package com.mystudypro.byteutil;

import java.io.UnsupportedEncodingException;

public class ConToByte {

	/**
	 * double轉換byte
	 * @param  arr  byte[]
	 * @param  param    double   double型別的引數
	 * @param  index  int
	 */
	public static void putDouble(byte[] arr, double param, int index) {
		int len = (index - 1) + 8;
        int arrLen = arr.length;
		boolean b = isOutOfArrLength(arrLen, len);   //判斷當前陣列長度是否大於轉換的陣列長度
        Long l = Double.doubleToLongBits(param);
		if (b) { 
			for (int i = 7; i >=0; i--) {
                arr[index + i] = l.byteValue();
				l = l >> 8;
			}
		} else {
            // 如果當前陣列長度小於轉換的陣列長度，就根據index擷取轉換的陣列元素
             l = l>>(8*index);
            for(int j= arrLen-index-1;j>=0;j--){ 
                arr[index+j] = l.byteValue();
                l = l>>8;
            }
        }

	}

	/**
	 * float轉換byte
	 * 
	 * @param  arr   byte[]
	 * @param  param    float  float型別的引數
	 * @param  index  int
	 */
	public static void putFloat(byte[] arr, float param, int index) {
		int len = (index - 1) + 4;
        int arrLen = arr.length;
		boolean b = isOutOfArrLength(arrLen, len);    //判斷當前陣列長度是否大於轉換的陣列長度
        int l = Float.floatToIntBits(param);
		if (b) {
			for (int i = 3; i >=0; i--) {
				arr[index + i] = new Integer(l).byteValue();
				l = l >> 8;
			}
		} else {
            // 如果當前陣列長度小於轉換的陣列長度，就根據index擷取轉換的陣列元素
            l = l>>(8*index);
            for(int j=arrLen-index-1;j>=0;j--){ 
                arr[index+j] =  new Integer(l).byteValue();
                 l =l>>8;
            }
        }

	}

	/**
	 * 字元到位元組轉換
	 * 
	 * @param  arr   byte[]
	 * @param  ch     char   char型別的引數
	 * @param  index   int
	 * @return
	 */
	public static void putChar(byte[] arr, char ch, int index) {
		int len = (index - 1) + 4;
		boolean b = isOutOfArrLength(arr.length, len);      //判斷當前陣列長度是否大於轉換的陣列長度
		if (b) {
			int temp = (int) ch;
			for (int i = 1; i >=0; i--) {
				arr[index + i] = new Integer(temp & 0xff).byteValue();
				temp = temp >> 8;
			}
		}

	}

	/**
	 * 轉換long型為byte陣列
	 * 
	 * @param  arr  byte[]
	 * @param  param    long
	 * @param  index  int
	 */
	public static void putLong(byte[] arr, long param, int index) {
		int len = (index - 1) + 8;
        int arrLen = arr.length;
		boolean b = isOutOfArrLength(arrLen, len);    //判斷當前陣列長度是否大於轉換的陣列長度
		if (b) {
			arr[index + 0] = (byte) ((param >> 56) & 0xff);
			arr[index + 1] = (byte) ((param >> 48) & 0xff);
            arr[index + 2] = (byte) ((param >> 40) & 0xff);
            arr[index + 3] = (byte) ((param >> 32) & 0xff);
            arr[index + 4] = (byte) ((param >> 24) & 0xff);
            arr[index + 5] = (byte) ((param >> 16) & 0xff);
            arr[index + 6] = (byte) ((param >> 8) & 0xff);
            arr[index + 7] = (byte) (param & 0xff);
		} else {
            // 如果當前陣列長度小於轉換的陣列長度，就根據index擷取轉換的陣列元素
            param = param >> (8*index);
              for(int i=arrLen-index-1;i>=0;i--){
                  arr[index+i] =  (byte) (param & 0xff);
                  param = param >> 8;
              }
        }

	}

	/**
	 * int型別轉換成byte陣列
	 * 
	 * @param arr byte[]
	 * @param param  int int型別的引數
	 * @param index  int
	 */
	public static void putInt(byte[] arr, int param, int index) {
		int len = (index - 1) + 4;
		boolean b = isOutOfArrLength(arr.length, len);     //判斷當前陣列長度是否大於轉換的陣列長度
		if (b) {
			arr[index + 0] = (byte) ((param >> 24) & 0xff);
			arr[index + 1] = (byte) ((param >> 16) & 0xff);
			arr[index + 2] = (byte) ((param >> 8) & 0xff);
			arr[index + 3] = (byte) (param & 0xff);
		}
	}

	/**
	 * short型別轉換成byte陣列
	 * 
	 * @param arr   byte[]
	 * @param param  short
	 * @param index  int
	 */
	public static void putShort(byte[] arr, short param, int index) {
		int len = (index - 1) + 2;
		boolean b = isOutOfArrLength(arr.length, len);        //判斷當前陣列長度是否大於轉換的陣列長度
		if (b) { 
			arr[index + 0] = (byte) ((param >> 8) & 0xff);
			arr[index + 1] = (byte) (param & 0xff);
		}
	}

	/**
	 * 字串轉換成byte陣列
	 * 
	 * @param arr  byte[]
	 * @param str  String
	 * @param index  int
	 * @throws java.io.UnsupportedEncodingException
	 */
	public static void putString(byte[] arr, String str, int index) {

		try {
            byte[] bb = str.getBytes("GBK");
			int len = index + bb.length;
			boolean b = isOutOfArrLength(arr.length, len);
			if (b) {
				for (int i = 0; i < bb.length; i++) {
					arr[index + i] = bb[i];
				}
			} else {
                // 如果當前陣列長度小於轉換的陣列長度，就根據index擷取轉換的陣列元素
                for(int j=0;j<arr.length-index;j++){
                    arr[index+j] = bb[j];
                }
            }
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}

	}

	/**
	 * 判斷陣列下標是否越界
	 * 
	 * @param arrLength
	 *            陣列總長度
	 * @param index
	 *            陣列偏移量
	 * @return
	 */
	public static boolean isOutOfArrLength(int arrLength, int index) {
		boolean b;
		if (arrLength > index) {
			b = true;
		} else {
			b = false;
		}
		return b;
	}
}