java中基本数据类型和C语言中基本数据类型转换
java中
1 short = 2 byte
1 char = 2 byte
1 int = 4 byte
1 long = 8 byte
C语言中
typedef unsigned char byte;
在32 位的系统上short 咔出来的内存大小是2 个byte；
int 咔出来的内存大小是4 个byte；
long 咔出来的内存大小是4 个byte；
float 咔出来的内存大小是4 个byte；
double 咔出来的内存大小是8 个byte；
char 咔出来的内存大小是1 个byte。
（注意这里指一般情况，可能不同的平台还会有所不同，具体平台可以用sizeof 关键字测试一下）
import java.nio.ByteOrder;
public class BytesTransUtils {
private String TAG = "BytesTransUtils";
private static BytesTransUtils instance = null;
private BytesTransUtils() {
// Log.i(TAG, "instance BytesTransUtils");
}
public static BytesTransUtils getInstance() {
if (instance == null) {
instance = new BytesTransUtils();
}
return instance;
}
public boolean testCPU() {
if (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN) {
// System.out.println("is big ending");
return true;
} else {
// System.out.println("is little ending");
return false;
}
}
public byte[] getBytes(short s, boolean bBigEnding) {
byte[] buf = new byte[2];
if (bBigEnding){
for (int i = buf.length - 1; i >= 0; i--) {
buf[i] = (byte) (s & 0x00ff);
s >>= 8;
}
}
else {
for (int i = 0; i < buf.length; i++) {
buf[i] = (byte) (s & 0x00ff);
s >>= 8;
}
}
return buf;
}
public byte[] getBytes(int s, boolean bBigEnding) {
byte[] buf = new byte[4];
if (bBigEnding) {
for (int i = buf.length - 1; i >= 0; i--) {
buf[i] = (byte) (s & 0x000000ff);
s >>= 8;
}
} else {
System.out.println("1");
for (int i = 0; i < buf.length; i++) {
buf[i] = (byte) (s & 0x000000ff);
s >>= 8;
}
}
return buf;
}
public byte[] getBytes(long s, boolean bBigEnding) {
byte[] buf = new byte[8];
if (bBigEnding) {
for (int i = buf.length - 1; i >= 0; i--) {
buf[i] = (byte) (s & 0x00000000000000ff);
s >>= 8;
}
}
else {
for (int i = 0; i < buf.length; i++) {
buf[i] = (byte) (s & 0x00000000000000ff);
s >>= 8;
}
}
return buf;
}
public short getShort(byte[] buf, boolean bBigEnding) {
if (buf == null) {
throw new IllegalArgumentException("byte array is null!");
}
if (buf.length > 2) {
throw new IllegalArgumentException("byte array size > 2 !");
}
short r = 0;
if (bBigEnding) {
for (int i = 0; i < buf.length; i++) {
r <<= 8;
r |= (buf[i] & 0x00ff);
}
} else {
for (int i = buf.length - 1; i >= 0; i--) {
r <<= 8;
r |= (buf[i] & 0x00ff);
}
}
return r;
}
public int getInt(byte[] buf, boolean bBigEnding) {
if (buf == null) {
throw new IllegalArgumentException("byte array is null!");
}
if (buf.length > 4) {
throw new IllegalArgumentException("byte array size > 4 !");
}
int r = 0;
if (bBigEnding) {
for (int i = 0; i < buf.length; i++) {
r <<= 8;
r |= (buf[i] & 0x000000ff);
}
} else {
for (int i = buf.length - 1; i >= 0; i--) {
r <<= 8;
r |= (buf[i] & 0x000000ff);
}
}
return r;
}
public long getLong(byte[] buf, boolean bBigEnding) {
if (buf == null) {
throw new IllegalArgumentException("byte array is null!");
}
if (buf.length > 8) {
throw new IllegalArgumentException("byte array size > 8 !");
}
long r = 0;
if (bBigEnding) {
for (int i = 0; i < buf.length; i++) {
r <<= 8;
r |= (buf[i] & 0x00000000000000ff);
}
} else {
for (int i = buf.length - 1; i >= 0; i--) {
r <<= 8;
r |= (buf[i] & 0x00000000000000ff);
}
}
return r;
}
/*----------------------------------------------------------*/
/* 对转换进行一个简单的封装 */
/*----------------------------------------------------------*/
public byte[] getBytes(int i) {
return getBytes(i, this.testCPU());
}
public byte[] getBytes(short s) {
return getBytes(s, this.testCPU());
}
public byte[] getBytes(long l) {
return getBytes(l, this.testCPU());
}
public int getInt(byte[] buf) {
return getInt(buf, this.testCPU());
}
public short getShort(byte[] buf) {
return getShort(buf, this.testCPU());
}
public long getLong(byte[] buf) {
return getLong(buf, this.testCPU());
}
/****************************************/
public short[] Bytes2Shorts(byte[] buf) {
byte bLength = 2;
short[] s = new short[buf.length / bLength];
for (int iLoop = 0; iLoop < s.length; iLoop++) {
byte[] temp = new byte[bLength];
for (int jLoop = 0; jLoop < bLength; jLoop++) {
temp[jLoop] = buf[iLoop * bLength + jLoop];
}
s[iLoop] = getShort(temp);
}
return s;
}
public byte[] Shorts2Bytes(short[] s) {
byte bLength = 2;
byte[] buf = new byte[s.length * bLength];
for (int iLoop = 0; iLoop < s.length; iLoop++) {
byte[] temp = getBytes(s[iLoop]);
for (int jLoop = 0; jLoop < bLength; jLoop++) {
buf[iLoop * bLength + jLoop] = temp[jLoop];
}
}
return buf;
}
/****************************************/
public int[] Bytes2Ints(byte[] buf) {
byte bLength = 4;
int[] s = new int[buf.length / bLength];
for (int iLoop = 0; iLoop < s.length; iLoop++) {
byte[] temp = new byte[bLength];
for (int jLoop = 0; jLoop < bLength; jLoop++) {
temp[jLoop] = buf[iLoop * bLength + jLoop];
}
s[iLoop] = getInt(temp);
System.out.println("2out->"+s[iLoop]);
}
return s;
}
public byte[] Ints2Bytes(int[] s) {
byte bLength = 4;
byte[] buf = new byte[s.length * bLength];
for (int iLoop = 0; iLoop < s.length; iLoop++) {
byte[] temp = getBytes(s[iLoop]);
System.out.println("1out->"+s[iLoop]);
for (int jLoop = 0; jLoop < bLength; jLoop++) {
buf[iLoop * bLength + jLoop] = temp[jLoop];
}
}
return buf;
}
/****************************************/
public long[] Bytes2Longs(byte[] buf) {
byte bLength = 8;
long[] s = new long[buf.length / bLength];
for (int iLoop = 0; iLoop < s.length; iLoop++) {
byte[] temp = new byte[bLength];
for (int jLoop = 0; jLoop < bLength; jLoop++) {
temp[jLoop] = buf[iLoop * bLength + jLoop];
}
s[iLoop] = getLong(temp);
}
return s;
}
public byte[] Longs2Bytes(long[] s) {
byte bLength = 8;
byte[] buf = new byte[s.length * bLength];
for (int iLoop = 0; iLoop < s.length; iLoop++) {
byte[] temp = getBytes(s[iLoop]);
for (int jLoop = 0; jLoop < bLength; jLoop++) {
buf[iLoop * bLength + jLoop] = temp[jLoop];
}
}
return buf;
}
}
