java基礎資料型別 (Elementary Data Type)轉換成byte[]數組

標籤：

import java.io.UnsupportedEncodingException; 
 
public class ConToByte { 
 
    /**
     * double轉換byte
     * @param  arr  byte[]
     * @param  param    double   double類型的參數
     * @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);   //判斷當前數組長度是否大於轉換的數組長度  
        Long l = Double.doubleToLongBits(param); 
        if (b) {  
            for (int i = 7; i >=0; i--) { 
                arr[index + i] = l.byteValue(); 
                l = l >> 8; 
            } 
        } else { 
            // 如果當前數組長度小於轉換的數組長度，就根據index截取轉換的數組元素  
             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類型的參數
     * @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);    //判斷當前數組長度是否大於轉換的數組長度  
        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 { 
            // 如果當前數組長度小於轉換的數組長度，就根據index截取轉換的數組元素  
            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類型的參數
     * @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);      //判斷當前數組長度是否大於轉換的數組長度  
        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數組
     * 
     * @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);    //判斷當前數組長度是否大於轉換的數組長度  
        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 { 
            // 如果當前數組長度小於轉換的數組長度，就根據index截取轉換的數組元素  
            param = param >> (8*index); 
              for(int i=arrLen-index-1;i>=0;i--){ 
                  arr[index+i] =  (byte) (param & 0xff); 
                  param = param >> 8; 
              } 
        } 
 
    } 
 
    /**
     * int類型轉換成byte數組
     * 
     * @param arr byte[]
     * @param param  int int類型的參數
     * @param index  int
     */ 
    public static void putInt(byte[] arr, int param, int index) { 
        int len = (index - 1) + 4; 
        boolean b = isOutOfArrLength(arr.length, len);     //判斷當前數組長度是否大於轉換的數組長度  
        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類型轉換成byte數組
     * 
     * @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);        //判斷當前數組長度是否大於轉換的數組長度  
        if (b) {  
            arr[index + 0] = (byte) ((param >> 8) & 0xff); 
            arr[index + 1] = (byte) (param & 0xff); 
        } 
    } 
 
    /**
     * 字串轉換成byte數組
     * 
     * @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 { 
                // 如果當前數組長度小於轉換的數組長度，就根據index截取轉換的數組元素  
                for(int j=0;j<arr.length-index;j++){ 
                    arr[index+j] = bb[j]; 
                } 
            } 
        } catch (UnsupportedEncodingException e) { 
            e.printStackTrace(); 
        } 
 
    } 
 
    /**
     * 判斷數組下標是否越界
     * 
     * @param arrLength
     *            數組總長度
     * @param index
     *            數組位移量
     * @return
     */ 
    public static boolean isOutOfArrLength(int arrLength, int index) { 
        boolean b; 
        if (arrLength > index) { 
            b = true; 
        } else { 
            b = false; 
        } 
        return b; 
    } 
} 

java基礎資料型別 (Elementary Data Type)轉換成byte[]數組