PIOUtils.java

package io.mycat.backend.postgresql.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;

/*****
 * PostgreSQL io工具类
 * 
 * @author Coollf
 *
 */
public class PIOUtils {

	public final static Charset UTF8 = Charset.forName("utf-8");

	/**
	 * Sends a 4-byte integer to the back end
	 *
	 * @param val
	 *            the integer to be sent
	 * @exception IOException
	 *                if an I/O error occurs
	 */
	public static void SendInteger4(int val, ByteBuffer buffer) {
		byte[] _int4buf = new byte[4];
		_int4buf[0] = (byte) (val >>> 24);
		_int4buf[1] = (byte) (val >>> 16);
		_int4buf[2] = (byte) (val >>> 8);
		_int4buf[3] = (byte) (val);
		buffer.put(_int4buf);
	}

	public static int redInteger4(ByteBuffer buffer, int offset) {
		return buffer.getInt(offset);
	}
	
	/***
	 * 读取数据
	 * @param buffer
	 * @param offset
	 * @return
	 */
	public static short redInteger2(ByteBuffer buffer, int offset) {
		return buffer.getShort(offset);
	}

	/**
	 * Sends a 2-byte integer (short) to the back end
	 *
	 * @param val
	 *            the integer to be sent
	 * @exception IOException
	 *                if an I/O error occurs or <code>val</code> cannot be
	 *                encoded in 2 bytes
	 */
	public static void SendInteger2(int val, ByteBuffer buffer)
			throws IOException {
		if (val < Short.MIN_VALUE || val > Short.MAX_VALUE)
			throw new IOException(
					"Tried to send an out-of-range integer as a 2-byte value: "
							+ val);

		byte[] _int2buf = new byte[2];
		_int2buf[0] = (byte) (val >>> 8);
		_int2buf[1] = (byte) val;
		buffer.put(_int2buf);
	}

	public static void Send(byte[] encodedParam, ByteBuffer buffer) {
		buffer.put(encodedParam);
	}

	public static void SendChar(int i, ByteBuffer buffer) {
		buffer.put((byte) i);
	}

	/***
	 * 读取数组信息
	 * 
	 * @param buffer
	 * @param offset
	 * @param length
	 * @return
	 */
	public static byte[] redByteArray(ByteBuffer buffer, int offset, int length) {
		byte[] dst = new byte[length];
		for (int i = 0; i < length; i++) {
			dst[i] = buffer.get(offset + i);
		}
		return dst;
	}

	public static void SendString(String string, ByteBuffer buffer) {
		buffer.put(string.getBytes(UTF8));
	}

	public static String redString(ByteBuffer buffer, int offset, Charset charset) throws IOException {
		ByteArrayOutputStream out  =new ByteArrayOutputStream();
		for(int i=offset ;i< buffer.limit();i++){
			out.write(new byte[]{buffer.get(i)});
			if(((char)buffer.get(i)) == '\0'){
				//System.out.println(i - offset);
				break;
			}			
		}
		return new String(out.toByteArray(),charset);
	}

	/**
	 * 读取1byte数据
	 * @param buffer
	 * @param _offset
	 * @return
	 */
	public static byte redInteger1(ByteBuffer buffer, int _offset) {
		return buffer.get(_offset);
	}

	public static void SendByte(byte b, ByteBuffer buffer) {
		buffer.put(b);
	}
	
	

	

}