一个处理整数的类代码,Java代码库,德仔网

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【Java】一个处理整数的类
作者: / 发布于2011/1/3/ 374
处理整数
import java.io.*;
import java.nio.*;

public final class IntegerUtil 
{
 private static final String digits = "0123456789abcdef";
 

 /**
 * converts byte array to integer. byte array shall be of size 4 (32 bit)
 */
 public static final int getInt(byte[] bytes) throws IOException
 {
 if(bytes==null || bytes.length!=4)
 {
 throw new IllegalArgumentException("Illegal Byte Array");
 }
 ByteBuffer buf = ByteBuffer.allocate(bytes.length);
 buf=buf.put(bytes);
 return buf.getInt(0);

 }

 /**
 * return integer array view for a given byte array. If byte array length is not divisible by 4 then there is possibility of loosing last bytes.
 * for e.g if byte array size is 5 then it ignores 5th byte in getting integer array.
 */
 public static int[] getIntegerArray(byte[] bytes) throws IOException
 {
 if(bytes==null)
 {
 throw new IllegalArgumentException("Illegal Byte Array");
 }
 ByteBuffer buf = ByteBuffer.allocate(bytes.length);
 buf=buf.put(bytes); 
 buf=(ByteBuffer)buf.rewind();
 IntBuffer intBuffer=buf.asIntBuffer();
 intBuffer=(IntBuffer)intBuffer.rewind();
 int []array=new int[bytes.length/4]; 
 for(int i=0;i<array.length;i++)
 {
 array[i]=intBuffer.get(i); 
 }
 
 return array;
 }

 
 /**
 * gets the Integer from ByteBuffer. ByteBuffer shall contain only 4 bytes
 */
 public static final int getInt(ByteBuffer buf) throws IOException
 {
 if(buf==null || buf.array().length!=4)
 {
 throw new IllegalArgumentException("Illegal Byte Buffer");
 }
 return buf.getInt(0);
 }

 /**
 * return a byte value for a given position from integer
 */
 
 public static final byte getByte(int i, int pos) throws IOException
 {
 if(pos<0 || pos>3)
 {
 throw new IllegalArgumentException("Illegal Position "+pos);
 }
 return getBytes(i)[pos];
 }
 
 /**
 * converts integer to byte array
 */
 public static final byte[] getBytes(int i) throws IOException
 {
 return getByteBuffer(i).array();
 }

 /**
 * Creates ByteBuffer Wrapper for a given integer
 */
 public static final ByteBuffer getByteBuffer(int i) throws IOException
 {
 ByteBuffer buf = ByteBuffer.allocate(4);
 buf=buf.putInt(i);
 return buf;
 }

 /**
 * Creates ByteBuffer Wrapper for a given integer. ByteBuffer would be either direct or non-direct based on the flag
 */
 public static final ByteBuffer getByteBuffer(int i, boolean bDirectBuffer) throws IOException
 {
 ByteBuffer buf = null;
 if(bDirectBuffer==false)
 {
 buf=ByteBuffer.allocate(4);
 }
 else
 {
 buf=ByteBuffer.allocateDirect(4);
 }
 buf=buf.putInt(i);
 return buf;
 }
 
 /**
 * returns byte array as ByteBuffer. byte array size shall be 4 (32 bit)
 */
 public static final ByteBuffer getByteBuffer(byte[] bytes) throws IOException
 {
 if(bytes==null || bytes.length!=4)
 {
 throw new IllegalArgumentException("Illegal Byte Array");
 }
 return ByteBuffer.wrap(bytes); 
 }



 /**
 * Converts integer to Hexa-Decimal String
 */
 public static final String intToHex(int i)
 {
 return Integer.toHexString(i);
 }
 /**
 * Converts integer to binary String
 */
 public static final String intToBinary(int i)
 {
 return Integer.toBinaryString(i);
 }
 /**
 * Converts integer to Octal String
 */
 public static final String intToOctal(int i)
 {
 return Integer.toOctalString(i);
 }

 /**
 * Converts Hexa-Decimal String to integer
 */

 public static final int hexToInt(String s)
 {
 return Integer.parseInt(s,16);
 }
 /**
 * Converts Binary String to integer
 */
 public static final int binaryToInt(String s)
 {
 return Integer.parseInt(s,2);
 }
 /**
 * Converts Octal String to integer
 */
 public static final int octalToInt(String s)
 {
 return Integer.parseInt(s,8);
 }
 /**
 * Converts byte array to Hexa-Decimal String
 */
 public static final String toHex(byte[] data) throws IOException
 {
 if(data.length!=4)
 {
 throw new IllegalArgumentException("Illegal Byte Array");
 }
 return intToHex(getInt(data));
 }
 /**
 * returns the hexa-decimal string for a given ByteBuffer
 */
 public static final String toHex(ByteBuffer buffer) throws IOException
 {
 if(buffer==null || buffer.array().length!=4)
 {
 throw new IllegalArgumentException("Illegal Byte Buffer");
 }
 return intToHex(getInt(buffer));
 }
 
 /**
 * Converts byte array to Hexa-Decimal String
 */
 public static final String toHex(byte[] data, int length)
 {
 if(length!=4)
 {
 throw new IllegalArgumentException("Illegal Length");
 }
 StringBuffer buf = new StringBuffer(); 
 for (int i = 0; i != length; i++)
 {
 int v = data[i] & 0xff;
 
 buf.append(digits.charAt(v >> 4));
 buf.append(digits.charAt(v & 0xf));
 }
 
 return buf.toString();
 }
 /**
 * Converts integer to byte array
 */
 public static final byte[] intToByteArray(int value) {
 return new byte[] {
 (byte)(value >>> 24),
 (byte)(value >>> 16),
 (byte)(value >>> 8),
 (byte)value};
 }

 /**
 * Converts byte array to integer 
 */
 public static final int byteArrayToInt(byte [] b) {
 return (b[0] << 24)
 + ((b[1] & 0xFF) << 16)
 + ((b[2] & 0xFF) << 8)
 + (b[3] & 0xFF);
 }

 public static int hex2decimal(String s) {
 String digits = "0123456789ABCDEF";
 s = s.toUpperCase();
 int val = 0;
 for (int i = 0; i < s.length(); i++) {
 char c = s.charAt(i);
 int d = digits.indexOf(c);
 val = 16*val + d;
 }
 return val;
 }

 
 // precondition: d is a nonnegative integer
 public static String decimal2hex(int d) {
 String digits = "0123456789ABCDEF";
 if (d == 0) return "0";
 String hex = ""; 
 while (d > 0) {
 int digit = d % 16; // rightmost digit
 hex = digits.charAt(digit) + hex; // string concatenation
 d = d / 16;
 }
 return hex;
 }


 public static String hexToString(String input, int groupLength) {
 StringBuilder sb = new StringBuilder(input.length() / groupLength);

 for (int i = 0; i < input.length() - groupLength + 1; i += groupLength) {
 String hex = input.substring(i, i + groupLength);
 sb.append((char) Integer.parseInt(hex, 16));
 }

 return sb.toString();
 }

} 
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