Java基本数据位运算

byte[ ]与常用基本数据类型的转换

import java.util.Arrays; /** * byte[]与常用基本数据类型的转换工具类 */ public class BitOperation { private static final char[] hexArray = "0123456789ABCDEF".toCharArray(); /** * 十六进制字符串转byte[] * @param values 16进制String(一个字符2字节) * @return */ public static byte[] hexStrToBytes(String values) { if (values == null || values.trim().equals("")) { return new byte[0]; } byte[] result = new byte[values.length() / 2]; for (int i = 0; i < result.length; i++) { String subStr = values.substring(i * 2, i * 2 + 2); result[i] = (byte) Integer.parseInt(subStr, 16); } return result; } /** * byte[]转十六进制字符串 * * @param values 16进制String(一个字符2字节) * @return */ public static String bytesToHexStr(byte[] values) { char[] hexChars = new char[values.length * 2]; for ( int j = 0; j < values.length; j++ ) { int v = values[j] & 0xFF; hexChars[j * 2] = hexArray[v >>> 4]; hexChars[j * 2 + 1] = hexArray[v & 0x0F]; } return new String(hexChars); } /** * Long型转byte[] * * @param values long(8字节) * @return */ public static byte[] longToBytes(long values){ byte[] result = new byte[8]; int temp; for (int i = 0; i < 8; i++){ temp = (8 - 1 - i) * 8; result[i] = (byte) ((values >>> temp) & 0xFF); } return result; } /** * byte[]转Long型 * * @param values long(8字节) * @return */ public static long bytesToLong(byte[] values){ long result = 0; for (int i = 0; i < 8; i++) { result <<= 8; result |= (values[i] & 0xff); } return result; } /** * int型转byte[] * * @param values int(4字节) * @return */ public static byte[] intToBytes(int values){ byte[] result = new byte[4]; int temp; for (int i = 0; i < 4; i++){ temp = (4 - 1 - i) * 8; result[i] = (byte) ((values >>> temp) & 0xFF); } return result; } /** * byte[]转int型 * * @param values int(4字节) * @return */ public static int bytesToInt(byte[] values){ int result = 0; for (int i = 0; i < 4; i++) { result <<= 8; result |= (values[i] & 0xff); } return result; } /** * short转byte[] * * @param values short(2字节) * @return */ public static byte[] shortToByte(short values){ byte[] result = new byte[2]; result[0] = (byte) (values >>> 8 & 0xFF); result[1] = (byte) (values & 0xFF); return result; } /** * byte[]转short * * @param values short(2字节) * @return */ public static short bytesToShort(byte[] values){ return (short) (values[0] | (values[1] << 8)); } /** * char转byte[] * * @param values char(2字节) * @return */ public static byte[] charToBytes(char values){ byte[] result = new byte[2]; result[0] = (byte) (values & 0xFF); result[1] = (byte) ((values << 8) & 0xFF); return result; } /** * char转byte[] * * @param values char(2字节) * @return */ public static char bytesToChar(byte[] values){ return (char) (values[0] | (values[1] << 8)); } /** * int整型转指定长度byte[] * * @param values 要转换的数据 * * @param len 转换成byte[]后的长度 * @return */ public static byte[] intToBytes(int values, int len){ byte[] result = new byte[len]; int temp; for (int i = 0; i < len; i++){ temp = (len - 1 - i) * 8; result[i] = (byte) ((values >>> temp) & 0xFF); } return result; } /** * byte[]转指定长度int整型 * * @param values 要转换的数据 * * @param len 转换成int整型后的长度，取字节数组长度即可。 * @return */ public static int bytesToInt(byte[] values, int len){ int result = 0; for (int i = 0; i < len; i++) { result <<= 8; result |= (values[i] & 0xff); } return result; } public static void main(String[] args){ int a = 519; System.out.println("int转byte[]=" + Arrays.toString(intToBytes(a, 3))); System.out.println("byte[]转int=" + bytesToInt(intToBytes(a, 3), intToBytes(a, 3).length)); } }

另外还有一个比较简单的转换方法，使用的是ByteBuffer类(涉及到一个大端小端问题)出处：

import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.charset.Charset; import java.util.Arrays; public class BigByteUtil { /** * short 转 byte[] * 大端 * @param data * @return */ public static byte[] getShortBytes(short data) { ByteBuffer buffer = ByteBuffer.allocate(2); buffer.order(ByteOrder.BIG_ENDIAN); buffer.putShort(data); return buffer.array(); } /** * chart 转 byte[] * 大端 * @param data * @return */ public static byte[] getCharBytes(char data) { ByteBuffer buffer = ByteBuffer.allocate(2); buffer.order(ByteOrder.BIG_ENDIAN); buffer.putChar(data); return buffer.array(); } /** * int 转 byte[] * 大端 * @param data * @return */ public static byte[] getIntBytes(int data) { ByteBuffer buffer = ByteBuffer.allocate(4); buffer.order(ByteOrder.BIG_ENDIAN); buffer.putInt(data); return buffer.array(); } /** * long 转 byte[] * 大端 * @param data * @return */ public static byte[] getLongBytes(long data) { ByteBuffer buffer = ByteBuffer.allocate(8); buffer.order(ByteOrder.BIG_ENDIAN); buffer.putLong(data); return buffer.array(); } /** * float 转 byte[] * 大端 * @param data * @return */ public static byte[] getFloatBytes(float data) { ByteBuffer buffer = ByteBuffer.allocate(4); buffer.order(ByteOrder.BIG_ENDIAN); buffer.putFloat(data); return buffer.array(); } /** * double 转 byte[] * 大端 * @param data * @return */ public static byte[] getDoubleBytes(double data) { ByteBuffer buffer = ByteBuffer.allocate(8); buffer.order(ByteOrder.BIG_ENDIAN); buffer.putDouble(data); return buffer.array(); } /** * String 转 byte[] * * @param data * @param charsetName * @return */ public static byte[] getStringBytes(String data, String charsetName) { Charset charset = Charset.forName(charsetName); return data.getBytes(charset); } /** * String 转 byte[] * * @param data * @return */ public static byte[] getStringBytes(String data) { byte[] bytes = null; if(data != null){ bytes = data.getBytes(); }else{ bytes = new byte[0]; } return bytes; } /*****************************************************************************************************************************/ /** * byte[] 转short * 大端 * @param bytes * @return */ public static short getShort(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(bytes.length); buffer.order(ByteOrder.BIG_ENDIAN); buffer.put(bytes); return buffer.getShort(0); } /** * byte[] 转 char * 大端 * @param bytes * @return */ public static char getChar(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(bytes.length); buffer.order(ByteOrder.BIG_ENDIAN); buffer.put(bytes); return buffer.getChar(0); } /** * byte[] 转 int * 大端 * @param bytes * @return */ public static int getInt(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(bytes.length); buffer.order(ByteOrder.BIG_ENDIAN); buffer.put(bytes); return buffer.getInt(0); } /** * byte[] 转 long * * @param bytes * @return */ public static long getLong(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(bytes.length); buffer.order(ByteOrder.BIG_ENDIAN); buffer.put(bytes); return buffer.getLong(0); } /** * byte[] 转 float * * @param bytes * @return */ public static float getFloat(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(bytes.length); buffer.order(ByteOrder.BIG_ENDIAN); buffer.put(bytes); return buffer.getFloat(0); } /** * byte[] 转 double * * @param bytes * @return */ public static double getDouble(byte[] bytes) { ByteBuffer buffer = ByteBuffer.allocate(bytes.length); buffer.order(ByteOrder.BIG_ENDIAN); buffer.put(bytes); return buffer.getDouble(0); } /** * byte[] 转 String * * @param bytes * @param charsetName * @return */ public static String getString(byte[] bytes, String charsetName) { return new String(bytes, Charset.forName(charsetName)); } /** * byte[] 转 String * * @param bytes * @return */ public static String getString(byte[] bytes) { return new String(bytes); } public static void main(String[] args){ String str = "0123456789abcde"; long l = 6699; int i = 2233; short s = Short.MAX_VALUE; char c = 'c'; System.out.println("？转byte[]=" + Arrays.toString(getCharBytes(c))); System.out.println("byte[]转？=" + getChar(getCharBytes(c))); } }

因为项目需要，对数据类型与byte[]进行互转，所以最新学习了总结了一下。以上方法测试没有问题(16进制字符串的转换有点问题)，不过在此有一个问题想了一天也没想通，希望哪位大神看见了解答一下（感谢^_^）： 在用以上16进制字符串转byte[ ]时，string长度为偶数时没问题，但如果string长度为奇数，则转过来的byte[ ]会少一个字节，反转也会少一个字符，因为for循环中使用的长度是string的长度，又因长度是int型，除2会直接取整，所以导致少循环了一次，截取时是截取的两个，在长度为偶数时就算少循环一次也正好可以截取完数据，所以导致在长度为偶数时没问题，长度为奇数时就会少一个字节或字符。而我百度到的转换全都是这样的，搞得我有点蒙圈。