of the 
 exception exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
 software distribution.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */
package com.mysql.jdbc;

import java.io.UnsupportedEncodingException;
import java.sql.SQLException;


/**
 * Buffer contains code to read and write packets from/to the MySQL server.
 *
 * @version $Id: Buffer.java,v 1.15.2.18 2004/10/21 19:31:04 mmatthew Exp $
 * @author Mark Matthews
 */
class Buffer {
    static final int NO_LENGTH_LIMIT = -1;
    static final long NULL_LENGTH = -1;
    private byte[] byteBuffer;
    private boolean wasMultiPacket = false;
    private int bufLength = 0;
    private int position = 0;
    private int sendLength = 0;

    Buffer(byte[] buf) {
        this.byteBuffer = buf;
        setBufLength(buf.length);
    }

    Buffer(int size) {
        this.byteBuffer = new byte[size];
        setBufLength(this.byteBuffer.length);
        this.position = MysqlIO.HEADER_LENGTH;
    }

    /**
     * Sets the array of bytes to use as a buffer to read from.
     *
     * @param byteBuffer the array of bytes to use as a buffer
     */
    public void setByteBuffer(byte[] byteBuffer) {
        this.byteBuffer = byteBuffer;
    }

    /**
     * Returns the array of bytes this Buffer is using to read from.
     *
     * @return byte array being read from
     */
    public byte[] getByteBuffer() {
        return this.byteBuffer;
    }

    /**
     * Set the current position to write to/ read from
     *
     * @param position the position (0-based index)
     */
    public void setPosition(int position) {
        this.position = position;
    }

    /**
     * Returns the current position to write to/ read from
     *
     * @return the current position to write to/ read from
     */
    public int getPosition() {
        return this.position;
    }

    /**
     * Sets whether this packet was part of a multipacket
     *
     * @param flag was this packet part of a multipacket?
     */
    public void setWasMultiPacket(boolean flag) {
        wasMultiPacket = flag;
    }

    /**
     * Skip over a length-encoded string
     *
     * @return The position past the end of the string
     */
    public int fastSkipLenString() {
        long len = this.readFieldLength();

        position += len;

        return (int) len; // this is safe, as this is only
    }

    /**
     * Was this packet part of a multipacket?
     *
     * @return was this packet part of a multipacket?
     */
    public boolean wasMultiPacket() {
        return wasMultiPacket;
    }

    protected final byte[] getBufferSource() {
        return byteBuffer;
    }

    final byte[] getBytes(int len) {
        byte[] b = new byte[len];
        System.arraycopy(this.byteBuffer, this.position, b, 0, len);
        this.position += len; // update cursor

        return b;
    }

    // 2000-06-05 Changed
    final boolean isLastDataPacket() {
        return ((getBufLength() < 9) && ((this.byteBuffer[0] & 0xff) == 254));
    }

    final void clear() {
        this.position = MysqlIO.HEADER_LENGTH;
    }

    final void dump() {
    	StringUtils.dumpAsHex(this.byteBuffer, getBufLength());
    }

    final void dumpHeader() {
        for (int i = 0; i < MysqlIO.HEADER_LENGTH; i++) {
            String hexVal = Integer.toHexString((int) this.byteBuffer[i] & 0xff);

            if (hexVal.length() == 1) {
                hexVal = "0" + hexVal;
            }

            System.out.print(hexVal + " ");
        }
    }

    final void dumpNBytes(int start, int nBytes) {
        StringBuffer asciiBuf = new StringBuffer();

        for (int i = start;
                (i < (start + nBytes)) && (i < this.byteBuffer.length); i++) {
            String hexVal = Integer.toHexString((int) this.byteBuffer[i] & 0xff);

            if (hexVal.length() == 1) {
                hexVal = "0" + hexVal;
            }

            System.out.print(hexVal + " ");

            if ((this.byteBuffer[i] > 32) && (this.byteBuffer[i] < 127)) {
                asciiBuf.append((char) this.byteBuffer[i]);
            } else {
                asciiBuf.append(".");
            }

            asciiBuf.append(" ");
        }

        System.out.println("    " + asciiBuf.toString());
    }

    final void ensureCapacity(int additionalData) throws SQLException {
        if ((this.position + additionalData) > getBufLength()) {
            if ((this.position + additionalData) < this.byteBuffer.length) {
                // byteBuffer.length is != getBufLength() all of the time
                // due to re-using of packets (we don't shrink them)
                //
                // If we can, don't re-alloc, just set buffer length 
                // to size of current buffer
                setBufLength(this.byteBuffer.length);
            } else {
                //
                // Otherwise, re-size, and pad so we can avoid
                // allocing again in the near future
                //
                int newLength = (int) (this.byteBuffer.length * 1.25);

                if (newLength < (this.byteBuffer.length + additionalData)) {
                    newLength = this.byteBuffer.length
                        + (int) (additionalData * 1.25);
                }

                if (newLength < this.byteBuffer.length) {
                    newLength = this.byteBuffer.length + additionalData;
                }

                byte[] newBytes = new byte[newLength];

                System.arraycopy(this.byteBuffer, 0, newBytes, 0,
                    this.byteBuffer.length);
                this.byteBuffer = newBytes;
                setBufLength(this.byteBuffer.length);
            }
        }
    }

    final long newReadLength() {
        int sw = this.byteBuffer[this.position++] & 0xff;

        switch (sw) {
        case 251:
            return (long) 0;

        case 252:
            return (long) readInt();

        case 253:
            return (long) readLongInt();

        case 254: // changed for 64 bit lengths
            return (long) readLongLong();

        default:
            return (long) sw;
        }
    }

    final byte readByte() {
        return this.byteBuffer[this.position++];
    }

    final long readFieldLength() {
        int sw = this.byteBuffer[this.position++] & 0xff;

        switch (sw) {
        case 251:
            return NULL_LENGTH;

        case 252:
            return (long) readInt();

        case 253:
            return (long) readLongInt();

        case 254:
            return readLongLong();

        default:
            return (long) sw;
        }
    }

    // 2000-06-05 Changed
    final int readInt() {
        byte[] b = this.byteBuffer; // a little bit optimization

        return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8);
    }

    final byte[] readLenByteArray(int offset) {
        long len = this.readFieldLength();

        if (len == NULL_LENGTH) {
            return null;
        }

        if (len == 0) {
            return new byte[0];
        }

        this.position += offset;

        return getBytes((int) len);
    }

    final long readLength() {
        int sw = this.byteBuffer[this.position++] & 0xff;

        switch (sw) {
        case 251:
            return (long) 0;

        case 252:
            return (long) readInt();

        case 253:
            return (long) readLongInt();

        case 254:
            return (long) readLong();

        default:
            return (long) sw;
        }
    }

    // 2000-06-05 Fixed
    final long readLong() {
        byte[] b = this.byteBuffer;

        return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8)
        | ((b[this.position++] & 0xff) << 16)
        | ((b[this.position++] & 0xff) << 24);
    }

    // 2000-06-05 Changed
    final int readLongInt() {
        byte[] b = this.byteBuffer;

        return (b[this.position++] & 0xff) | ((b[this.position++] & 0xff) << 8)
        | ((b[this.position++] & 0xff) << 16);
    }

    // 2000-06-05 Fixed
    final long readLongLong() {
        byte[] b = this.byteBuffer;

        return (long) (b[this.position++] & 0xff)
        | ((long) (b[this.position++] & 0xff) << 8)
        | ((long) (b[this.position++] & 0xff) << 16)
        | ((long) (b[this.position++] & 0xff) << 24)
        | ((long) (b[this.position++] & 0xff) << 32)
        | ((long) (b[this.position++] & 0xff) << 40)
        | ((long) (b[this.position++] & 0xff) << 48)
        | ((long) (b[this.position++] & 0xff) << 56);
    }

    //
    // Read a null-terminated string
    //
    // To avoid alloc'ing a new byte array, we
    // do this by hand, rather than calling getNullTerminatedBytes()
    //
    final String readString() {
        int i = this.position;
        int len = 0;
		int maxLen = getBufLength();
		
        while ((i < maxLen) && (this.byteBuffer[i] != 0)) {
            len++;
            i++;
        }

        String s = new String(this.byteBuffer, this.position, len);
        this.position += (len + 1); // update cursor

        return s;
    }
    
    final String readString(String encoding) throws SQLException {
		int i = this.position;
		int len = 0;
		int maxLen = getBufLength();
		
		while ((i < maxLen) && (this.byteBuffer[i] != 0)) {
			len++;
			i++;
		}

		try {
			return new String(this.byteBuffer, this.position, len, encoding);
			
		} catch (UnsupportedEncodingException uEE) {
			throw new SQLException("Unsupported character encoding '" + encoding + "'", SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
		} finally {
			this.position += (len + 1); // update cursor
		}
    }

    final int readnBytes() {
        int sw = this.byteBuffer[this.position++] & 0xff;

        switch (sw) {
        case 1:
            return this.byteBuffer[this.position++] & 0xff;

        case 2:
            return this.readInt();

        case 3:
            return this.readLongInt();

        case 4:
            return (int) this.readLong();

        default:
            return 255;
        }
    }

    final void writeByte(byte b) throws SQLException {
        ensureCapacity(1);

        this.byteBuffer[this.position++] = b;
    }

    // Write a byte array
    final void writeBytesNoNull(byte[] bytes) throws SQLException {
        int len = bytes.length;
        ensureCapacity(len);
        System.arraycopy(bytes, 0, this.byteBuffer, this.position, len);
        this.position += len;
    }

    // Write a byte array with the given offset and length
    final void writeBytesNoNull(byte[] bytes, int offset, int length)
        throws SQLException {
        ensureCapacity(length);
        System.arraycopy(bytes, offset, this.byteBuffer, this.position, length);
        this.position += length;
    }

    final void writeDouble(double d) {
        long l = Double.doubleToLongBits(d);
        writeLongLong(l);
    }

    final void writeFloat(float f) {
        int i = Float.floatToIntBits(f);
        byte[] b = this.byteBuffer;
        b[this.position++] = (byte) (i & 0xff);
        b[this.position++] = (byte) (i >>> 8);
        b[this.position++] = (byte) (i >>> 16);
        b[this.position++] = (byte) (i >>> 24);
    }

    // 2000-06-05 Changed
    final void writeInt(int i) {
        byte[] b = this.byteBuffer;
        b[this.position++] = (byte) (i & 0xff);
        b[this.position++] = (byte) (i >>> 8);
    }

    // 2000-06-05 Changed
    final void writeLong(long i) {
        byte[] b = this.byteBuffer;
        b[this.position++] = (byte) (i & 0xff);
        b[this.position++] = (byte) (i >>> 8);
        b[this.position++] = (byte) (i >>> 16);
        b[this.position++] = (byte) (i >>> 24);
    }

    // 2000-06-05 Changed
    final void writeLongInt(int i) {
        byte[] b = this.byteBuffer;
        b[this.position++] = (byte) (i & 0xff);
        b[this.position++] = (byte) (i >>> 8);
        b[this.position++] = (byte) (i >>> 16);
    }

    final void writeLongLong(long i) {
        byte[] b = this.byteBuffer;
        b[this.position++] = (byte) (i & 0xff);
        b[this.position++] = (byte) (i >>> 8);
        b[this.position++] = (byte) (i >>> 16);
        b[this.position++] = (byte) (i >>> 24);
        b[this.position++] = (byte) (i >>> 32);
        b[this.position++] = (byte) (i >>> 40);
        b[this.position++] = (byte) (i >>> 48);
        b[this.position++] = (byte) (i >>> 56);
    }

    // Write null-terminated string
    final void writeString(String s) throws SQLException {
    	ensureCapacity(s.length() + 1);
    	
        writeStringNoNull(s);
        this.byteBuffer[this.position++] = 0;
    }

    // Write string, with no termination
    final void writeStringNoNull(String s) throws SQLException {
        int len = s.length();
        ensureCapacity(len);
        System.arraycopy(s.getBytes(), 0, byteBuffer, position, len);
        position += len;

        //         for (int i = 0; i < len; i++)
        //         {
        //             this.byteBuffer[this.position++] = (byte)s.charAt(i);
        //         }
    }

    // Write a String using the specified character
    // encoding
    final void writeStringNoNull(String s, String encoding, String serverEncoding, 
    		SingleByteCharsetConverter converter, boolean parserKnowsUnicode)
        throws UnsupportedEncodingException, SQLException {
        byte[] b = null;
        
        if (converter != null) {
            b = converter.toBytes(s);
        } else {
            b = StringUtils.getBytes(s, encoding, serverEncoding, parserKnowsUnicode);
        }

        int len = b.length;
        ensureCapacity(len);
        System.arraycopy(b, 0, this.byteBuffer, this.position, len);
        this.position += len;
    }

    void setBufLength(int bufLength) {
        this.bufLength = bufLength;
    }

    int getBufLength() {
        return bufLength;
    }

    void setSendLength(int sendLength) {
        this.sendLength = sendLength;
    }
}