从包名我们可以看出该类并没有对应用开发者开放，也就是说在google开放的Android API文档中并没有该类的相关介绍；好在Android系统源码是开源的，因此我在解决framework中问题的时候发现了这个工具类，由于工作原因一直没有回头在细细的领会这个工具类的精髓，因此今天花点时间对这个类进行全面的分析一遍，以备不时之需。
首先分析之前，我们需要了解该类使用来进行16禁止转换的，我之前也写过相关的工具类，但是去了解Google的精神还是有必要的。
package com.android.internal.util;
public class HexDump
{
private final static char[] HEX_DIGITS = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘, ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ };//十六进制的组成元素
public static String dumpHexString(byte[] array)
{
return dumpHexString(array, 0, array.length);
}
public static String dumpHexString(byte[] array, int offset, int length)
{
StringBuilder result = new StringBuilder();
byte[] line = new byte[16];
int lineIndex = 0;
result.append("\n0x");
result.append(toHexString(offset));
for (int i = offset ; i < offset + length ; i++)
{
if (lineIndex == 16)
{
result.append(" ");
for (int j = 0 ; j < 16 ; j++)
{
if (line[j] > ‘ ‘ && line[j] < ‘~‘)
{
result.append(new String(line, j, 1));
}
else
{
result.append(".");
}
}
result.append("\n0x");
result.append(toHexString(i));
lineIndex = 0;
}
byte b = array[i];
result.append(" ");
result.append(HEX_DIGITS[(b >>> 4) & 0x0F]);
result.append(HEX_DIGITS[b & 0x0F]);
line[lineIndex++] = b;
}
if (lineIndex != 16)
{
int count = (16 - lineIndex) * 3;
count++;
for (int i = 0 ; i < count ; i++)
{
result.append(" ");
}
for (int i = 0 ; i < lineIndex ; i++)
{
if (line[i] > ‘ ‘ && line[i] < ‘~‘)
{
result.append(new String(line, i, 1));
}
else
{
result.append(".");
}
}
}
return result.toString();
}
public static String toHexString(byte b)
{
return toHexString(toByteArray(b));
}
public static String toHexString(byte[] array)
{
return toHexString(array, 0, array.length);
}
public static String toHexString(byte[] array, int offset, int length)
{
char[] buf = new char[length * 2];
int bufIndex = 0;
for (int i = offset ; i < offset + length; i++)
{
byte b = array[i];
buf[bufIndex++] = HEX_DIGITS[(b >>> 4) & 0x0F];
buf[bufIndex++] = HEX_DIGITS[b & 0x0F];
}
return new String(buf);
}
public static String toHexString(int i)
{
return toHexString(toByteArray(i));
}
public static byte[] toByteArray(byte b)
{
byte[] array = new byte[1];
array[0] = b;
return array;
}
public static byte[] toByteArray(int i)
{
byte[] array = new byte[4];
array[3] = (byte)(i & 0xFF);
array[2] = (byte)((i >> 8) & 0xFF);
array[1] = (byte)((i >> 16) & 0xFF);
array[0] = (byte)((i >> 24) & 0xFF);
return array;
}
private static int toByte(char c)
{
if (c >= ‘0‘ && c <= ‘9‘) return (c - ‘0‘);
if (c >= ‘A‘ && c <= ‘F‘) return (c - ‘A‘ + 10);
if (c >= ‘a‘ && c <= ‘f‘) return (c - ‘a‘ + 10);
throw new RuntimeException ("Invalid hex char ‘" + c + "‘");
}
public static byte[] hexStringToByteArray(String hexString)
{
int length = hexString.length();
byte[] buffer = new byte[length / 2];
for (int i = 0 ; i < length ; i += 2)
{
buffer[i / 2] = (byte)((toByte(hexString.charAt(i)) << 4) | toByte(hexString.charAt(i+1)));
}
return buffer;
}
}